Field studies

Acoustic studies

Captivity studies

An Apparent Decrease in the Prevalence of "Ross Sea Killer Whales" in the Southern Ross Sea. Ainley, David G. et al. (2009).

Age determination and reproductive traits of killer whales entrapped in ice off Aidomari, Hokkaido, Japan. Amano, Masao, et al. (2008).

Satellite tracking reveals distinct movement patterns for Type B and Type C killer whales in the southern Ross Sea, Antarctica. Andrews, Russel D. et al. (2008).

Population structure of melon-headed whales (Peponocephala electra) in the Hawaiian Archipelago: Evidence of multiple populations based on photo identification. Aschettino, Jessica M. (2011).

Distinguishing the Impacts of Inadequate Prey and Vessel Traffic on an Endangered Killer Whale (Orcinus orca) Population. Ayers, Katherine L., et al. (2012).

A review of false killer whales in Hawaiian waters: biology, status, and risk factors. Baird, Robin W. (2009).

Killer whales in Hawaiian waters: information on population identity and feeding habits. Baird, Robin W., et al. (2006).

Occurrence and behaviour of transient killer whales: seasonal and pod-specific variability, foraging behaviour, and prey handling. Baird, R.W., Lawrence M. Dill. (1995).

Social organization of mammal-eating killer whales: group stability and dispersal patterns Baird, Robin W. and Hal Whitehead (2000).

Predation on gray whales and prolonged feeding on submerged carcasses by transient killer whales at Unimak Island, Alaska.Barrett-Lennard, Lance G. et al. (2011)

Dolphins and African apes: comparisons of sympatric socio-ecology. Bearzi, Maddalena, Craig B. Stanford (2007).

Evidence of Teaching In Atlantic Spotted Dolphins (Stenella frontalis) by Mother Dolphins Foraging in the Presence of their Calves. Bender, Courtney E., et al. (2008).

Resident and Transient-type Killer Whales, Orcinus orca, in Southeast Kamchatka, Russia. Burdin, Alexander M., et al.

Status of Killer Whales (Orcinus orca) in Eastern Kamchatka (Russian Far East) Based on Photo-Identification and Acoustic Studies. Preliminary Results. Burdin, Alexander M., (2007).

Dolphin social intelligence: complex alliance relationships in bottlenose dolphins and a consideration of selective environments for extreme brain size evolution in mammals. Connor, Richard (2007).

Persistent organic pollutants in chinook salmon (Oncorhynchus tshawytschea): implications for resident killer whales of British Columbia and adjacent waters. Cullon, Donna L., et al. (2009)

Ecological aspects of transient killer whales (Orcinus orca) as predators in southeastern Alaska Dalheim, Marilyn, Paula A. White (2010).

Eastern temperate North Pacific offshore killer whales (Orcinus orca): Occurrence, movements, and insights into feeding ecology Dalheim, Marilyn, et al. (2008).

Killer whale ecotypes: is there a global model? de Bruyn, et al. (2012).

Vocal behaviour and feeding ecology of killer whales Orcinus orca around Shetland, UK. Deecke, et al. (2011).

Incidence of ship strikes of large whales in Washington State. Douglas, et al. (2008).

Antarctic killer whales make rapid, round-trip movements to subtropical waters: evidence for physiological maintenance migrations? Durban, et al. (2011).

Photographic mark-recapture analysis of clustered mammal-eating killer whales around the Aleutian Islands and Gulf of Alaska. Durban, et al. (2010).

The structure of the discrete call repertoire of killer whales Orcinus orca from Southeast Kamchatka. Filatova O.A., et al. (2007).

Out of the Pacific and Back Again: Insights into the Matrilineal History of Pacific Killer Whale Ecotypes. Foote, Andrew, et al. (2011).

Ecological, morphological and genetic divergence of sympatric North Atlantic killer whale populations. Foote, Andrew, et al. (2009).

Mortality rate acceleration and post-reproductive lifespan in matrilineal whale species Foote, Andrew (2008).

Shark predation and tooth wear in a population of northeastern Pacific killer whales Ford, John K.B., et al. (2010).

Linking killer whale survival and prey abundance: food limitation in the oceans' apex predator? Ford, John K.B., et al. (2009).

Selective foraging by fish-eating killer whales Orcinus orca in British Columbia Ford, John K.B., Graeme M. Ellis (2006).

Prey selection and food sharing by fish-eating 'resident' killer whales (Orcinus orca) in British-Columbia Ford, John K.B., Graeme M. Ellis (2005).

Linking prey to population dynamics: did food limitation cause recent declines of 'resident' killer whales (Orcinis orca) in British Columbia? Ford, John K.B., et al (2005).

Dietary specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British Columbia and adjacent waters Ford, J.K.B., et al. (1999).

Inferred Paternity and Male Reproductive Success in a Killer Whale (Orcinus orca) Population Ford MJ, et al. (2011).

Adaptive Prolonged Postreproductive Life Span in Killer Whales Foster, Emma, et al. (2012).

Social network correlates of food availability in an endangered population of killer whales, Orcinus orca Foster, Emma, et al. (2012).

Do Orcas Use Symbols? Garrett, H. (2002).

Evaluating potential infectious disease threats for southern resident killer whales, Orcinus orca: a model for endangered species Gaydos, J., et al (2003).

First Mass Stranding of Killer Whales (Orcinus orca) in the Gulf of California, Mexico Guerrero-Ruiz, Mercedes, et al. (2006).

Vulnerability of a killer whale social network to disease outbreaks Guimaraes, P.R., et al. (2007).

Killer whale predation on bluefin tuna: exploring the hypothesis of the endurance-exhaustion technique Guinet, C., et al. (2007).

Species and stock identification of scale/tissue samples from southern resident killer whale predation events collected off the Washington coast during PODs 2009 cruise on the McArthur II Hanson, Bradley, et al. (2010).

Species and stock identification of prey consumed by endangered southern resident killer whales in their summer range Hanson, Bradley, et al. (2010).

Assessing age distributions of killer whale Orcinus orca populations from the composition of endogenous fatty acids in their outer blubber layers Herman, David P., et al. (2008).

Killer Whales (Orcinus orca) Face Protracted Health Risks Associated with Lifetime Exposure to PCBs Hickie, Brendan E., et al. (2007).

Evolution of population structure in a highly social top predator, the killer whale Hoelzel, A. Rus, et al. (2007).

Killer whale predation on marine mammals at Punta Norte, Argentina; food sharing, provisioning and foraging strategy Hoelzel, A. Rus (1991).

Low worldwide genetic diversity in the killer whale (Orcinus orca): implications for demographic history Hoelzel, A. Rus, et al. (2002).

The social organization of resident-type killer whales (Orcinus orca) in Avacha Gulf, Northwest Pacific, as revealed through association patterns and acoustic similarity Ivkovich, Tatiana, et al. (2009).

The evolution of menopause in cetaceans and humans: the role of demography Johnstone, Rufus A. and Michael A. Cant (2010).

Effects of age, sex and reproductive status on persistent organic pollutant concentrations in "Southern Resident" killer whales Krahn M, et al. (2009).

Persistent organic pollutants and stable isotopes in biopsy samples (2004/2006) from Southern Resident killer whales Krahn M, et al. (2007).

Cultural transmission of tool use in bottlenose dolphins Krützen M, et al. (2005).

Role of Peers in Cultural Innovation and Cultural Transmission: Evidence from the Play of Dolphin Calves Kuczaj, Stan A., et al. (2006).

Mitochondrial sequence divergence among Antarctic killer whale ecotypes is consistent with multiple species LeDuc, Richard G, et al. (2008).

Large brains and lengthened life history periods in odontocetes Lefebvre, L, et al. (2006).

Cetacean sleep: An unusual form of mammalian sleep Lyamina, Oleg I., et al (2008).

Towards a New Paradigm of Non-Captive Research on Cetacean Cognition Marino, Lori, Toni Frohoff (2011).

A claim in search of evidence: reply to Manger's thermogenesis hypothesis of cetacean brain structure Marino, Lori et al. (2008).

Cetaceans Have Complex Brains for Complex Cognition Marino, Lori et al. (2007).

Neuroanatomy of the killer whale (Orcinus orca) from magnetic resonance images Marino, Lori et al. (2004).

Anatomy and three-dimensional reconstructions of the brain of a bottlenose dolphin (Tursiops truncatus) from magnetic resonance images Marino, Lori et al. (2001).

Satellite-Monitored Radio Tracking as a Method for Studying Cetacean Movements and Behaviour Mate, B. (1989a).

Ongoing population-level impacts on killer whales Orcinus orca following the "Exxon Valdez" oil spill in Prince William Sound, Alaska Matkin, C, et al. (2008).

Eusociality, menopause and information in matrilineal whales McAuliffe, Katherine and Hal Whitehead. (2005).

Divergence date estimation and a comprehensive molecular tree of extant cetaceans McGowen, Michael R. (2009).

Site fidelity and association patterns of a rare species: pygmy killer whales (Feresa attenuata) in the main Hawaiian Islands McSweeney, et al. (2008).

Killer Whales and Herring: Using Sound to Get a Meal Miller, Lee A., et al. (2006).

Diversity in sound pressure levels and estimated active space of resident killer whale vocalizations Miller, P.J. (2006).

Complete mitochondrial genome phylogeographic analysis of killer whales (Orcinus orca) indicates multiple species Morin, Phillip A. et al. (2010).

Genetic analysis of killer whale (Orcinus Orca) historical bone and tooth samples to identify western U.S. ecotypes Morin, Phillip A. et al. (2006).

Cultural displacement and replacement in the songs of Australian humpback whales Noad, Michael J et al. (2000).

Close approaches by vessels elicit surface active behaviors by southern resident killer whales Noren, Dawn P., et al. (2009).

Multidisciplinary investigation of stranded harbor porpoises (Phocoena phocoena) in Washington State with an assessment of acoustic trauma as a contributory factor (2 May - 2 June 2003) Norman, S.A. et al. (2004).

The influence of social affiliation on individual vocal signatures of northern resident killer whales (Orcinus orca) Nousek, Anna E., et al. (2006).

Life History and Population Dynamics of Northern Resident Killer Whales (Orcinus orca) in British Columbia) Olesiuk, P.F., G.M. Ellis and J.K.B Ford (2005)

Life history and population dynamics of resident killer whales (Orcinus orca) in the coastal waters of British Columbia and Washington State Olesiuk, P.F., et al. (1990).

Observations of killer whales off East Antarctica, 82°-95°E, in 2009 Olson, Paula A, et al. (2012).

Culture Shock Pain, Stephanie (2001).

Geographic Patterns of Genetic Differentiation among Killer Whales in the Northern North Pacific Parsons, K.M., et al. (2013).

The social dynamics of southern resident killer whales and conservation implications for this endangered population Parsons, K.M., et al. (2009).

Social cohesion among kin, gene flow without dispersal and the evolution of population genetic structure in the killer whale (Orcinus orca) Pilot, M., et al. (2009).

Killer Whale - The top, top, predator edited by Pitman, R. (2011).

Cooperative hunting behavior, prey selectivity and prey handling by pack ice killer whales (Orcinus orca), type B, in Antarctic Peninsula waters Pitman, R., and John Durban. (2011).

Observations of a distinctive morphotype of killer whale (Orcinus orca), type D, from subantarctic waters Pitman, R., et al. (2010).

A dwarf form of killer whale in Antarctica Pitman, Robert, et al. (2007).

Good whale hunting: two tantalizing Russian reports take the author on a quest to the Antarctic, in search of two previously unrecognized kinds of killer whale Pitman, Robert (2003).

PBDEs, PBBs, and PCNs in Three Communities of Free-Ranging Killer Whales (Orcinus orca) from the Northeastern Pacific Ocean Rayne, Sierra, et al. (2004).

Can Genetic Differences Explain Vocal Dialect Variation in Sperm Whales, Physeter macrocephalus? Rendell, L., et al. (2011).

Culture in Whales and Dolphins Rendell, L., Hal Whitehead (2001).

Cultural traditions and the evolution of reproductive isolation: ecological speciation in killer whales? Riesch, R., et al (2012).

Anatomical evidence for a countercurrent heat exchanger associated with dolphin testes. Rommel, Sentiel A. et al. (1991).

High PCB concentrations in free-ranging Pacific killer whales, Orcinus orca: Effects of age, sex and dietary preference Ross, Peter S., et al. (2000).

Killer whales as sentinels of marine ecosystem contamination Ross, Peter S. (2002).

Climate change and a poleward shift in the distribution of the Pacific white-sided dolphin in the northeastern Pacific Salvadeo, Christian J., et al. (2010).

Killer whales (Orcinus orca) produce ultrasonic whistles. Samarra FI, et al. (2010).

Foraging strategies of sympatric killer whale (Orcinus orca) populations in Prince William Sound, Alaska Saulitis, Eva, et al. (2000).

Distribution of killer whale (Orcinus orca) pods in Prince William Sound, Alaska 1984-1996 Scheel, D., et al. (2001).

Polybrominated Diphenyl Ethers in Marine Ecosystems of the American Continents: Foresight from Current Knowledge Shaw, Susan D. and Kurunthachalam Kannan

Observations of Risso's dolphins Grampus griseus with gray whales, Eschrichtius robustus Shelden, K. et al. (1995).

The relationship between the acoustic behaviour and surface activity of killer whales (Orcinus orca) that feed on herring (Clupea harengus) Simon, M. et al. (2007).

Radiation of Extant Cetaceans Driven by Restructuring of the Oceans Steeman, Mette E et al. (2009).

Geographic variation in killer whale attacks on humpback whales in the North Pacific: implications for predation pressure Steiger, G.H., et al. (2008).

Long-term social structure of long-finned pilot whales (Globicephala melas) in the Strait of Gibraltar Stephanis, R. de, et al. (2008).

Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls Thewissen, J. G. M., et al. (2001).

Seasonality of reproduction in bottlenose dolphins, Tursiops truncatus Urian, K. W., et al. (1996).

First record of killer whales (Orcinus orca) feeding on Atlantic salmon (Salmo salar) in northern Norway suggest a multi-prey feeding type Vester, Heike and Kurt Hammerschmidt. (2012)

Insights on common dolphin (Delphinus delphis) social organization from genetic analysis of a mass-stranded pod Viricel, Amelia, et al. (2008)

The role of menopause and reproductive senescence in a long-lived social mammal Ward, E., et al. (2009).

Quantifying the effects of prey abundance on killer whale reproduction Ward, E., et al. (2009).

Culture and conservation of non-humans with reference to whales and dolphins: review and new directions Whitehead, H., et al. (2004).

Non-geographically based population structure of South Pacific sperm whales: dialects, fluke-markings and genetics Whitehead, H., et al. (1998).

Cultural Selection and Genetic Diversity in Matrilineal Whales Whitehead, H. (1998).

Competing Conservation Objectives for Predators and Prey: Estimating Killer Whale Prey Requirements for Chinook Salmon Williams, R., et al. (2011).

Behavioural responses of killer whales (Orcinus orca) to whale-watching boats: opportunistic observations and experimental approaches Williams, R. et al. (2002)

Parallel cultural and genetic lineages in Alaskan resident type killer whales Yurk, Harald. (2001).

Estimating abundance of killer whales in the nearshore waters of the Gulf of Alaska and Aleutian Islands using line-transect sampling Zerbini, A. N., et al. (2006).

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Ainley, David G., Grant Ballard, and Silvia Olmastroni. 2009. An Apparent Decrease in the Prevalence of "Ross Sea Killer Whales" in the Southern Ross Sea. Aquatic Mammals 2009, 35(3), 335-347.

ABSTRACT
Killer whales (Orcinus orca), both ecotype-B and -C, are important to the Ross Sea, Antarctic ecosystem. The ecotype-C is referred to as "Ross Sea [RS] killer whale." Herein, we review data on occurrence patterns and diet of RS killer whales and present new information on numbers observed in the southwestern Ross Sea, 2002-2003 to 2008-2009 austral summers. These "resident" whales appear to feed principally on fish, including the large Antarctic toothfish (Dissostichus mawsoni). On the basis of sea watches from Cape Crozier, Ross Island, sighting frequency and average group size appears to have decreased; prevalence as indicated by casual observations from helicopter pilots flying over the area on a daily basis has also decreased in nearby McMurdo Sound. Consistent with a decrease in the catch-per-unit-effort of scientific fishing for toothfish in McMurdo Sound, we suggest and review evidence that the change in RS killer whale numbers in the southern Ross Sea is related to an industrial fishery-driven, density-dependent northward contraction of the toothfish stock and not to changes in the physical (and, in turn, biological) environment. We surmise that in this closely coupled foodweb, composed of very abundant penguin, seal, and whale components, loss of the toothfish option for RS killer whales would force more direct competition with other predators for capture of the smaller-fish prey. Therefore, we propose, the RS killer whales have opted to move elsewhere, in a scenario consistent with that of the Pacific coast of Canada, where numbers of resident killer whales have decreased following the loss of large fish as a prey choice. Full paper HERE (870kb).

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Amano Masao, Tadasu K. Yamada, Robert L. Borwness, Jr., and Yoshikazu Uni. 2011. Age determination and reproductive traits of killer whales entrapped in ice off Aidomari, Hokkaido, Japan. Journal of Mammalogy, 92(2):275–282, 2011.

ABSTRACT

On 7 February 2005 a group of 9 killer whales (Orcinus orca) were trapped in drifting sea ice and died at Aidomari, Hokkaido, Japan. We carried out age determination based on tooth growth layers and examined the reproductive organs of these whales. Growth layer groups (GLGs) in the dentine and cementum were readable, even in the old specimens, and complementary to each other in decalcified and stained thin sections of lower teeth. Reliable age determination of killer whales is feasible, and GLGs are accumulated annually. The longitudinal growth of the teeth continued until about 20 years of age, which is much longer than for the corresponding age in other delphinids. Counts of corpora lutea and albicantia increased linearly with age from 3 to 7 in whales 13–34 years old, but the oldest female (59 years old) had only 8 corpora albicantia, which could indicate a decline in the ovulation rate in old females. Photographs of the original group trapped in the ice confirmed that at least 2 whales escaped or died and did not strand with the others. Therefore, this group was composed originally of a mature male, 1 possibly postreproductive female, 5 reproductively active females, 3 calves, and 2 or 3 unidentified individuals.

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Ayres, Katherine L., Rebecca K. Booth, Jennifer A. Hempelmann, Kari L. Koski, Candice K. Emmons, Robin W. Baird, Kelley Balcomb-Bartok, M. Bradley Hanson, Michael J. Ford, Samuel K. Wasser. 2012. Distinguishing the Impacts of Inadequate Prey and Vessel Traffic on an Endangered Killer Whale (Orcinus orca) Population. PLoS ONE 7(6): e36842. doi:10.1371/journal.pone.0036842.

ABSTRACT

Managing endangered species often involves evaluating the relative impacts of multiple anthropogenic and ecological pressures. This challenge is particularly formidable for cetaceans, which spend the majority of their time underwater. Noninvasive physiological approaches can be especially informative in this regard. We used a combination of fecal thyroid (T3) and glucocorticoid (GC) hormone measures to assess two threats influencing the endangered southern resident killer whales (SRKW; Orcinus orca) that frequent the inland waters of British Columbia, Canada and Washington, U.S.A. Glucocorticoids increase in response to nutritional and psychological stress, whereas thyroid hormone declines in response to nutritional stress but is unaffected by psychological stress. The inadequate prey hypothesis argues that the killer whales have become prey limited due to reductions of their dominant prey, Chinook salmon (Oncorhynchus tshawytscha). The vessel impact hypothesis argues that high numbers of vessels in close proximity to the whales cause disturbance via psychological stress and/or impaired foraging ability. The GC and T3 measures supported the inadequate prey hypothesis. In particular, GC concentrations were negatively correlated with short-term changes in prey availability. Whereas, T3 concentrations varied by date and year in a manner that corresponded with more long-term prey availability. Physiological correlations with prey overshadowed any impacts of vessels since GCs were lowest during the peak in vessel abundance, which also coincided with the peak in salmon availability. Our results suggest that identification and recovery of strategic salmon populations in the SRKW diet are important to effectively promote SRKW recovery.
Full paper HERE.

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Andrews, Russel D., Robert L. Pitman, Lisa T. Ballance. 2008. Satellite tracking reveals distinct movement patterns for Type B and Type C killer whales in the southern Ross Sea, Antarctica. Polar Biol (2008) 31:1461:1468.

ABSTRACT

During January/February 2006, we satellitetracked two different ecotypes of killer whales (Orcinus orca) in McMurdo Sound, Ross Sea, Antarctica, using surface-mounted tags attached with sub-dermal darts. A single Type B whale (pinniped prey specialist), tracked for 27 days, traveled an average net distance of 56.8 ± 32.8 km day, a maximum of 114 km day, and covered an estimated area of 49,351 km˛. It spent several days near two large emperor penguin (Aptenodytes forsteri) colonies, a potential prey item for this form. By contrast, four Type C killer whales (fish prey specialists) tracked for 7 - 65 days, traveled an average net distance of 20 ± 8.3 km day, a maximum of 56 net km day, and covered an estimated area of only 5,223 km˛. These movement patterns are consistent with those of killer whale ecotypes in the eastern North Pacific where mammal-eating "transients" travel widely and are less predictable in their movements, and fish-eating "residents" have a more localized distribution and more predictable occurrence, at least during the summer months.

INTRODUCTION

Long-term research on killer whales (Orcinus orca) in the Northeast Pacific and Antarctica has revealed that they can comprise populations of up to three sympatric, largely noninterbreeding ecotypes that specialize on different prey types (Ford et al. 1998; Baird 2000; Pitman and Ensor 2003). Furthermore, specific prey preferences among these ecotypes appear to be linked to different foraging habitats and movement patterns (Ford et al. 2000). In the eastern North Pacific, for example, the relationship between feeding and movement patterns has led to three ecotypes being referred to as "transients", a marine mammal-eating form; "residents", a fish-eating form that specializes on salmonids, and "offshores", a less well-known form that spends little time in coastal areas and whose food habits are largely unknown but do include fish (Bigg 1982; Ford et al. 2000; Baird 2000; Jones 2006). All three North Pacific killer whale ecotypes have overlapping geographic ranges (at least during summer), but residents occupy smaller ranges and are more predictably located than either transients or offshores. Recently, three different killer whale ecotypes were described from Antarctica based on field observations of color pattern differences, apparent prey specialization, habitat and herd size differences (Pitman and Ensor 2003), as well as differences in body length for at least two of the forms (Pitman et al. 2007). The three ecotypes were designated Types A, B and C, and it was suggested that they might represent different species. Type A, apparently the nominate form, lives in open water and preys mainly on Antarctic minke whales (Balaenoptera bonaerensis); Type B lives in loose pack ice where it preys mainly on seals (see also Visser et al. 2008), and Type C forages deep in the pack ice and among leads in the fast ice, and fish is its only known prey (see also Krahn et al. 2008).

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Aschettino, Jessica M., Robin W. Baird, Daniel J. McSweeney, Daniel L. Webster, Gregory S. Schorr, Jessica L. Huggins, Karen K. Martien, Sabre D. Mahaffy, Kristi L. West, 2011. Population structure of melon-headed whales (Peponocephala electra) in the Hawaiian Archipelago: Evidence of multiple populations based on photo identification. Marine Mammal Science doi: 10.1111/j.1748-7692.2011.00517.x.

ABSTRACT

Despite the presence of melon-headed whales in tropical and subtropical waters worldwide, little is known about this species. To assess population structure in Hawai'i, dedicated field efforts were undertaken from 2000 to 2009. Using only good quality photographs, there were 1,433 unique photo-identified individuals, of which 1,046 were distinctive. Of these, 31.5% were seen more than once. Resighting data combined with social network analyses showed evidence of two populations—a smaller, resident population, seen exclusively off the northwest region of the island of Hawai'i, and a larger population, seen throughout all the main Hawaiian Islands (hereafter the “main Hawaiian Islands” population). A Bayesian analysis examining the probability of movements of individuals between populations provided a posterior median dispersal rate of 0.0009/yr (95% CI = 0–0.0041), indicating the populations are likely demographically independent. Depth of encounters with the Hawai'i Island resident population was significantly shallower (median = 381 m) than those with the main Hawaiian Islands population (median = 1,662 m). Resightings of individuals have occurred up to 22 yr apart for the Hawai'i Island resident population and up to 13 yr apart for the main Hawaiian Islands population, suggesting long-term residency to the islands for both populations.

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Baird, R.W., 2009. A review of false killer whales in Hawaiian waters: biology, status, and risk factors. Report prepared for the U.S. Marine Mammal Commission under Order No. E40475499.

ABSTRACT

Recent management and conservation issues have arisen concerning false killer whales in Hawaiian waters. Two demographically isolated populations have been identified, a small (estimated 123 individuals) island-associated population around the main Hawaiian Islands (hereafter Hawai'i insular stock) and a larger (estimated 484 individuals) offshore population (hereafter Hawai'i pelagic stock). Individuals within the Hawai'i insular stock regularly move among islands and have been documented at distances of 110 km offshore. Less is known of movements/range of individuals from the Hawai'i pelagic stock; one group has been documented 42 km offshore and individuals likely move beyond the Hawaiian Exclusive Economic Zone. No information is available to assess trends in the Hawai'i pelagic stock. For the Hawai'i insular stock, a significant decline in sighting rates from aerial surveys conducted between 1993 and 2003 suggests a large decline in population size. Other available evidence also supports a decline in population size for the insular stock: a reduction in sighting rates from boat-based surveys since the mid-1980s, lower than expected survival based on photo-identification data, and much higher sighting rates and larger group sizes in a 1989 aerial survey compared to boat-based surveys since 2000. False killer whales in Hawai'i feed primarily on large game fish that are also the target of commercial and recreational fisheries. A number of potential conservation threats have been identified. Individuals from the Hawai'i insular stock have elevated levels of persistent organic pollutants. Three of nine individuals sampled had levels high enough to potentially influence health. Because of the overlap between false killer whale diet and commercially harvested fish, reduced prey size or abundance could influence false killer whale foraging success or nutritional levels. Significant declines in body size and/or catch per unit effort have been documented for several false killer whale prey species in Hawaiian waters. False killer whales have been documented taking fish off lines in both nearshore and offshore fisheries. Depredation of caught fish may lead to retaliatory shooting by fishermen although, given potential fines and penalties, such shooting is not likely to occur where it may be witnessed; thus there is no information available to assess the potential for this to influence population dynamics. With the overlap in diet with commercially and recreationally harvested fish, the potential for hook ingestion, either from depredation or from free-swimming hooked fish, is relatively high. Based on studies elsewhere, hook ingestion would have a high likelihood of leading to mortality. Bycatch may occur in nearshore kaka line or shortline fisheries that use similar, but shorter gear to offshore longline fisheries, but there is no observer coverage of nearshore fisheries. False killer whales are the most frequently recorded bycaught cetacean in the Hawai'i-based offshore longline fishery. Rates of serious injury and mortality have exceeded the potential biological removal (PBR) levels since bycatch rates and population levels were first available in 2000. Bycatch rates are underestimated as they do not take into account individuals that are not positively classified as to species or individuals that may break free with gear attached before being documented by observers. A number of research recommendations are presented to help reduce uncertainty and to clarify factors that may be influencing the population trajectories of both the Hawai'i insular and Hawai'i pelagic stocks, as well as to provide information that could be used to reduce bycatch rates or otherwise mitigate anthropogenic impacts on these populations.
A pdf copy can be downloaded from the Marine Mammal Commission web site or at Cascadia Research.

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Baird, R.W., D.J. McSweeney, C. Bane, J. Barlow, D.R. Salden, L.K. Antoine, R.G. LeDuc and D.L. Webster. 2006. Killer whales in Hawaiian waters: information on population identity and feeding habits. Pacific Science 60:523-530.

ABSTRACT

Killer whales (Orcinus orca) have only infrequently been reported from Hawaiian waters, and most of what is known about killer whales world-wide comes from studies in coastal temperate waters. Here we document 24 records of killer whales from within the Hawaiian Exclusive Economic Zone between 1994 and 2005. Killer whales were recorded 10 months of the year, most around the main Hawaiian Islands. While there were slightly more records than expected during the period when humpback whales are abundant around the islands, there is likely an increase in sighting effort during this period. Killer whales were documented feeding on both a humpback whale and cephalopods, and two species of small cetaceans were observed fleeing from killer whales. Although it is possible there are both marine mammal-eating and cephalopod-eating populations within Hawaiian waters, it seems more likely that Hawaiian killer whales may not exhibit foraging specializations as documented for coastal temperate populations, given the lower productivity and thus reduced selective pressure for specialization in tropical waters. Saddle patch pigmentation patterns were generally fainter and narrower than for those seen in killer whales from the temperate coastal North Pacific, though were most similar to the mammal-eating form of killer whale from those areas. Analysis of skin samples from two animals indicated two mitochondrial haplotypes, one identical to the "Gulf of Alaska transient 2" haplotype (a mammal-eating form), and the other a new haplotype one base different from haplotypes found for mammal-eating killer whales in coastal Alaskan waters. While more samples are needed, including samples from intervening areas, we suggest that killer whales around the Hawaiian Islands are likely isolated from populations in coastal temperate areas.
PDF copies are available

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Baird, Robin W. and Lawrence M. Dill (1995). Occurrence and behaviour of transient killer whales: seasonal and pod-specific variability, foraging behaviour, and prey handling. Can. J. Zool. 73(7): 1300-1311 (1995).

ABSTRACT

We studied the occurrence and behaviour of so-called transient killer whales (Orcinus orca) around southern Vancouver Island from 1986 to 1993. Occurrence and behaviour varied seasonally and among pods; some pods foraged almost entirely in open water and were recorded in the study area throughout the year, while others spent much of their time foraging around pinniped haulouts and other nearshore sites, and used the study area primarily during the harbour seal (Phoca vitulina) weaning-postweaning period. Overall use of the area was greatest during that period, and energy intake at that time was significantly greater than at other times of the year, probably because of the high encounter rates and ease of capture of harbour seal pups. Multipod groups of transients were frequently observed, as has been reported for "residents," but associations were biased towards those between pods that exhibited similar foraging tactics. Despite the occurrence of transients and residents within several kilometres of each other on nine occasions, mixed groups were never observed and transients appeared to avoid residents. Combined with previous studies on behavioural, ecological, and morphological differences, such avoidance behaviour supports the supposition that these populations are reproductively isolated.

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Baird, Robin W. and Hal Whitehead (2000). Social organization of mammal-eating killer whales: group stability and dispersal patterns. Canadian Journal of Zoology 78:2096-2105.

ABSTRACT

The social organization of mammal-eating "transient" killer whales (Orcinus orca) was studied off southern Vancouver Island from 1985 through 1996. Strong and long-term associations exist between individual transients, so sets of individuals with consistently high association levels, termed pods, can be delineated. Pods consist of individuals of mixed ages and sexes, and typically contain an adult female and one or two offspring (averaging 2.4 individuals). The mother-offspring bond remains strong into adulthood for some male (and less often for female) offspring. Other males disperse from their maternal pod and appear to become "roving" males, spending some of their time alone, and occasionally associating with groups that contain potentially reproductive females. These males appear to have no strong or long-term relationships with any individuals, and adult male - adult male associations occur significantly less often than expected by chance. Females that disperse from their natal pod appear to be gregarious (having high average association rates) but socially mobile (having low maximum association rates). Differences in social organization from the sympatric fish-eating "resident" killer whales (where no dispersal of either sex occurs) likely relate to differences in foraging ecology. Transient killer whales maximize per capita energy intake by foraging in groups of three individuals, whereas no such relationship has been documented for resident killer whales.

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Barrett-Lennard, Lance G., Craig O. Matkin, John W. Durban, 5, Eva L. Saulitis, David Ellifrit (2011). Predation on gray whales and prolonged feeding on submerged carcasses by transient killer whales at Unimak Island, Alaska. Mar Ecol Prog Ser, Vol. 421: 229–241.

ABSTRACT

As apex predators, killer whales Orcinus orca are expected to strongly influence the structure of marine communities by impacting the abundance, distribution, behavior, and evolution of their prey. Empirical assessments of these impacts are difficult, however, because killer whales are sparsely distributed, highly mobile, and difficult to observe. We present a 4 yr time series of observations of foraging and feeding behavior of >150 transient killer whales that aggregate annually during the northbound migration of gray whales past Unimak Island, Alaska. Most predatory attacks were on gray whale Eschrichtius robustus calves or yearlings and were quickly abandoned if calves were aggressively defended by their mothers. Attacks were conducted by groups of 3 to 4 killer whales, which attempted to drown their prey. Gray whales generally tried to move into shallow water along the shoreline when attacked; if they succeeded in reaching depths of 3 m or less, attacks were abandoned. Kills occurred in waters from 15 to 75 m deep or were moved into such areas after death. After some hours of feeding, the carcasses were usually left, but were re-visited and fed on by killer whales over several days. Carcasses or pieces of prey that floated onshore were actively consumed by brown bears Ursus arctos, and carcasses on the bottom were fed on by sleeper sharks Somniosus pacificus, apparently increasing the local density of both species.
FULL PAPER HERE.

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Bearzi, Maddalena, Craig B. Stanford (2007). Dolphins and African apes: comparisons of sympatric socio-ecology. Contributions to Zoology, 76 (4) 235-254.

ABSTRACT

Dolphins and African apes are distantly related mammalian taxa that exhibit striking convergences in their socioecology. In both cetaceans and African apes, two or more closely related species sometimes occur in sympatry. However, detailed reviews of the ways in which sympatric associations of dolphins and apes are similar have not been done. As fi eld studies of dolphins and apes have accumulated, comparisons of how the two groups avoid direct food competition when in sympatry have become possible. In this paper we review sympatric ecology among dolphins and African apes, and examine convergences in species-associations in each taxa. We review evidence for hypotheses that seek to explain avoidance of food competition, and consider whether ape-dolphin similarities in this area may be related to the way in which social groups in both taxa optimally exploit their food resources.
Free PDF copy or send requests to: mbearzi@earthlink.net

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Bender, Courtney E., Denise L. Herzing and David F. Bjorklund (2008). Evidence of Teaching In Atlantic Spotted Dolphins (Stenella frontalis) by Mother Dolphins Foraging in the Presence of their Calves. Animal Cognition [Epub ahead of print]. Published Online: July 29, 2008 DOI: 10.1007/s10071-008-0169-9

ABSTRACT

Teaching is a powerful form of social learning, but there is little systematic evidence that it occurs in species other than humans. Using long-term video archives the foraging behaviors by mother Atlantic spotted dolphins (Stenella frontalis) were observed when their calves were present and when their calves were not present, including in the presence of non-calf conspecifics. The nine mothers we observed chased prey significantly longer and made significantly more referential body-orienting movements in the direction of the prey during foraging events when their calves were present than when their calves were not present, regardless of whether they were foraging alone or with another non-calf dolphin. Although further research into the potential consequences for the naďve calves is still warranted, these data based on the maternal foraging behavior are suggestive of teaching as a social-learning mechanism in nonhuman animals. Electronic supplementary material The online version of this article (doi:10.1007/s10071-008-0169-9) contains supplementary material, which is available to authorized users.

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Burdin, Alexander M., Erich Hoyt, Hal Sato, Karina Tarasyan and Olga A. Filatova (?). Resident and Transient-type Killer Whales, Orcinus orca, in Southeast Kamchatka, Russia. SC/59/SM4.

ABSTRACT

Killer whales, Orcinus orca, were studied in Avacha Gulf, southeast Kamchatka, in the Russian Far East (RFE) from 1999-2003 using land- and boat-based photo-identification and sound recordings. A total of 121 photographically identified killer whales in the area have been determined to be residents based on (1) site fidelity with frequent re-sightings, (2) observations of predation on fish and (3) the recording of stable, resident-type dialects. The study has also documented transient-type marine mammal hunting killer whales in the RFE through morphological observations and biopsy documentation of contaminant levels and genetic characteristics. On 26 September 2003, some 32-37 resident-type killer whales were captured by the Utrish Dolphinarium Ltd, six of which had been photo-identified in previous years. One young female drowned in the nets; another young female was removed and sent to the Utrish Dolphinarium where she subsequently died. No more captures should be permitted until more is known about the population structure and population sizes of RFE killer whales.

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Burdin, Alexander M., Erich Hoyt, Olga A. Filatova, Tatyana Ivkovich, Karina Tarasyan and Hal Sato (2007). Status of Killer Whales (Orcinus orca) in Eastern Kamchatka (Russian Far East) Based on Photo-Identification and Acoustic Studies. Preliminary Results. SC/59/SM4.

ABSTRACT

From 1999-2006, a long-term study of killer whales (Orcinus orca) off eastern Kamchatka has conducted photoidentification and acoustic studies from a field station in Avacha Gulf. From 2002-2005, wide-area large ship surveys have expanded the study to other regions in the Russian Far East (RFE) including: northeast Kamchatka, Commander Islands, Chukotka, Kuril Islands and northeast Sakhalin. In this paper we mainly discuss the killer whale status on the eastern coast of Kamchatka, and give a brief review of available information regarding the killer whale status in other areas of the RFE. During the field seasons 2005-2006, a total of 434 individuals were identified in Avacha Gulf in at least three acoustic clans with different dialects. Most are resident-type fish-eating whales. Some transient-type marine mammal eating whales have also been recorded in Avacha Gulf and in other areas of the RFE. Transients as well as some residents show bites from the cookie cutter shark (Isistius brasiliensis) which may indicate long distance travel along the Asian coast or out to sea. To date, live captures have removed at least two subadult females from the Avacha Gulf residents. A live-capture quota of 6-10 killer whales in the RFE has been granted every year since 2002 (8 for 2007) although data remain inadequate to support this. The conflict between whales and fishermen in the Sea of Okhotsk due to killer whale depredation merits further study.

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Connor, Richard (2007). Dolphin social intelligence: complex alliance relationships in bottlenose dolphins and a consideration of selective environments for extreme brain size evolution in mammals. Phil. Trans. R. Soc. B doi:10.1098/rstb.2006.1997.

ABSTRACT

Bottlenose dolphins in Shark Bay, Australia, live in a large, unbounded society with a fission-fusion grouping pattern. Potential cognitive demands include the need to develop social strategies involving the recognition of a large number of individuals and their relationships with others. Patterns of alliance affiliation among males may be more complex than are currently known for any non-human, with individuals participating in 2-3 levels of shifting alliances. Males mediate alliance relationships with gentle contact behaviours such as petting, but synchrony also plays an important role in affiliative interactions. In general, selection for social intelligence in the context of shifting alliances will depend on the extent to which there are strategic options and risk. Extreme brain size evolution may have occurred more than once in the toothed whales, reaching peaks in the dolphin family and the sperm whale. All three 'peaks' of large brain size evolution in mammals (odontocetes, humans and elephants) shared a common selective environment: extreme mutual dependence based on external threats from predators or conspecific groups. In this context, social competition, and consequently selection for greater cognitive abilities and large brain size, was intense.

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Cullon, Donna L., Mark B. Yunker, Carl Alleyne, Neil J. Dangerfield, Sandra O'Neill, Michael J. Whiticar and Peter Ross (2009). Persistent organic pollutants in chinook salmon (Oncorhynchus tshawytschea): implications for resident killer whales of British Columbia and adjacent waters. Environmental Toxicology and Chemistry, Vol. 28, No. 1, pp. 148-161, 2009.

ABSTRACT

We measured persistent organic pollutant (POP) concentrations in chinook salmon (Oncorhynchus tshawytscha) in order to characterize dietary exposure in the highly contaminated, salmon-eating northeastern Pacific resident killer whales. We estimate that 97 to 99% of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dichlorodiphenyltrichloroethane (DDT), and hexachlorocyclohexane (HCH) in returning adult chinook were acquired during their time at sea. Highest POP concentrations (including PCBs, PCDDs, PCDFs, and DDT) and lowest lipids were observed in the more southerly chinook sampled. While feeding by salmon as they enter some more POP-contaminated near-shore environments inevitably contribute to their contamination, relationships observed between POP patterns and both lipid content and ∑13C also suggest a migration-related metabolism and loss of the less-chlorinated PCB congeners. This has implications for killer whales, with the more PCB-contaminated salmon stocks in the south partly explaining the 4.0 to 6.6 times higher estimated daily intake for ∑PCBs in southern resident killer whales compared to northern residents. We hypothesize that the lower lipid content of southerly chinook stocks may cause southern resident killer whales to increase their salmon consumption by as much as 50%, which would further increase their exposure to POPs.
Free PDF copy

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Dalheim, Marilyn, Paula A. White (2010). Ecological aspects of transient killer whales (Orcinus orca) as predators in southeastern Alaska. Wildlife Biology, Volume 6, No. 3: 308-322.

ABSTRACT

In this study we present empirical data on predator numbers, movements and area usage, and predation obtained from tracking transient killer whales (Orcinus orca) throughout the inland waters of southeastern Alaska, USA. During 1991-2007, we documented 155 transient killer whales via photo-identification methodology within this large study area (27,808 km2). Transient killer whales were distributed throughout southeastern Alaska and were present during all seasons, although not all individuals were seen each year. Resighting data suggested that within southeastern Alaska, maternal groups may partition area usage of their environment. By following whales for 1,467 km, we calculated a mean travel speed of 7.2 km/h with mean daily movements of 134 km ± 88 km/24 hours and ranging within 59-240 km/24 hours. Photographic matches demonstrated that most (86%) of the transient killer whales identified in southeastern Alaska also utilized British Columbia and Washington State waters. In contrast, photographic matches between whales in southeastern Alaska and whales seen off of California, USA, were rare, suggesting that different transient killer whale stocks occupy these two regions. Transient killer whales preyed upon Dall's porpoise (Phocoenoides dalli), Pacific white-sided dolphins (Lagenoryhncus obliquidens), harbor porpoise (Phocoena phocoena), minke whales (Balaenoptera acutorostrata), Steller sea lions (Eumetopias jubatus), harbor seals (Phoca vitulina), and seabirds. Potential prey species available, but not targeted, included humpback whales (Megaptera novaeangliae), elephant seals (Mirounga angustirostris), and sea otters (Enhydra lutris). Prey-handling techniques varied depending upon the prey being targeted with no evidence of prey specialization. During 114 encounters totaling 332.5 hours of direct observations of transient killer whales, we documented 36 predation events for a calculated kill rate of 0.62 prey items/24-hour period/whale. The data we present in this article provide a foundation of transient killer whale ecology aimed at improving our ability to understand the impact of transient killer whale predation on southeastern Alaska prey populations.
FULL PAPER HERE

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Dalheim, Marilyn, Alisa Schulman-Janiger, Nancy Black, Richard Tenullo, Dave Ellifrit, Kenneth C. Balcomb, III (2008). Eastern temperate North Pacific offshore killer whales (Orcinus orca): Occurrence, movements, and insights into feeding ecology MARINE MAMMAL SCIENCE, 24(3): 719-729 (July 2008).
No abstract. PDF of paper HERE (5.2 meg .pdf file.)

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de Bruyn, P. J. Nico, Cheryl A. Tosh1 and Aleks Terauds (2012). Killer whale ecotypes: is there a global model? Biol. Rev. (2012), pp. 000–000.

ABSTRACT

Killer whales, Orcinus orca, are top predators occupying key ecological roles in a variety of ecosystems and are one of the most widely distributed mammals on the planet. In consequence, there has been significant interest in understanding their basic biology and ecology. Long-term studies of Northern Hemisphere killer whales, particularly in the eastern North Pacific (ENP), have identified three ecologically distinct communities or ecotypes in that region. The success of these prominent ENP studies has led to similar efforts at clarifying the role of killer whale ecology in other regions, including Antarctica. In the Southern Hemisphere, killer whales present a range of behavioural, social and morphological characteristics to biologists, who often interpret this as evidence to categorize individuals or groups, and draw general ecological conclusions about these super-predators. Morphologically distinct forms (Type A, B, C, and D) occur in the Southern Ocean and studies of these different forms are often presented in conjunction with evidence for specialised ecology and behaviours. Here we review current knowledge of killer whale ecology and ecotyping globally and present a synthesis of existing knowledge. In particular, we highlight the complexity of killer whale ecology in the Southern Hemisphere and examine this in the context of comparatively well-studied Northern Hemisphere populations. We suggest that assigning erroneous or prefatory ecotypic status in the Southern Hemisphere could be detrimental to subsequent killer whale studies, because unsubstantiated characteristics may be assumed as a result of such classification. On this basis, we also recommend that ecotypic status classification for Southern Ocean killer whale morphotypes be reserved until more evidence-based ecological and taxonomic data are obtained.

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Deecke, Volker B., Milaja Nykänen, Andrew D. Foote, Vincent M. Janik (2011). Vocal behaviour and feeding ecology of killer whales Orcinus orca around Shetland, UK. Aquatic Biology 13:79-88.

ABSTRACT

Killer whales Orcinus orca are sighted regularly off Shetland, UK, but little is known about their numbers, diet and population identity. We aimed to relate vocal behaviour to diet of killer whales around Shetland in order to investigate population structure and differences in feeding strategies. Fieldwork was conducted in the summers of 2008 and 2009. We located killer whales through a sightings network and shore-based scans and collected photo-ID data, behavioural information, feeding data and acoustic recordings from a small boat. The majority of encounters (n = 14) were of small groups (1 to 15 individuals) travelling close to shore and feeding on marine mammals. Two encounters were with large groups (20+ individuals) feeding on herring Clupea harengus farther offshore. Seal-hunting groups vocalised rarely, producing pulsed calls, echolocation clicks and whistles almost exclusively when surface-active or milling after a kill. Herring-eating groups were largely silent during one encounter, but very vocal during the other. Analysis of pulsed calls identified 6 stereotyped call types for seal-hunting groups and 7 for herring-eating groups. No call types were shared between both kinds of groups. The vocal behaviour of seal-hunting groups showed striking parallels to that of Pacific marine mammal specialists and presumably evolved to decrease detection by acoustically sensitive prey. One call type produced by Shetland herring-eating killer whales matched a vocalisation that a previous study had described from Iceland and identified as a possible herding call that may function to concentrate herring during feeding. These findings point to behavioural and dietary specialisation among Shetland killer whales, which should be taken into account when making management decisions affecting these animals.

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Douglas, Annie B., John Calambokidis, Stephen Raverty, Steven J. Jeffries, Dyanna M. Lambourn and Stephanie A. Norman (2008). Incidence of ship strikes of large whales in Washington State. Journal of the Marine Biological Association of the United Kingdom, doi:10.1017/S0025315408000295.

ABSTRACT

Ship strikes of large whales cause mortalities worldwide, but there is uncertainty regarding the frequency and species involved. We examined 130 records (from 1980-2006) of large whale strandings in Washington State. Nineteen strandings (seven species) had evidence of ship-strikes. Fin whales (Balaenoptera physalus) had the highest incidence of ante-mortem ship strike (five of seven, with the remaining two possibly post-mortem) and all but one occurring since 2002. Six grey whales (Eschrichtius robustus) suffered 'possible ship strike' injuries, likely the result of their large numbers in the area, rather than high levels of ship strikes. Only one possible ship-struck humpback whale was recorded, despite concentrations of humpbacks feeding within shipping lanes in this region. This study shows dramatic differences in occurrences of ship-struck large whales by species, which we believe results from a combination of species' vulnerability to ship strikes, and how likely a struck whale is to be caught up on the bow of a ship and brought to waters where it can be examined.

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Durban, J. W., and R. L. Pitman. (2011). Antarctic killer whales make rapid, round-trip movements to subtropical waters: evidence for physiological maintenance migrations? Biological Letters doi: 10.1098/rsbl.2011.0875

ABSTRACT

Killer whales (Orcinus orca) are important predators in high latitudes, where their ecological impact is mediated through their movements. We used satellite telemetry to provide the first evidence of migration for killer whales, characterized by fast (more than 12 km/h, 6.5 knots) and direct movements away from Antarctic waters by six of 12 type B killer whales tagged when foraging near the Antarctic Peninsula, including all tags transmitting for more than three weeks. Tags on five of these whales revealed consistent movements to subtropical waters (30–37° S) off Uruguay and Brazil, in surface water temperatures ranging from -1.9°C to 24.2°C; one 109 day track documented a nonstop round trip of almost 9400 km (5075 nmi) in just 42 days. Although whales traveled slower in the warmest waters, there was no obvious interruption in swim speed or direction to indicate calving or prolonged feeding. Furthermore, these movements were aseasonal, initiating over 80 days between Februar y and April; one whale returned to within 40 km of the tagging site at the onset of the austral winter in June. We suggest that these movements may represent periodic maintenance migrations, with warmer waters allowing skin regeneration without the high cost of heat loss: a physiological constraint that may also affect other whales.
An open access PDF is available.

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Durban, J., D. Ellifrit, M. Dahlheim, J. Waite, C. Matkin, L. Barrett-Lennard, G. Ellis, R. Pitman, R. LeDuc and P. Wade (2010). Photographic mark-recapture analysis of clustered mammal-eating killer whales around the Aleutian Islands and Gulf of Alaska. Marine Biology Volume 157, Number 7, 1591-1604, DOI: 10.1007/s00227-010-1432-6

ABSTRACT

We used photographic mark-recapture methods to estimate the number of mammal-eating “transient” killer whales using the coastal waters from the central Gulf of Alaska to the central Aleutian Islands, around breeding rookeries of endangered Steller sea lions. We identified 154 individual killer whales from 6,489 photographs collected between July 2001 and August 2003. A Bayesian mixture model estimated seven distinct clusters (95% probability interval = 7–10) of individuals that were differentially covered by 14 boat-based surveys exhibiting varying degrees of association in space and time. Markov Chain Monte Carlo methods were used to sample identification probabilities across the distribution of clusters to estimate a total of 345 identified and undetected whales (95% probability interval = 255–487). Estimates of covariance between surveys, in terms of their coverage of these clusters, indicated spatial population structure and seasonal movements from these near-shore waters, suggesting spatial and temporal variation in the predation pressure on coastal marine mammals.

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Filatova O.A., Fedutin I.D., Burdin A.M., Hoyt E. (2007). The structure of the discrete call repertoire of killer whales Orcinus orca from Southeast Kamchatka. Bioacoustics V 16(3): 261-280.

ABSTRACT

The problem of categorization arises in any classification system because classes should be discrete while the characteristics of most natural objects and aspects of nature are more or less gradual. In systematics, this problem usually is solved by creating several levels of categories, such as class, order, family, genus and species.
In the existing killer whale discrete call classification, only two levels occur - call type and call subtype. In this paper we describe structural categories at a broader level than call type in the discrete sounds of killer whales and compare these categories between and within vocal clans in a community of resident killer whales from Southeast Kamchatka, Russian Far East, and also with killer whales outside this community. We found four main classes of discrete calls in the repertoire of resident killer whales from Southeast Kamchatka. The calls of Southeast Kamchatka transient killer whales and Sakhalin killer whales do not fall into these classes. This suggests that the resident killer whale community from Southeast Kamchatka has some rules defining the structure of calls which are typical for this community. Consequently, all resident killer whales from Southeast Kamchatka can be said to share the same vocal tradition.
A pdf copy is available upon request from alazor@rambler.ru

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Foote, Andrew D., Phillip A. Morin, John W. Durban, Eske Willerslev, Ludovic Orlando, M. Thomas P. Gilbert; (2011). Out of the Pacific and Back Again: Insights into the Matrilineal History of Pacific Killer Whale Ecotypes. PLoS ONE 6(9): e24980. doi:10.1371/journal.pone.0024980.

ABSTRACT

Killer whales (Orcinus orca) are the most widely distributed marine mammals and have radiated to occupy a range of ecological niches. Disparate sympatric types are found in the North Atlantic, Antarctic and North Pacific oceans, however, little is known about the underlying mechanisms driving divergence. Previous phylogeographic analysis using complete mitogenomes yielded a bifurcating tree of clades corresponding to described ecotypes. However, there was low support at two nodes at which two Pacific and two Atlantic clades diverged. Here we apply further phylogenetic and coalescent analyses to partitioned mitochondrial genome sequences to better resolve the pattern of past radiations in this species. Our phylogenetic reconstructions indicate that in the North Pacific, sympatry between the maternal lineages that make up each ecotype arises from secondary contact. Both the phylogenetic reconstructions and a clinal decrease in diversity suggest a North Pacific to North Atlantic founding event, and the later return of killer whales to the North Pacific. Therefore, ecological divergence could have occurred during the allopatric phase through drift or selection and/or may have either commenced or have been consolidated upon secondary contact due to resource competition. The estimated timing of bidirectional migration between the North Pacific and North Atlantic coincided with the previous inter-glacial when the leakage of fauna from the Indo-Pacific into the Atlantic via the Agulhas current was particularly vigorous. Full paper HERE.

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Foote, Andrew D., Jason Newton, Stuart B. Pierteney, Eske Willerslev and M. Thomas P. Gilbert; (2009). Ecological, morphological and genetic divergence of sympatric North Atlantic killer whale populations. Molecular Ecology (2009) 18, 5207-5217

ABSTRACT

Ecological divergence has a central role in speciation and is therefore an important source of biodiversity. Studying the micro-evolutionary processes of ecological diversification at its early stages provides an opportunity for investigating the causative mechanisms and ecological conditions promoting divergence. Here we use morphological traits, nitrogen stable isotope ratios and tooth wear to characterize two disparate types of North Atlantic killer whale. We find a highly specialist type, which reaches up to 8.5 m in length and a generalist type which reaches up to 6.6 m in length. There is a single fixed genetic difference in the mtDNA control region between these types, indicating integrity of groupings and a shallow divergence. Phylogenetic analysis indicates this divergence is independent of similar ecological divergences in the Pacific and Antarctic. Niche-width in the generalist type is more strongly influenced by between-individual variation rather than within-individual variation in the composition of the diet. This first step to divergent specialization on different ecological resources provides a rare example of the ecological conditions at the early stages of adaptive radiation.
Full paper available HERE.

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Foote, Andrew (2008). Mortality rate acceleration and post-reproductive lifespan in matrilineal whale species. Biol. Lett. 4, 189-191

ABSTRACT

The strength of selection to increase the span of a life stage is dependent upon individuals at that stage being able to contribute towards individual fitness and the probability of their surviving to that stage. Complete reproductive cessation and a long post-reproductive female lifespan as found in humans are also found in killer whale (Orcinus orca) and short-finned pilot whale (Globicephala macrorhynchus), but not in the long-finned pilot whale (Globicephala melaena). Each species forms kin-based, stable matrilineal groups and exhibits kin-directed behaviours that could increase inclusive fitness. Here, the initial mortality rate and mortality rate-doubling time of females of these three closely related whale species are compared. The initial mortality rate shows little variation among pilot whale species; however mortality rate accelerates almost twice as fast in the long-finned pilot whale as it does in killer whale and short-finned pilot whale. Selection for a long post-reproductive female lifespan in matrilineal whales may therefore be determined by the proportion of females surviving past the point of reproductive cessation.

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John K. B., Graeme M. Ellis, Craig O. Matkin, Michael H. Wetklo, Lance G. Barrett-Lennard, Ruth E. Withler (2011). Shark predation and tooth wear in a population of northeastern Pacific killer whales Aquatic Biology 11:213-224.

ABSTRACT

The cosmopolitan killer whale Orcinus orca feeds on a wide variety of prey types over its global range, but in at least some regions, genetically distinct and ecologically specialised lineages of killer whales coexist sympatrically. In coastal waters of the northeastern Pacific, 2 such lineages have been well described: the so-called ‘residents’ prey on teleost fish, especially salmonids and the other (‘transients’) on marine mammals. A third lineage in this region (‘offshores’) appears from chemical tracers to be ecologically distinct from residents and transients, but its diet is very poorly known. Here we describe 2 encounters with offshore killer whales during which multiple predation events involving sharks were observed. Using DNA analysis of tissue samples collected from these predation events, we identified the prey species as Pacific sleeper shark Somniosus pacificus and determined that a minimum of 16 individuals were consumed over the 2 encounters. This represents the first confirmed prey species of offshore killer whales based on field observations of foraging and the first record of any Somniosus species in the prey of Orcinus. We also show quantitatively that apical tooth wear is far greater in offshores than in resident and transient killer whales, and propose that such wear is at least in part due to abrasion from dermal denticles embedded in shark skin. Further studies are needed to determine whether offshore killer whales are as specialised ecologically as resident and transient killer whales, and whether sharks play a dominant role in their diet.

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Ford, John K.B., Graeme M. Ellis, Peter F. Olesiuk and Kenneth C. Balcomb (2009). Linking killer whale survival and prey abundance: food limitation in the oceans' apex predator? Biology Letters 2009.

ABSTRACT

Killer whales (Orcinus orca) are large predators that occupy the top trophic position in the world's oceans and as such may have important roles in marine ecosystem dynamics. Although the possible top-down effects of killer whale predation on populations of their prey have received much recent attention, little is known of how the abundance of these predators may be limited by bottom-up processes. Here we show, using 25 years of demographic data from two populations of fish-eating killer whales in the northeastern Pacific Ocean, that population trends are driven largely by changes in survival, and that survival rates are strongly correlated with the availability of their principal prey species, Chinook salmon (Oncorhynchus tshawytscha). Our results suggest that, although these killer whales may consume a variety of fish species, they are highly specialized and dependent on this single salmonid species to an extent that it is a limiting factor in their population dynamics. Other ecologically specialized killer whale populations may be similarly constrained to a narrow range of prey species by culturally inherited foraging strategies, and thus are limited in their ability to adapt rapidly to changing prey availability.

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Ford, John K.B., Graeme M. Ellis (2005). Selective foraging by fish-eating killer whales Orcinus orca in British Columbia. MARINE ECOLOGY PROGRESS SERIES Vol. 316: 185-199, 2006.

ABSTRACT

As the apex non-human marine predator, the killer whale Orcinus orca feeds on a wide diversity of marine fauna. Different ecotypic forms of the species, which often exist in sympatry, may have distinct foraging specialisations. One form found in coastal waters of the temperate NE Pacific Ocean, known as the 'resident' ecotype, feeds predominantly on salmonid prey. An earlier study that used opportunistic collection of prey remains from kill sites as an indicator of predation rates suggested that resident killer whales may forage selectively for chinook salmon Oncorhynchus tshawytscha, the largest but one of the least abundant Pacific salmon species. Potential biases in the prey fragment sampling technique, however, made the validity of this finding uncertain. We under-took field studies of foraging behaviour of resident killer whales to resolve this uncertainty and to examine potential variation in prey selection by season, geographical area, group membership and prey availability. Foraging by resident killer whales was found to frequently involve sharing by 2 or more whales. Prey fragments left at kill sites resulted mostly from handling and breaking up of prey for sharing, and all species and sizes of salmonids were shared. Resident killer whale groups in all parts of the study area foraged selectively for chinook salmon, probably because of the species' large size, high lipid content, and year-round availability in the whales' range. Chum salmon Oncorhynchus keta, the second largest salmonid, were also taken when available, but smaller sock-eye O. nerka and pink O. gorbuscha salmon were not significant prey despite far greater seasonal abundance. Strong selectivity for chinook salmon by resident killer whales probably has a significant influence on foraging tactics and seasonal movements, and also may have important implications for the conservation and management of both predator and prey.

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Ford, John K.B., Graeme M. Ellis (2005). Prey selection and food sharing by fish-eating 'resident' killer whales (Orcinus orca) in British-Columbia. Canadian Science Advisory Secretariat Research Document - 2005/041.

ABSTRACT

Three distinct, socially-isolated forms, or ecotypes, of killer whales (Orcinus orca), inhabit coastal waters of British-Columbia, Washington State, and southeastern Alaska. The so-called transient ecotype feeds primarily on marine mammal prey, the resident ecotype feeds primarily on fish, and the diet of the offshore ecotype is not known. A previous study of the diet of the resident and transient ecotypes using opportunistic collection of prey remains from kill sites as a primary measure of prey selection found that resident killer whales feed predominantly on salmonids, particularly on chinook salmon (Oncorhynchus tshawytscha). To address uncertainties concerning potential biases in the prey fragment sampling technique and questions regarding seasonal and geographic variability in diet, we conducted field studies of foraging behaviour during 1997-2004. Foraging by resident killer whales often involves cooperation among kin-related group members, and prey items are frequently shared by two or more whales. Adult males share prey less often than do females and subadults. Prey sharing does not appear to be related to prey size. Prey fragments left at kill sites result mostly from prey handling and sharing, and are reliable indicators of selection for different salmonid species by resident killer whales. Chinook is the predominant prey species taken by both northern and southern resident communities during May-August, but chum salmon (O. keta) is more prevalent in September-October, at least in northern residents. Coho salmon (O. kisutch) are taken in low numbers in June-October, but sockeye (O. nerka) and pink (O. gorbuscha) salmon are not significant prey species despite their high seasonal abundance. Non-salmonid fishes do not appear to represent an important component of resident whale diet during May-October. Their strong preference for chinook salmon may influence the year-round distribution patterns of resident killer whales in coastal British-Columbia and adjacent waters. Full paper here.

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Ford, J.K.B., Graeme. M. Ellis, Peter Olesiuk (2005). Linking prey to population dynamics: did food limitation cause recent declines of 'resident' killer whales (Orcinus orca) in British Columbia? Fisheries and Oceans Canada Research Document 2005/042 (www.dfo-mpo.gc.ca/csas). Not to be cited without permission of the authors.

ABSTRACT

Two populations of fish-eating killer whales (Orcinus orca) in British Columbia, known as residents, are listed under the Canadian Species-at-Risk Act due to thier small population size and recent unexplained declines in abundance. Threats considered to potentially affect survival and recovery of these populations include environmental pollutants, physical and acoustic disturbance, and reductions in the availability or quality of salmonids, their primary prey. Recent studies have shown that chinook salmon and, to a lesser degree, chum salmon, are important prey for resident killer whales, but other smaller salmonid species are not. In this report, we assess whether food limitation was potentially a significant factor in recent declines of these whale populations. We examined the relationship between trends in killer whale population dynamics based on long-term photo-identification data, and abundance levels of chinook and chum salmon off the British Columbia coast over the the past 25 years. Resident killer whale population productivity is regulated primarily by changes in survival. Periods of decline were primarily due to unusually high mortality rates that were experienced by all age- and sex-classes of whales and were synchronous in the socially-isolated two resident communities. Fluctuations in observed versus expected mortality rates showed a strong correlation with changes in chinook salmon abundance, but no relationship to chum salmon abundance. A sharp drop in coast-wide chinook abundance during the late 1990s was closely associated with a significant decline in resident whale surivial. The whales' preference for chinook salmon is likely due to the species' relatively large size, high lipid content and, unlike other salmonids, its year-round presence in the whales' range. Resident killer whales may be especially dependent on chinook during winter, when this species is the primary salmonid available in coastal waters, and the whales may be subject to nutritional stress leading to increased mortality if the quantity and/or quality of this prey resource declines. Chinook salmon is clearly of great importance to resident killer whales, but determining whether the species is the principal factor limiting whale productivity will require on-going monitoring of both salmon and whale population trends.

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Ford, J.K.B., G.M. Ellis, L.G. Barrett-Lennard, A.B. Morton, R.S. Palm, and K.C. Balcomb III (1999). Dietary specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British Columbia and adjacent waters. Canadian Journal of Zoology, Vol. 76, p. 1456-1471

ABSTRACT

Two forms of killer whale (Orcinus orca), resident and transient, occur sympatrically in coastal waters of British Columbia, Washington State, and southeastern Alaska. The two forms do not mix, and differ in seasonal distribution, social structure, and behaviour. These distinctions have been attributed to apparent differences in diet, although no comprehensive comparative analysis of the diets of the two forms has been undertaken. Here we present such an analysis, based on field observations of predation and on the stomach contents of stranded killer whales collected over a 20-year period. In total, 22 species of fish and 1 species of squid were documented in the diet of resident-type killer whales; 12 of these are previously unrecorded as prey of O. orca. Despite the diversity of fish species taken, resident whales have a clear preference for salmon prey. In field observations of feeding, 96% of fish taken were salmonids. Six species of salmonids were identified from prey fragments, with chinook salmon (Oncorhynchus tshawytscha) being the most common. The stomach contents of stranded residents also indicated a preference for chinook salmon. On rare occasions, resident whales were seen to harass marine mammals, but no kills were confirmed and no mammalian remains were found in the stomachs of stranded residents.
Transient killer whales were observed to prey only on pinnipeds, cetaceans, and seabirds. Six mammal species were taken, with over half of observed attacks involving harbour seals (Phoca vitulina). Seabirds do not appear to represent a significant prey resource. This study thus reveals the existence of strikingly divergent prey preferences of resident and transient killer whales, which are reflected in distinctive foraging strategies and related sociobiological traits of these sympatric populations.

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Foster, Emma A., Daniel W. Franks, Sonia Mazzi, Safi K. Darden, Ken C. Balcomb, John K. B. Ford, Darren P. Croft. Adaptive Prolonged Postreproductive Life Span in Killer Whales. Science Vol. 337 14 September 2012.

ABSTRACT
Prolonged life after reproduction is difficult to explain evolutionarily unless it arises as a physiological side effect of increased longevity or it benefits related individuals (i.e., increases inclusive fitness). There is little evidence that postreproductive life spans are adaptive in nonhuman animals. By using multigenerational records for two killer whale (Orcinus orca) populations in which females can live for decades after their final parturition, we show that postreproductive mothers increase the survival of offspring, particularly their older male offspring. This finding may explain why female killer whales have evolved the longest postreproductive life span of all nonhuman animals. Full paper HERE.

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Ford MJ, Hanson MB, Hempelmann JA, Ayres KL, Emmons CK, Schorr GS, Baird RW, Balcomb KC, Wasser SK, Parsons KM, Balcomb-Bartok K. Inferred Paternity and Male Reproductive Success in a Killer Whale (Orcinus orca) Population. The Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, Seattle, WA 98112.

ABSTRACT
We used data from 78 individuals at 26 microsatellite loci to infer parental and sibling relationships within a community of fish-eating ("resident") eastern North Pacific killer whales (Orcinus orca). Paternity analysis involving 15 mother/calf pairs and 8 potential fathers and whole-pedigree analysis of the entire sample produced consistent results. The variance in male reproductive success was greater than expected by chance and similar to that of other aquatic mammals. Although the number of confirmed paternities was small, reproductive success appeared to increase with male age and size. We found no evidence that males from outside this small population sired any of the sampled individuals. In contrast to previous results in a different population, many offspring were the result of matings within the same "pod" (long-term social group). Despite this pattern of breeding within social groups, we found no evidence of offspring produced by matings between close relatives, and the average internal relatedness of individuals was significantly less than expected if mating were random. The population's estimated effective size was <30 or about 1/3 of the current census size. Patterns of allele frequency variation were consistent with a population bottleneck. Full paper HERE.

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Foster, Emma A., Daniel W. Franks, Lesley J. Morrell, Ken C. Balcomb, Kim M. Parsons, Astrid van Ginneken, Darren P. Croft Social network correlates of food availability in an endangered population of killer whales, Orcinus orca. Animal Behaviour 83 (2012) 731e736.

ABSTRACT
For the majority of social species, group composition is dynamic, and individuals are interconnected in a heterogeneous social network. Social network structure has far-reaching implications for the ecology of individuals and populations. However, we have little understanding of how ecological variables shape this structure. We used a long-term data set (1984e2007) to examine the relationship between food availability and social network structure in the endangered southern resident killer whales. During the summer months individuals in this population feed primarily on chinook salmon, Oncorhynchus tshawytscha, which show annual variation in abundance. We tested the hypothesis that temporal variation in chinook salmon will correlate with variation in social network structure. Using a null model that controlled for population demography, group size and sampling effort, we found a significant relationship between the connectivity of the social network and salmon abundance, with a more interconnected social network in years of high salmon abundance. Our results demonstrate that resource availability may be an important determinant of social network structure. Given the central importance of the social network for population processes such as the maintenance of cooperation and the transmission of information and disease, a change in social network structure caused by a change in food availability may have significant ecological and evolutionary consequences. Full paper HERE.

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Garrett, H. (2002) Do Orcas Use Symbols?

ABSTRACT

Recent theoretical studies of culture in whales and dolphins have reviewed experimental research on captive animals and patterns of behavioral variation found in wild populations. Captive studies of cognitive processes in dolphins, such as imitation, teaching, and use of gestures and other symbolic representations, have provided indications of the capacity for culture in dolphins. The ethnographic approach, based on evolutionary ecology, has found evidence that the vocal and behavioral traditions of killer whales (Orcinus orca) appear to have no parallel outside humans. To date, however, no published theory has provided a synthesis that accommodates both the experimental findings and the ethnographic evidence. The theory of symbolic interactionism, borrowed and adapted from sociology, provides a conceptual framework for integrating the experimental "process-oriented" and the ethnographic "product-oriented" perspectives. Symbolic interactionism may help account for the divergent and complex cultural traditions found in sympatric orca populations. Full paper. Poster presentation (10.5 mg .pdf).

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Gaydos, Joseph K., Kenneth C. Balcomb, III, Richard W. Osborne and Leslie Dierauf. 2004. Evaluating potential infectious disease threats for southern resident killer whales, Orcinus orca: a model for endangered species . Biological Conservation Volume 117, Issue 3, Pages 253-262.

ABSTRACT

Infectious diseases have the potential to play a role in the decline of threatened wildlife populations, as well as negatively affect their long-term viability, but determining which infectious agents present risks can be difficult. The southern resident killer whale, Orcinus orca, population is endangered and little is known about infectious diseases in this species. Using available reference literature, we identified 15 infectious agents (bacteria, viruses, and fungi) reported in free-ranging and captive killer whales, as well as 28 additional infectious agents reported in free-ranging and captive odontocete species sympatric to southern resident killer whales. Infectious agents were scored as having a high, medium, or low ability to affect fecundity or reproductive success, to cause disease in individual animals, and to cause epizootics. Marine Brucella spp., cetacean poxvirus, cetacean morbilliviruses, and herpesviruses were identified as high priority pathogens that warrant further study. Using identified pathogens to develop a standardized necropsy and disease testing protocol for southern resident killer whales and sympatric odontocetes will improve future efforts to better understand the impacts of priority and non-priority infectious agents on southern resident killer whales. This model can be used to evaluate potential infectious disease risks in other threatened wildlife populations.

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Guerrero-Ruiz, Mercedes; Pérez-Cortés M., Héctor; Salinas Z., Mario; Urbán R., Jorge 2006. First Mass Stranding of Killer Whales (Orcinus orca) in the Gulf of California, Mexico Aquatic Mammals, Volume 32, Number 3, September 2006 , pp. 265-272

ABSTRACT

We present the first report of a mass stranding of killer whales (Orcinus orca) in Mexican waters. This species is a temporal inhabitant of the region. On 31 July 2000, eight killer whales stranded alive at the southern tip of Isla San José in Bahía de La Paz (24° 54′ N, 110° 35′ W). All the individuals died despite the attempts performed by local fishermen to return them to sea. The group consisted of an undetermined number of females, immature males, and two calves. Skin and blubber samples were collected, as well as a skull on 2 August from a 4.6-m immature male. A second skull was collected on 19 August, which belonged to an individual of undetermined sex that measured 5 m in length. The teeth from both individuals were completely worn down. A couple of months later, two other skulls were collected. Individual strandings of killer whales are rare, and six records have been documented in the Mexican Pacific and Gulf of California. This report represents the first mass stranding of killer whales in Mexico. Since 1972, more than 160 killer whale sightings have been collected in the Gulf of California, with more than 90 photo-identified killer whales; nevertheless, no matches with the stranded individuals were found. There are few cases of killer whales found stranded live, probably as a result of whales chasing or following prey, or as a result of an outgoing tide. Causes of this stranding remain unknown.

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Guimaraes, P.R. Jr., M.A. de Menezes, R.W. Baird, D. Lusseau, P. Guimaraes, and S.F. dos Reis. 2007. Vulnerability of a killer whale social network to disease outbreaks. Physical Review E 76, 042901.

ABSTRACT

Emerging infectious diseases are among the main threats to conservation of biological diversity. A cruicial task facing epidemiologists is to predict the vulnerability of populations of endangered animals to disease outbreaks. In this context, the network structure of social interactions within animal populations may affect disease spreading. However, endangered animal populations are often small and to investigate the dynamics of small networks is a difficult task. Using network theory, we show that the social structure of an endangered population of mammal-eating killer whales is vulnerable to disease outbreaks. This feature was found to be a consequence of the combined effects of the toplogy and strength of social links among individuals. Our results uncover a serious challenge for conservation of the species and its ecosystem. In addition, this study shows that the network approach can be useful to study dynamical processes in very small networks.

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C. Guinet, P. Domenici, R. de Stephanis, L. Barrett-Lennard, J. K. B. Ford, P. Verborgh (2007). Killer whale predation on bluefin tuna: exploring the hypothesis of the endurance-exhaustion technique Mar Ecol Prog Ser 347: 111–119.

ABSTRACT

Killer whales Orcinus orca occur in the area of the Strait of Gibraltar, where they prey on migrating bluefin tuna Thunnus thynnus. In the spring, killer whales were observed to chase tuna for up to 30 min at a relatively high sustained speed (3.7 ± 0.2 m s-1) until they captured them. Using simple models based on previous locomotor performance data on killer whales and thunnids, we investigated the hypothesis that killer whales push tuna beyond their aerobic limits to exhaust and capture them. To test this hypothesis, the endurance of bluefin tuna was estimated from data on maximum burst and aerobic swimming available for bluefin and yellowfin tuna T. albacares. The endurance performance of killer whales was evaluated on the basis of the maximal rate of oxygen uptake during exercise (VO2max). We modelled the maximum aerobic power output for a killer whale according to swimming speed using a VO2max ranging between 20 and 30 ml O2 kg-1) min-1). The output of this model was compared to the observed sustained swimming speed of killer whales chasing prey over long durations. Our results support the hypothesis that killer whales may use an endurance-exhaustion technique to catch small to medium sized (up to 0.8 to 1.5 m) bluefin tuna, while larger tuna may be inaccessible to killer whales unless they use cooperative hunting techniques or benefit through depredation of fish caught on long lines, drop lines or trap nets. Full paper HERE.

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M. Bradley Hanson, Jennifer Hempelmann-Halos, Donald M. Van Doornik (2010). Species and stock identification of scale/tissue samples from southern resident killer whale predation events collected off the Washington coast during PODs 2009 cruise on the McArthur II NOAA Doc # BB0149

INTRODUCTION

In order to improve the Critical Habitat designation for SRKW and determine prey selection during the winter and spring, the NWFSC has undertaken 5 survey cruises on the McArthur II in the coastal waters of Washington Oregon and British Columbia between 2004 and 2009 to locate pods from this population.
Quote: "...on 26 March 2010 near Gray's Canyon, L pod was sighted traveling northeast just offshore of Ocean Shores, Washington...Two predation event samples were collected as the whales travel parallel to the coast between the entrances to Gray's Harbor and Willapa Bay...both of the samples were Chinook salmon, and the most likely regions of origin for these samples were in the Columbia River; one from the Upper Columbia, the other from the Snake River."
FULL PAPER HERE

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M. Bradley Hanson, Robin W. Baird, John K. B. Ford, Jennifer Hempelmann-Halos, Donald M. Van Doornik, John R. Candy, Candice K. Emmons, Gregory S. Schorr, Brian Gisborne, Katherine L. Ayres, Samuel K. Wasser, Kenneth C. Balcomb, Kelley Balcomb-Bartok, John G. Sneva, Michael J. Ford (2010). Species and stock identification of prey consumed by endangered southern resident killer whales in their summer range Endang Species Res Vol. 11: 69-82, 2010

ABSTRACT

Recovery plans for endangered southern resident killer whales Orcinus orca have identified reduced prey availability as a risk to the population. In order to better assess this risk, we studied prey selection from 2004 to 2008 in 2 regions of the whales' summer range: San Juan Islands, Washington and the western Strait of Juan de Fuca, British Columbia. Following the whales in a small boat, we collected fish scales and tissue remains from predation events, and feces, using a fine mesh net. Visual fish scale analysis and molecular genetic methods were used to identify the species consumed. Chinook salmon, a relatively rare species, was by far the most frequent prey item, confirming previous studies. For Chinook salmon prey, we used genetic identification methods to estimate the spawning region of origin. Of the Chinook salmon sampled, 80 to 90% were inferred to have originated from the Fraser River, and only 6 to 14% were inferred to have originated from Puget Sound area rivers. Within the Fraser River, the Upper Fraser, Middle Fraser, South Thompson River and Lower Fraser stocks were inferred to currently be sequentially important sources of Chinook salmon prey through the summer. This information will be of significant value in guiding management actions to recover the southern resident killer whale population.
FULL PAPER HERE

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Herman, David P., Craig O. Matkin, Gina M.Ylitalo, John W. Durban, M. Bradley Hanson, Marilyn E. Dahlheim, Janice M. Straley, Paul R. Wade, Karen L. Tilbury, Richard H. Boyer, Ronald W. Pearce, Margaret M. Krahn (2008). Assessing age distributions of killer whale Orcinus orca populations from the composition of endogenous fatty acids in their outer blubber layers Mar Ecol Prog Ser Vol. 372: 289-302, 2008

ABSTRACT

Knowledge of the age distributions of killer whale Orcinus orca populations is critical to assess their status and long-term viability. Except for accessible, well-studied populations for which historical sighting data have been collected, currently there is no reliable benign method to determine the specific age of live animals for remote populations. To fill this gap in our knowledge of age structure, we describe new methods by which age can be deduced from measurements of specific lipids, endogenous fatty acids (FAs) and FA ratios present in their outer blubber layers. Whereas correlation of wax and sterol esters with age was reasonable for female "resident" killer whales, it was less well-defined for males and "transients." Individual short-, branched-, and odd-chain FAs correlated better with age for transients and residents of both sexes, but these single parameter relationships were population specific and seemingly varied with long-term diet. Alternatively, a simple, empirical multi-linear model derived from the combination of 2 specific FA ratios enabled the ages of individual eastern North Pacific killer whales to be predicted with good precision (σ = ±3.8 yr), appeared to be independent of individual diet and was applicable to both genders and ecotypes. The model was applied to several less well-studied killer whale populations to predict their age distributions from their blubber FA compositions, and these distributions were compared with a population of known age structure. Most interestingly, these results provide evidence for the first time that adult male transient killer whales appear to have lower life expectancies than do their resident counterparts in Alaska. FULL PAPER HERE

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Hickie, Brendan E., Peter S. Ross, Robie W. Macdonald, and John K. B. Ford (2007). Killer Whales (Orcinus orca) Face Protracted Health Risks Associated with Lifetime Exposure to PCBs. Environ. Sci. Technol., 41 (18), 6613 -6619.

ABSTRACT

Polychlorinated biphenyl (PCB) concentrations declined rapidly in environmental compartments and most biota following implementation of regulations in the 1970s. However, the metabolic recalcitrance of PCBs may delay responses to such declines in large, long-lived species, such as the endangered and highly PCB-contaminated resident killer whales (Orcinus orca) of the Northeastern Pacific Ocean. To investigate the influence of life history on PCB-related health risks, we developed models to estimate PCB concentrations in killer whales during the period from 1930 forward to 2030, both within a lifetime (~50 years) and across generations, and then evaluated these in the context of health effects thresholds established for marine mammals. Modeled PCB concentrations in killer whales responded slowly to changes in loadings to the environment as evidenced by slower accumulation and lower magnitude increases in PCB concentrations relative to prey, and a delayed decline that was particularly evident in adult males. Since PCBs attained peak levels well above the effects threshold (17 mg/kg lipid) in ~1969, estimated concentrations in both the northern and the more contaminated southern resident populations have declined gradually. Projections suggest that the northern resident population could largely fall below the threshold concentration by 2030 while the endangered southern residents may not do so until at least 2063. Long-lived aquatic mammals are therefore not protected from PCBs by current dietary residue guidelines.

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Hoelzel, A. Rus, Hey J, Dahlheim ME, Nicholson C, Burkanov V, Black N. (2007). Evolution of population structure in a highly social top predator, the killer whale.. Mol Biol Evol. 2007 Jun;24(6):1407-15.

ABSTRACT

Intraspecific resource partitioning and social affiliations both have the potential to structure populations, though it is rarely possible to directly assess the impact of these mechanisms on genetic diversity and population divergence. Here, we address this for killer whales (Orcinus orca), which specialize on prey species and hunting strategy and have long-term social affiliations involving both males and females. We used genetic markers to assess the structure and demographic history of regional populations and test the hypothesis that known foraging specializations and matrifocal sociality contributed significantly to the evolution of population structure. We find genetic structure in sympatry between populations of foraging specialists (ecotypes) and evidence for isolation by distance within an ecotype. Fitting of an isolation with migration model suggested ongoing, low-level migration between regional populations (within and between ecotypes) and small effective sizes for extant local populations. The founding of local populations by matrifocal social groups was indicated by the pattern of fixed mtDNA haplotypes in regional populations. Simulations indicate that this occurred within the last 20,000 years (after the last glacial maximum). Our data indicate a key role for social and foraging behavior in the evolution of genetic structure among conspecific populations of the killer whale. On line.

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Hoelzel, A. Rus (1991). Killer whale predation on marine mammals at Punta Norte, Argentina; food sharing, provisioning and foraging strategy. Proc. Royal Soc. B 269: 1467-1475.

ABSTRACT

The social dynamics of killer whales (Orcinus orca) that hunt marine mammals are apparently highly flexible, though strong individual associations do exist. The killer whales at Punta Norte offer an unusually detailed view of association patterns and foraging behaviour, and suggest a pattern of behaviour that optimizes hunting efficiency with exception only to strong associations between some individuals and the provisioning and training of offspring. The main points from this paper are as follows: First, hunting effort was concentrated where the capture rate was greatest. All pods selectively attacked the prey type for which they had the highest capture rate. The amount of southern sea lion prey captured was approximately equal to the estimated minimum energetic requirement for killer whales based on weight. Secondly, one whale in each pod did the majority of the hunting, and then provisioned the others in the pod. It was clear on numerous occasions that food was shared. A review of reported incidences of killer wales taking marine mammal prey suggests that it is common for a subset of the individuals in a pod to hunt. These results are discussed in the context of the evolution of foraging behaviour.

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Hoelzel, A. Rus, Ada Natoli, Marilyn E. Dahlheim, Carlos Olavarria, Robin W. Baird and Nancy A. Black (2002). Low worldwide genetic diversity in the killer whale (Orcinus orca): implications for demographic history. Proc. Royal Soc. B 269: 1467-1475.

ABSTRACT

A low level of genetic variation in mammalian populations where the census population size is relatively large has been attributed to various factors, such as a naturally small effective population size, historical bottlenecks and social behaviour. The killer whale (Orcinus orca) is an abundant, highly social species with reduced genetic variation. We find no consistent geographical pattern of global diversity and no mtDNA variation within some regional populations. The regional lack of variation is likely to be due to the strict matrilineal expansion of local populations. The worldwide pattern and paucity of diversity may indicate a historical bottleneck as an additional factor. Full paper.

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Ivkovicha, Tatiana, Olga A. Filatovab, Alexandr M. Burdinc, Hal Satoe and Erich Hoyt (2009). The social organization of resident-type killer whales (Orcinus orca) in Avacha Gulf, Northwest Pacific, as revealed through association patterns and acoustic similarity Mammalian Biology.

ABSTRACT

Northeast Pacific resident-type killer whales (Orcinus orca) are known to form stable associations based on kinship between maternal relatives (matrilines) with a system of vocal dialects thought to reflect kinship relationships. We analyzed association patterns and acoustic similarity to study the social organization of killer whales in Avacha Gulf (Kamchatka, Russia), in the Northwest Pacific. The resident-type killer whales of Avacha Gulf formed temporally stable units that included maternal relatives with no dispersal observed. Acoustically, the killer whale community of Avacha Gulf was characterized by a system of dialects comparable to the communities of Northeast Pacific resident-type killer whales. Different units rarely associated with each other and these associations were nonrandom. Associations at different spatial levels did not always coincide with each other and with the patterns of acoustic similarity. Associations between units could change quickly irrespective of kinship relationships. The vocal dialect of a unit, which is more stable than the association patterns between units, might better reflect the overall kinship relationships. The stability and frequency of associations between units depended on the number of mature males in a unit, which could contribute to differences in the speed of change in vocal dialects and association patterns.

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Johnstone, Rufus A., and Michael A. Cant (2010). The evolution of menopause in cetaceans and humans: the role of demography , Proc. R. Soc. B published online before print June 30, 2010, doi:10.1098/rspb.2010.0988

ABSTRACT

Human females stop reproducing long before they die. Among other mammals, only pilot and killer whales exhibit a comparable period of post-reproductive life. The grandmother hypothesis suggests that kin selection can favour post-reproductive survival when older females help their relatives to reproduce. But although there is an evidence that grandmothers can provide such assistance, it is puzzling why menopause should have evolved only among the great apes and toothed whales. We have previously suggested (Cant & Johnstone 2008 Proc. Natl Acad. Sci. USA 105, 5332-5336 (doi:10.1073/pnas.0711911105)) that relatedness asymmetries owing to female-biased dispersal in ancestral humans would have favoured younger females in reproductive competition with older females, predisposing our species to the evolution of menopause. But this argument appears inapplicable to menopausal cetaceans, which exhibit philopatry of both sexes combined with extra-group mating. Here, we derive general formulae for "kinship dynamics," the age-related changes in local relatedness that occur in long-lived social organisms as a consequence of dispersal and mortality. We show that the very different social structures of great apes and menopausal whales both give rise to an increase in local relatedness with female age, favouring late-life helping. Our analysis can therefore help to explain why, of all long-lived, social mammals, it is specifically among the great apes and toothed whales that menopause and post-reproductive helping have evolved.
FULL PAPER

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Krahn, Margaret M., M. Bradley Hanson, Gregory S. Schorr, Candice K. Emmons, Douglas G. Burrows, Jennie L. Bolton, Robin W. Baird, Gina M. Ylitalo (2009). Effects of age, sex and reproductive status on persistent organic pollutant concentrations in "Southern Resident" killer whales Mar. Pollut. Bull. (2009), doi:10.1016/j.marpolbul.2009.05.014.

ABSTRACT

"Southern Resident" killer whales (Orcinus orca) that comprise three fish-eating "pods" (J, K and L) were listed as "endangered" in the US and Canada following a 20% population decline between 1996 and 2001. Blubber biopsy samples from Southern Resident juveniles had statistically higher concentrations of certain persistent organic pollutants than were found for adults. Most Southern Resident killer whales, including the four juveniles, exceeded the health-effects threshold for total PCBs in marine mammal blubber. Maternal transfer of contaminants to the juveniles during rapid development of their biological systems may put these young whales at greater risk than adults for adverse health effects (e.g., immune and endocrine system dysfunction). Pollutant ratios and field observations established that two of the pods (K- and L-pod) travel to California to forage. Nitrogen stable isotope values, supported by field observations, indicated possible changes in the diet of L-pod over the last decade.
FULL PAPER

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Krahn, Margaret M., M. Bradley Hanson, Robin W. Baird, Richard H. Boyer, Douglas G. Burrows, Candice K. Emmons, John K.B. Ford, Linda L. Jones, Dawn P. Noren, Peter S. Ross, Gregory S. Schorr, Tracy K. Collier (2007). Persistent organic pollutants and stable isotopes in biopsy samples (2004/2006) from Southern Resident killer whales, Marine Pollution Bulletin xxx (2007) xxx-xxx.

ABSTRACT

"Southern Resident" killer whales include three "pods" (J, K and L) that reside primarily in Puget Sound/Georgia Basin during the spring, summer and fall. This population was listed as "endangered" in the US and Canada following a 20% decline between 1996 and 2001. The current study, using blubber/epidermis biopsy samples, contributes contemporary information about potential factors (i.e., levels of pollutants or changes in diet) that could adversely affect Southern Residents. Carbon and nitrogen stable isotopes indicated J- and L-pod consumed prey from similar trophic levels in 2004/2006 and also showed no evidence for a large shift in the trophic level of prey consumed by L-pod between 1996 and 2004/2006. ΣPPCBs decreased for Southern Residents biopsied in 2004/2006 compared to 1993-1995. Surprisingly, however, a three-year-old male whale (J39) had the highest concentrations of ΣPPBDEs, ΣPHCHs and HCB. POP ratio differences between J- and L-pod suggested that they occupy different ranges in winter.
FULL PAPER

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Krützen, Michael, Janet Mann, Michael R. Heithaus, Richard C. Connor, Lars Bejder, and William B. Sherwin (2005). Cultural transmission of tool use in bottlenose dolphins PNAS, June 21, 2005, vol. 102, no. 25, 8939-8943.

ABSTRACT

In Shark Bay, wild bottlenose dolphins (Tursiops sp.) apparently use marine sponges as foraging tools. We demonstrate that genetic and ecological explanations for this behavior are inadequate; thus, "sponging" classifies as the first case of an existing material culture in a marine mammal species. Using mitochondrial DNA analyses, we show that sponging shows an almost exclusive vertical social transmission within a single matriline from mother to female offspring. Moreover, significant genetic relatedness among all adult spongers at the nuclear level indicates very recent coancestry, suggesting that all spongers are descendents of one recent "Sponging Eve." Unlike in apes, tool use in this population is almost exclusively limited to a single matriline that is part of a large albeit open social network of frequently interacting individuals, adding a new dimension to charting cultural phenomena among animals.

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Kuczaj, Stan A., Radhika Makecha, Marie Trone, Robin D. Paulos, and Joana A. Ramos (2006). Role of Peers in Cultural Innovation and Cultural Transmission: Evidence from the Play of Dolphin Calves International Journal of Comparative Psychology, 2006, 19, 223-240.

ABSTRACT
Observations of the spontaneous play behaviors of a group of captive bottlenose dolphins (Tursiops truncatus) revealed that each individual calf's play became more complex with increasing age, suggesting that dolphin play may facilitate the ontogeny and maintenance of flexible problem solving skills. If this is so, play may have evolved to help young dolphins learn to adapt to novel situations. Novel play behaviors were more likely to be produced by dolphin calves than by adults, demonstrating that calves were the main source of innovative play behaviors in the group. Calves were also more likely to imitate novel play behaviors first produced by another dolphin, suggesting that calves contribute significantly to the spread of novel behaviors within a group. All in all, these data suggest that peers may be important catalysts for both cultural innovation and cultural transmission, and that the opportunity to interact with peers may enhance the effect play has on the emergence of flexible problem solving skills.
Correspondence concerning this article should be addressed to Stan Kuczaj, University of Southern Mississippi, 118 College Drive, 5025, Hattiesburg, MS, 39406, U.S.A. (s.kuczaj@usm.edu).

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LeDuc, Richard G., Kelly M. Robertson, and Robert L. Pitman (2008). Mitochondrial sequence divergence among Antarctic killer whale ecotypes is consistent with multiple species Biol. Lett. (2008) 4, 426-429.

ABSTRACT
Recently, three visually distinct forms of killer whales (Orcinus orca) were described from Antarctic waters and designated as types A, B and C. Based on consistent differences in prey selection and habitat preferences, morphological divergence and apparent lack of interbreeding among these broadly sympatric forms, it was suggested that they may represent separate species. To evaluate this hypothesis, we compared complete sequences of the mitochondrial control region from 81 Antarctic killer whale samples, including 9 type A, 18 type B, 47 type C and 7 typeundetermined individuals. We found three fixed differences that separated type A from B and C, and a single fixed difference that separated type C from A and B. These results are consistent with reproductive isolation among the different forms, although caution is needed in drawing further conclusions. Despite dramatic differences in morphology and ecology, the relatively low levels of sequence divergence in Antarctic killer whales indicate that these evolutionary changes occurred relatively rapidly and recently. Full paper.

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Lyamina, Oleg I., Paul R. Manger,, Sam H. Ridgway, Lev M. Mukhametov and Jerome M. Siegel (2008). Cetacean sleep: An unusual form of mammalian sleep Neuroscience & Biobehavioral Reviews Volume 32, Issue 8, October 2008, Pages 1451-1484.

ABSTRACT
Our knowledge of the form of lateralized sleep behavior, known as unihemispheric slow wave sleep (USWS), seen in all members of the order Cetacea examined to date, is described. We trace the discovery of this phenotypically unusual form of mammalian sleep and highlight specific aspects that are different from sleep in terrestrial mammals. We find that for cetaceans sleep is characterized by USWS, a negligible amount or complete absence of rapid eye movement (REM) sleep, and a varying degree of movement during sleep associated with body size, and an asymmetrical eye state. We then compare the anatomy of the mammalian somnogenic system with what is known in cetaceans, highlighting areas where additional knowledge is needed to understand cetacean sleep. Three suggested functions of USWS (facilitation of movement, more efficient sensory processing and control of breathing) are discussed. Lastly, the possible selection pressures leading to this form of sleep are examined, leading us to the suggestion that the selection pressure necessitating the evolution of cetacean sleep was most likely the need to offset heat loss to the water from birth and throughout life. Aspects such as sentinel functions and breathing are likely to be proximate evolutionary phenomenon of this form of sleep.

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Marino, Lori, Toni Frohoff (2011). Towards a New Paradigm of Non-Captive Research on Cetacean Cognition PLoS ONE 6(9): e24121. doi:10.1371/journal.pone.0024121.

ABSTRACT

Contemporary knowledge of impressive neurophysiology and behavior in cetaceans, combined with increasing opportunities for studying free-ranging cetaceans who initiate sociable interaction with humans, are converging to highlight serious ethical considerations and emerging opportunities for a new era of progressive and less-invasive cetacean research. Most research on cetacean cognition has taken place in controlled captive settings, e.g., research labs, marine parks. While these environments afford a certain amount of experimental rigor and logistical control they are fraught with limitations in external validity, impose tremendous stress on the part of the captive animals, and place burdens on populations from which they are often captured. Alternatively, over the past three decades, some researchers have sought to focus their attention on the presence of free-ranging cetacean individuals and groups who have initiated, or chosen to participate in, sociable interactions with humans in the wild. This new approach, defined as Interspecies Collaborative Research between cetacean and human, involves developing novel ways to address research questions under natural conditions and respecting the individual cetacean's autonomy. It also offers a range of potential direct benefits to the cetaceans studied, as well as allowing for unprecedented cognitive and psychological research on sociable mysticetes. Yet stringent precautions are warranted so as to not increase their vulnerability to human activities or pathogens. When conducted in its best and most responsible form, collaborative research with free-ranging cetaceans can deliver methodological innovation and invaluable new insights while not necessitating the ethical and scientific compromises that characterize research in captivity. Further, it is representative of a new epoch in science in which research is designed so that the participating cetaceans are the direct recipients of the benefits.

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Lefebvre, L, Marino, L., Sol, D, Lemieux S, Arshad, S. (2006). Large brains and lengthened life history periods in odontocetes Brain Behavior and Evolution. 268: 218-228.

ABSTRACT

Previous work on primates and birds suggests that large brains require longer periods of juvenile growth, leading to reproductive constraints due to delayed maturation. We examined the relationship between brain size and life history periods in cetaceans, a large-brained mammalian order that has been largely ignored. We looked at males and females of twenty-five species of odontocetes, using independent contrasts and multiple regressions to disentangle possible phylogenetic effects and inter-correlations among life history traits. We corrected all variables for body size allometry and separated life span into adult and juvenile periods. For females and both sexes combined, gestation, time to sexual maturity, time as an adult and life span were all positively associated with residual brain size in simple regressions; in multiple regressions maximum life span and time as an adult were the best predictors of brain size. Males showed few significant trends. Our results suggest that brain size has co-evolved with extended life history periods in odontocetes, as it has in primates and birds, and that a lengthened adult period could have been an important component of encephalization in cetaceans. Full paper.

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Marino, Lori, Camilla Butti, Richard C. Connor, R. Ewan Fordyce, Louis M. Herman, Patrick R. Hof, Louis Lefebvre, David Lusseau, Brenda McCowan, Esther A. Nimchinsky, Adam A. Pack, Joy S. Reidenberg, Diana Reiss, Luke Rendell, Mark D. Uhen, Estelle Van der Gucht, and Hal Whitehead (2008). A claim in search of evidence: reply to Manger's thermogenesis hypothesis of cetacean brain structure Biological Reviews doi:10.1111/j.1469-185X.2008.00049.x.

ABSTRACT

In a recent publication in Biological Reviews, Manger (2006) made the controversial claim that the large brains of cetaceans evolved to generate heat during oceanic cooling in the Oligocene epoch and not, as is the currently accepted view, as a basis for an increase in cognitive or information-processing capabilities in response to ecological or social pressures. Manger further argued that dolphins and other cetaceans are considerably less intelligent than generally thought. In this review we challenge Manger's arguments and provide abundant evidence that modern cetacean brains are large in order to support complex cognitive abilities driven by social and ecological forces. FULL PAPER HERE.

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Marino, Lori; Richard C. Connor, R. Ewan Fordyce, Louis M. Herman, Patrick R. Hof, Louis Lefebvre, David Lusseau, Brenda McCowan, Esther A. Nimchinsky, Adam A. Pack, Luke Rendell, Joy S. Reidenberg, Diana Reiss, Mark D. Uhen, Estel Van der Gucht, Hal Whitehead. Cetaceans Have Complex Brains for Complex Cognition PLos Biol 5(5): e139 doi:10.1371/journal.pbio.0050139. 2007.

ABSTRACT

The brain of a sperm whale is about 60% larger in absolute mass than that of an elephant. Furthermore, the brains of toothed whales and dolphins are significantly larger than those of any nonhuman primates and are second only to human brains when measured with respect to body size [1]. How and why did such large brains evolve in these modern cetaceans? One current view of the evolution of dolphin brains is that their large size was primarily a response to social forces-the requirements for effective functioning within a complex society characterized by communication and collaboration as well as competition among group members [2-4]. In such a society, individuals can benefit from the recognition of others and knowledge of their relationships and from flexibility in adapting to or implementing new behaviors as social or ecological context shifts. Other views focus on the cognitive demands associated with the use of echolocation [5-7].

Recently, Manger [8] made the controversial claim that cetacean brains are large because they contain an unusually large number of thermogenic glial cells whose numbers increased greatly to counteract heat loss during a decrease in ocean temperatures in the Eocene-Oligocene transition. Therefore, he argues, cetacean brain size could have evolved independently of any cognitive demands and, further, that there is neither neuronal evidence nor behavioral evidence of complex cognition in cetaceans. These claims have garnered considerable attention in the popular press, because they challenge prevailing knowledge and understanding of cetacean brain evolution, cognition, and behavior.

We believe that the time is ripe to present an integrated view of cetacean brains, behavior, and evolution based on the wealth of accumulated and recent data on these topics. Our conclusions support the more generally accepted view that the large brain of cetaceans evolved to support complex cognitive abilities.

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Marino, Lori; Chet C. Sherwood, Bradley N. Delman, Cheuk Y. Tang, Thomas P. Naidich, Patrick R. Hof. Neuroanatomy of the killer whale (Orcinus orca) from magnetic resonance images Anat Rec 281A, 2:1256-1263 264:397-414, 2004.

ABSTRACT

This article presents the first series of MRI-based anatomically labeled sectioned images of the brain of the killer whale (Orcinus orca). Magnetic resonance images of the brain of an adult killer whale were acquired in the coronal and axial planes. The gross morphology of the killer whale brain is comparable in some respects to that of other odontocete brains, including the unusual spatial arrangement of midbrain structures. There are also intriguing differences. Cerebral hemispheres appear extremely convoluted and, in contrast to smaller cetacean species, the killer whale brain possesses an exceptional degree of cortical elaboration in the insular cortex, temporal operculum, and the cortical limbic lobe. The functional and evolutionary implications of these features are discussed.
Full paper HERE.

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Marino, Lori; Keith D. Sudheimer, Timothy L. Murphy, Kristina K. Davis, D. Ann Pabst, William A. McLellan, James K. Rilling, John I. Johnson. 2001. Anatomy and three-dimensional reconstructions of the brain of a bottlenose dolphin (Tursiops truncatus) from magnetic resonance images Anat Rec 264:397-414.

ABSTRACT

Cetacean (dolphin, whale, and porpoise) brains are among the least studied mammalian brains because of the formidability of collecting and histologically preparing such relatively rare and large specimens. Magnetic resonance imaging offers a means of observing the internal structure of the brain when traditional histological procedures are not practical. Furthermore, internal structures can be analyzed in their precise anatomic positions, which is difficult to accomplish after the spatial distortions often accompanying histological processing. In this study, images of the brain of an adult bottlenose dolphin, Tursiops truncatus, were scanned in the coronal plane at 148 antero-posterior levels. From these scans a computer-generated three-dimensional model was constructed using the programs VoxelView and VoxelMath (Vital Images, Inc.). This model, wherein details of internal and external morphology are represented in three-dimensional space, was then resectioned in orthogonal planes to produce corresponding series of virtual sections in the horizontal and sagittal planes. Sections in all three planes display the sizes and positions of major neuroanatomical features such as the arrangement of cortical lobes and subcortical structures such as the inferior and superior colliculi, and demonstrate the utility of MRI for neuroanatomical investigations of dolphin brains.

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Mate, B. (1989a). Satellite-Monitored Radio Tracking as a Method for Studying Cetacean Movements and Behaviour. Sci. Rep Int. Whale Commn. Vol. 40, p. 389-391.

Note: In summer 1987, a pilot whale tagged with an Argos satellite-monitored radio tag was tracked for 95 days in the western North Atlantic. The whale was located 479 times by satellite during movements of at least 7,588 km and sighted from an aircraft several times in the company of other pilot whales. Duration of dive data were collected on 187,866 dives. Transmitter temperature information was also sent and indicated that virtually all deep dives occurred at night, when the whale was likely feeding on squid. Surface resting occurred most often immediately after sunrise on a four-to seven-day cycle. Future movement and dive information in conjunction with oceanographic data will be important in identifying the critical habitats of whales and understanding their behavior. Satellites offer an important new cost-effective tool for studying whales.

The technology existed as of 1989 to satellite tag released whales and track them over long distances for significantly long periods of time. Dr. Mate has also satellite tagged bowhead whales and bottlenosed dolphins with good success. Two other pilot whales attached with radio tags in 1991 were sighted in February 1994 with harnesses still attached.

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Matkin, C. O., E. L. Saulitis, G. M. Ellis, P. Olesiuk, S. D. Rice 2008. Ongoing population-level impacts on killer whales Orcinus orca following the "Exxon Valdez" oil spill in Prince William Sound, Alaska (2008). Mar Ecol Prog Ser., Vol. 356: 269-281, 2008
ABSTRACT

Killer whales were photographed in oil after the 1989 "Exxon Valdez" oil spill, but preliminary damage assessments did not definitively link mortalities to the spill and could not evaluate recovery. In this study, photo-identification methods were used to monitor 2 killer whale populations 5 yr prior to and for 16 yr after the spill. One resident pod, the AB Pod, and one transient population, the AT1 Group, suffered losses of 33 and 41%, respectively, in the year following the spill. Sixteen years after 1989, AB Pod had not recovered to pre-spill numbers. Moreover, its rate of increase was significantly less than that of other resident pods that did not decline at the time of the spill. The AT1 Group, which lost 9 members following the spill, continued to decline and is now listed as depleted under the Marine Mammal Protection Act. Although there may be other contributing factors, the loss of AT1 individuals, including reproductive-age females, accelerated the population's trajectory toward extinction. The synchronous losses of unprecedented numbers of killer whales from 2 ecologically and genetically separate groups and the absence of other obvious perturbations strengthens the link between the mortalities and lack of recovery, and the "Exxon Valdez" oil spill.

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McAuliffe, Katherine and Hal Whitehead. 2005. Eusociality, menopause and information in matrilineal whales. TRENDS in Ecology and Evolution Vol.20 No.12 December 2005
ARTICLE

In their recent article in TREE, Foster and Ratnieks make the interesting proposal that humans should be considered 'eusocial' on the grounds that females spend a substantial part of their adult life reproductively sterile and help their close relatives. The authors consider that menopause, in this sense of the term, is unique among vertebrates to humans. However, female shortfinned pilot whales Globicephala macrorhynchus, killer whales Orcinus orca, and probably a few other species of cetacean, such as sperm whales Physeter macrocephalus, have menopause with similar attributes to human females. In all these species, reproduction ceases at approximately 40 years of age, although females routinely live on for several more decades. Thus, cetaceans can also be considered eusocial if the term can be used in the context of within-individual classes of reproductives and sterile helpers.
The cetacean species in which menopause is known or probable all have matrilineal social systems in the sense that most of the females spend their lives grouped with their mothers when both are alive. This correlation, and the presence of menopause in these cetaceans which (unlike modern humans) have not faced a dramatic recent change in their living conditions, strongly indicate that menopause is adaptive, and results from the tradeoff between continued reproduction and assisting kin. Given that menopause invariably occurs in these species, the benefits of assisting kin must outweigh the costs of reproductive cessation. What is not clear, however, is how these menopausal grandmothers help. Among menopausal cetaceans, assistance in foraging is not seen, and at least in killer whales, defence against predators is rare. Similar to human grandmothers, menopausal cetacean females have experience that might benefit other members of their matrilines. The value of this information could explain why females in these species live about a third of their lives as post-reproductive members of their social groups.
The informative role of cetacean grandmothers is consistent with an emerging body of information indicating cultures in matrilineal cetacean species. Thus, in both cetaceans and humans, the storage and provision of information might be the primary function of menopausal females and, thus, the driver of eusociality.

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McGowen, Michael R., Michelle Spaulding, John Gatesy. 2009. Divergence date estimation and a comprehensive molecular tree of extant cetaceans Molecular Phylogenetics and Evolution 53 (2009) 891-906
ABSTRACT

Cetaceans are remarkable among mammals for their numerous adaptations to an entirely aquatic existence, yet many aspects of their phylogeny remain unresolved. Here we merged 37 new sequences from the nuclear genes RAG1 and PRM1 with most published molecular data for the group (45 nuclear loci, transposons, mitochondrial genomes), and generated a supermatrix consisting of 42,335 characters. The great majority of these data have never been combined. Model-based analyses of the supermatrix produced a solid, consistent phylogenetic hypothesis for 87 cetacean species. Bayesian analyses corroborated odontocete (toothed whale) monophyly, stabilized basal odontocete relationships, and completely resolved branching events within Mysticeti (baleen whales) as well as the problematic speciose clade Delphinidae (oceanic dolphins). Only limited conflicts relative to maximum likelihood results were recorded, and discrepancies found in parsimony trees were very weakly supported. We utilized the Bayesian supermatrix tree to estimate divergence dates among lineages using relaxed-clock methods. Divergence estimates revealed rapid branching of basal odontocete lineages near the Eocene–Oligocene boundary, the antiquity of river dolphin lineages, a Late Miocene radiation of balaenopteroid mysticetes, and a recent rapid radiation of Delphinidae beginning 10 million years ago. Our comprehensive, timecalibrated tree provides a powerful evolutionary tool for broad-scale comparative studies of Cetacea.
"Here Orcinus orca (killer whale), the largest delphinid, and Leucopleurus acutus (Atlantic white-sided dolphin) were basal delphinids in all model-based analyses"
FULL PAPER HERE

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McSweeney, D.J., R.W. Baird, S.D. Mahaffy, D.L.Webster and G.S. Schorr. 2008. Site fidelity and association patterns of a rare species: pygmy killer whales (Feresa attenuata) in the main Hawaiian Islands. Marine Mammal Science DOI: 10.1111/j.1748-7692.2008.00267.x.
ABSTRACT

Most of what we know about cetacean biology and ecology comes from studies of relatively common species. Despite their distribution throughout the tropics and sub-tropics, pygmy killer whales (Feresa attenuata) are rare throughout their range and are one of the most poorly-known species of odontocetes. During a 22-year study of short-finned pilot whales (Globicephala macrorhynchus) off the island of Hawai'i, we opportunistically photo-identified pygmy killer whales whenever encountered. As part of a directed multi-species study throughout the main Hawaiian Islands from 2000 through 2007, we also photo-identified individuals and obtained information on habitat use and behavior. This species was extremely uncommon (representing only 1.2% of odontocete sightings in directed efforts). Given the low encounter rates, assessing trends of this population cannot be feasibly done with line-transect surveys. Despite their rarity, 80% of the distinctive individuals within groups documented off the island of Hawai'i were seen on multiple occasions, individuals were re-sighted over periods of up to 21 yr, and there was evidence of year-round use of the area. Association analyses indicate stable long-term associations in mixed-sex groups. High re-sighting rates indicate a small population of island-associated individuals that may be at risk from anthropogenic impacts.
More information and photographs are available HERE



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Miller, Lee A., 2006. Killer Whales and Herring: Using Sound to Get a Meal. 151st ASA Meeting, Providence, RI.
PRESENTATION

Norwegian and Icelandic killer whales use a variety of techniques to get their dinner, many of which are acoustic. In defense, their prey employ clever acoustical countermeasures of their own. Icelandic killer whales, as we have discovered, employ an additional strategy, apparently not shared by their Norwegian cousins, that may give them an extra advantage in capturing their prey.

Killer whales of the Northeast Atlantic feed primarily on herring. In Norwegian waters billions of herring migrate from open oceanic waters into deep fjords in the late fall to over winter. Here they form vast schools that move up and down in the water column in daily rhythms "waiting" for spring to approach. In February, they migrate about 1,000 km south to their spawning grounds, and then out to open waters again. Groups of killer whales follow the herring to cooperatively feed on this favored prey. Often the whales dive to over a hundred meters to drive herring up to shallower waters forcing the fish into tight groups by swimming around them and flashing their white bellies at them.

Complete paper online HERE.

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Miller, Patrick J., 2006. Diversity in sound pressure levels and estimated active space of resident killer whale vocalizations. J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2006 May;192(5):449-59.
ABSTRACT

Signal source intensity and detection range, which integrates source intensity with propagation loss, background noise and receiver hearing abilities, are important characteristics of communication signals. Apparent source levels were calculated for 819 pulsed calls and 24 whistles produced by free-ranging resident killer whales by triangulating the angles-of-arrival of sounds on two beamforming arrays towed in series. Levels in the 1-20 kHz band ranged from 131 to 168 dB re 1 microPa at 1 m, with differences in the means of different sound classes (whistles: 140.2+/-4.1 dB; variable calls: 146.6+/-6.6 dB; stereotyped calls: 152.6+/-5.9 dB), and among stereotyped call types. Repertoire diversity carried through to estimates of active space, with "long-range" stereotyped calls all containing overlapping, independently-modulated high-frequency components (mean estimated active space of 10-16 km in sea state zero) and "short-range" sounds (5-9 km) included all stereotyped calls without a high-frequency component, whistles, and variable calls. Short-range sounds are reported to be more common during social and resting behaviors, while long-range stereotyped calls predominate in dispersed travel and foraging behaviors. These results suggest that variability in sound pressure levels may reflect diverse social and ecological functions of the acoustic repertoire of killer whales. On line

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Morin, Phillip A., Frederick I Archer, Andrew D Foote, Julie Vilstrup, Eric E Allen, Paul Wade, John Durban, Kim Parsons, Robert Pitman, Lewyn Li, Pascal Bouffard, Sandra C Abel Nielsen, Morten Rasmussen, Eske Willerslev, M. Thomas P Gilbert and Timothy Harkins Complete mitochondrial genome phylogeographic analysis of killer whales (Orcinus orca) indicates multiple species. Genome Research April 2010, 20 (4)

ABSTRACT

Killer whales (Orcinus orca) currently comprise a single, cosmopolitan species with a diverse diet. However, studies over the last 30 years have revealed populations of sympatric "ecotypes" with discrete prey preferences, morphology and behaviors. Although these ecotypes avoid social interactions and are not known to interbreed, genetic studies to date have found extremely low levels of diversity in the mitochondrial control region, and few clear phylogeographic patterns worldwide. This low level of diversity is likely due to low mitochondrial mutation rates that are common to cetaceans. Using killer whales as a case study, we have developed a method to readily sequence, assemble, and analyze complete mitochondrial genomes from large numbers of samples to more accurately assess phylogeography and estimate divergence times. This represents an important tool for wildlife management, not only for killer whales but for many marine taxa. We used high-throughput sequencing to survey whole mitochondrial genome variation of 139 samples from the North Pacific, North Atlantic and southern oceans. Phylogenetic analysis indicated that each of the known ecotypes represents a strongly supported clade with divergence times ranging from approximately 150,000 to 700,000 years ago. We recommend that three named ecotypes be elevated to full species, and that the remaining types be recognized as subspecies pending additional data. Establishing appropriate taxonomic designations will greatly aid in understanding the ecological impacts and conservation needs of these important marine predators. We predict that phylogeographic mitogenomics will become an important tool for improved statistical phylogeography and more precise estimates of divergence times. Full paper.

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Morin, Phillip A., Richard G. LeDuc, Kelly M. Robertson, Nicole M. Hedrick, William F. Perrin, Michael Etnier, Paul Wade, Barbara L. Taylor 2006. Genetic analysis of killer whale (Orcinus Orca) historical bone and tooth samples to identify western U.S. ecotypes. Marine Mammal Science, Volume 22 Issue 4 Page 897 - October

ABSTRACT

Little is known about the historical range of killer whale ecotypes in the eastern North Pacific (ENP). It is possible that ranges have shifted in the last few decades because of changes in availability of food. In particular, the southern resident ecotype, currently found primarily in the inland waters of Washington State, is known to prey extensively on salmon, which have declined in recent decades along the outer coasts of Washington, Oregon, and California. To investigate historical distributions of this and the other ENP ecotypes, samples of teeth and bones were obtained from NMFS and museum collections. We amplified a short section of the mitochondrial DNA control region that contains four diagnostic sites that differentiate between haplotypes found in ecotypes of ENP killer whales. Results did not show any southern resident haplotypes in samples from south of the Washington State inland waterways. One whale genetically identified as a northern resident extends the known southernmost distribution of the population from Oregon to California. Items of diet identified from stomach contents of six of the whales genetically identified to ecotype conformed with what is known of the feeding habits of the various ecotypes. Full paper.

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Noad, Michael J; Douglas H. Cato and M.M. Bryden. Cultural displacement and replacement in the songs of Australian humpback whales Nature 408, 537 2000.

ABSTRACT

Song was recorded from Australian east coast humpback whales, Megaptera novaeangliae, during migration in 1995 - 1998. Over 1000 hours of song were used to determine the song pattern in 252 song sessions. While the pattern of the song was initially highly stereotyped, in 1996 two singers were recorded with a completely different song type. During the 1997 migrations the use of the 'new' song type increased dramatically and completely replaced the 'old' song by 1998. The 'new' song type was identical to song from Australian west coast humpback whales recorded in 1996 but identical to song from Australian west coast humpback whales recorded in 1996 but different to that from 1995 or 1997. These results demonstrate that the introduction of west coast song at a very low initial prevalence was able to completely displace the vocal cultural tradition of the east coast population. The process of change in humpback whale song and bird song has been described as 'cultural evolution' whereby changes in songs are passed among individuals by learning and accumulate over time. The song changes described here were cultural, but were revolutionary rather than evolutionary, the cultural vocal pattern of one population displacing and replacing completely that of another population.

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Noren, D. P., A. H. Johnson, D. Rehder, A. Larson 2009. Close approaches by vessels elicit surface active behaviors by southern resident killer whales Endang Species Res 8: 179-192, 2009

ABSTRACT

Vessel disturbance is one potential risk factor to the endangered population of southern resident killer whales Orcinus orca. This study was conducted to determine if southern resident killer whales perform surface active behaviors (SABs) in response to close approaches by vessels. Data were collected in the San Juan Islands, USA, and Gulf Islands, Canada, from May through September 2005 and 2006. Continuous behavioral data, including the performance of SABs (e.g. spy hops, breaches, tail slaps, pectoral fin slaps), were recorded from southern resident killer whales using a focal follow approach. Distances between the focal whale and nearby vessels were systematically measured throughout each focal follow. In addition, the distance between the nearest vessel and the focal whale was recorded each time the whale performed an SAB. Tail slaps were the most frequently performed SAB. The highest frequency of SABs occurred when the nearest vessel was within 75 to 99 m and 125 to 149 m of the focal whale in 2005 and 2006, respectively. Approximately 70% of SABs occurred when the closest vessel was within 224 m of the whale. Furthermore, a significantly greater proportion of SABs occurred when vessels closely approached whales. Finally, there was a significant temporal relationship between close approaches and the occurrence of SABs; most SABs were performed near the time of the closest approach by a vessel. These results suggest that close approaches by vessels elicit behavioral responses in southern resident killer whales and that the minimum approach distance of 100 m in whale-watching guidelines may be insufficient in preventing behavioral responses from whales.

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Norman, S.A., Raverty, S., McLellan, B., Pabst, A., Ketten, D., Fleetwood, M., Gaydos, J.K., Norberg, B., Barre, L., Cox, T., Hanson, B., and Jeffries, S. 2004. Multidisciplinary investigation of stranded harbor porpoises (Phocoena phocoena) in Washington State with an assessment of acoustic trauma as a contributory factor (2 May - 2 June 2003) U.S. Dep. Commerce, NOAA Tech. Memo. NMFS-NWR-34, 120 p.

ABSTRACT

Observations of altered behavior of marine mammals in the area of mid-range sonar use by the naval vessel USS SHOUP in the eastern Strait of Juan de Fuca and Haro Strait on 5 May 2003, prompted the National Marine Fisheries Service (NMFS) to conduct an in-depth investigation on the causes of harbor porpoise strandings. Fifteen stranded harbor porpoises were reported during the period of 2 May 2003 to 2 June 2003, an abnormally high number when compared to the average stranding rate of 6 per year recorded over the previous decade. Eleven of the stranded harbor porpoises were collected for this investigation.
NMFS assembled a multidisciplinary team to conduct extensive classical forensic necropsy examinations on the 11 specimens, followed by laboratory diagnostic and histological analyses and complemented by high resolution computerized tomography (CT) scans. Samples were taken for a variety of analyses including disease screening, parasitology, chemical contaminant and lipid analyses, aging studies, prey identification and domoic acid analysis. The gross and microscopic findings from the necropsy examinations, laboratory results, and the analysis of the CT image data for each specimen are provided. Information on the discovery and collection of the stranded porpoises, and a comparison of this with porpoise strandings over the previous ten years is also included in this report.
Over 70 percent of the specimens were in moderate to advanced states of decomposition which made interpretation of the cause of death difficult. The cause of death was determined for five of the 11 porpoises examined by the multidisciplinary team. Of these five animals, two were found to have suffered blunt force trauma, while illness (peritonitis, salmonellosis, pneumonia) was implicated in the remaining three cases. No cause of death could be determined for the remaining six animals. The examinations did not reveal definitive signs of acoustic trauma in any of the porpoises examined. The multidisciplinary team noted that lesions consistent with acoustic trauma can be difficult to interpret or obscured, especially in animals in advanced postmortem decomposition. Because many of the carcasses investigated were in moderate to poor condition, the possibility of acoustic trauma from exposure to mid-range sonar as a contributory factor in the mortality of any of the porpoises could not be ruled out.

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Nousek, Anna E., Peter J.B. Slater, Chao Wang, Patrick J.O. Miller.2006. The influence of social affiliation on individual vocal signatures of northern resident killer whales (Orcinus orca) Royal Society Journal

ABSTRACT

Northern resident killer whales (Orcinus orca) live in highly stable groups and use group-specific vocal signals, but individual variation in calls has not been described previously. A towed beam-forming array was used to ascribe stereotyped pulsed calls with two independently modulated frequency contours to visually identified individual killer whales in Johnstone Strait, British Columbia. Overall, call similarity determined using neural networks differed significantly between different affiliation levels for both frequency components of all the call types analysed. This method distinguished calls from individuals within the same matriline better than different calls produced by a single individual and than chance. The calls of individuals from different matrilines were more distinctive than those within the same matriline, confirming previous studies based on group recordings. These results show that frequency contours of stereotyped calls differ among the individuals that are constantly associated with each other and use group-specific vocalizations, though across-group differences were substantially more pronounced.

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Olesiuk, P.F., G.M. Ellis and J.K.B Ford (2005). Life History and Population Dynamics of Northern Resident Killer Whales (Orcinus orca) in British Columbia).

ABSTRACT

Annual photo-identification surveys conducted between 1973-75 and 2004 were used to estimate life history parameters and develop a population model for the northern resident population of killer whales that inhabits coastal waters of British Columbia. During the 1970's, 80's and early 90's, the population grew exponentially (r2=0.986; F1,22=1,568.5; P 0.001) at an annual rate of 2.6% (95% CI 2.48-2.76%). Although the population almost doubled in size from about 125 to 217 animals, there was no evidence of a slowing of the growth rate (F1,21=0.25; P=0.622), suggesting the population was unrestrained and increasing at its maximum intrinsic rate. The population peaked abruptly in the mid-1990s, declined by 7-9%, and then exhibited a small increase, resulting in no discernible trend over the last decade (F1,10=1.36; P=0.271), indicating that something was restraining its growth. Life history and population parameters were thus estimated separately for 1973-96, a period of unrestrained growth; and 1996-2004, a period of no net change. During the period of unrestrained growth, females had a mean life expectancy of 46 years and maximum longevity was on the order of 80 years. Females typically gave birth to their first viable calf at 14.1 years of age (SE=0.050; range 10-21 years) and those that survived produced a total of 4.7 calves at mean intervals of 4.9 years (SE=0.18; range 2-11 years) over a reproductive lifespan typically lasting about 24 years. Older females exhibited reproductive senescence, with about 50% being post-reproductive by 38 years of age, and none reproducing after 46 years of age. Based on development of the dorsal fin - a secondary sexual characteristic - males typically attained sexual maturity at 13.0 years of age (SE=0.046; range 9-18 years) and the fin continued to develop for an average of 5.5 years (SE=0.113; range 3-7 years), such that males had typically attained physical maturity by 18.5 years of age. Males had a mean life expectancy of 31 years and maximum longevity was probably on the order of 60-70 years. Mortality curves were U-shaped for both sexes, indicating most mortality occurred early and late in life, but the right limb was steeper for males, resulting in a sex ratio that was progressively skewed toward females with increasing age (1:1 at age 15, 2:1 by age 34, and 3:1 by age 41 years). A sex- and age-structured model incorporating these parameters predicted that a population would increase at a rate of 2.4% per annum and be comprised of 46% juveniles, 22% reproductive females, 10% post-reproductive females, and 22% adult males. During 1973-96, the study population actually increased at 2.6% and was comprised, on average, of 46% juveniles, 21% reproductive females, 11% post-reproductive females and 22% adult males, indicating a good fit with the model predictions. Surprisingly, there were no major changes in reproductive parameters as the population stabilized during 1996-2004. Mean age at first birth increased slightly but significantly from 14.1 to 15.4 years (t49=3.23; P=0.002), mean age of onset of post-reproductive senescence increased from 38.4 to 40.6 years (t61=2.84; P=0.006), and calving intervals were marginally longer (5.5 versus 4.9 years; t97=2.92; P=0.091). The overall effect was a slight drop in the estimated reproductive potential of females from 4.7 to 4.5 calves. The recent decline in productivity was due almost entirely to increases in mortality, which were evident and statistically significant (7.63 X2 8.14; P 0.01) across all sex- and age-categories. Survival of viable calves to age 15 (about the age they are recruited to the adult population) dropped from 80% to 61%, and mean life expectancy declined from 46 to 30 years for females and from 31 to 19 years for males. Because the increase in mortality was broadly distributed across all sex- and age-classes, the predicted sex and age structure of the stable population remained almost unchanged at 47% juveniles, 24% reproductive females, 11% post-reproductive females, and 18% adult males. The life history parameters for neighbouring resident killer whale populations in Alaska and Washington appear to fall within the range of our unrestrained and stable models for northern BC residents, suggesting the models represent the general population biology of the resident ecotype of killer whale. We believe such models provide a useful construct for exploring and developing a better understanding of the factors that may regulate or impact killer whale populations.
Note: "Since most births occurred outside our field season, calves were generally first encountered when they were about 6 months of age. Although this makes it impossible to estimate neonate mortality from the summer survey data, we suspect mortality at birth and in the first few months of life is high. Olesiuk et al. (1990) inferred it could be as high as 37-50%, although in retrospect that is probably on the high side."
View complete PDF document (81 pages; 692K)

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Olesiuk, P.F., M.A. Bigg and G.M. Ellis (Dept. of Fisheries and Oceans, Pacific Biological Station, Nanaimo, B.C., Canada V9R 5K6) (1990). Life history and population dynamics of resident killer whales (Orcinus orca) in the coastal waters of British Columbia and Washington State. In: P.S. Hammond, S.A. Mizroch and G.P. Donovan (eds.): Individual recognition of cetaceans: Use of photo-identification and other techniques to estimate population parameters. Special Report #12, International Whaling Commission, Cambridge, p. 209-243

ABSTRACT

Life history parameters are derived for the resident form of killer whale in the coastal waters of British Columbia and Washington State based on the demographic changes observed in two communities (closed to immigration and emigration) that were monitored between 1973-4 and 1987. Females have a mean life expectancy of 50.2 years, typically give birth to their first viable calf at 14.9 years of age, produce an average of 5.35 viable calves over a 25.2 year reproductive lifespan and have a maximum longevity ofabout 80-90 years. Calving is diffusely seasonal with most births occurring in October-March. Neonate mortality is approximately 43%. The estimated proportion of mature females pregnant varies from 0.274 in April to 0.411 in September. Males have a mean life expectancy of 29.2 years, typically attain sexual maturity at 15.0 years and physical maturity at 21.0 years of age, and have a maximum longevity of about 50-60 years. Mortality curves are U-shaped for both females and males, but the curve is narrower for males. There is no evidence of density dependence in the life history parameters as a result of cropping prior to the start of the study or as the populations increased during the study.

The derived life history parameters are used to develop a sex-and age-specific matrix population model and to calculate life tables. The model accurately emulates the demographic changes observed during the study. Population projections indicate that both communities represent stable populations below their carrying capacity. These populations had a finite annual rate of increase of 2.92% and were composed of 50% juveniles, 19% mature males, 21% reproductive females and 10% post-reproductive females. Discrepancies between the sex- and age-structure of the study populations and those of a stable population can be largely attributed to the selective cropping of pods prior to the start of the study. (...)

Note: 261 Pacific Northwest killer whales were alive in 1987 in two resident communities. A community comprises individuals that share a common range and associate with one another; a pod is a group of individuals within a community that travels together the majority of the time; a subpod is a group of individuals that temporarily fragments from its pod to travel separately; an intra-pod group consists of a cohesive group of individuals within a subpod that always travels in close proximity. The genealogical trees indicate that intra-pod groups are matrilines. A matrilineal group typically comprises 2-4 generations. Pod-specific dialects suggest that related pods associate randomly. The lack of dispersal of the resident form of killer whale from their natal groups appears to be unique among mammalian social systems. This species has the potential to have developed many local races over its cosmopolitan range, with each race having unique social and behavioral characteristics.

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Olson, Paula A., Paul Ensor and Sanna Kuninga Observations of killer whales off East Antarctica, 82°-95°E, in 2009 (2012) J. CETACEAN RES. MANAGE. 12(1): 61–64, 2012

ABSTRACT

Observations of killer whales (Orcinus orca) during a survey off East Antarctica, 82°–95°E revealed previously undescribed variations in pigmentation and group associations. During the survey 24 killer whale groups were sighted south of 60°S and classified, when possible, to Types A, B, or C based on their external morphology. Sufficient observation was available for nine groups to be classified: 2 groups of Type A; 1 mixed group of Type A and Type B; 3 groups of Type C; and 3 groups with eyepatch pigmentation intermediate in size between Types B and C. These whales may represent an intergrade between Types B and C or a previously unrecognised form. One of the ‘intermediate’ groups was observed feeding in a multi-species aggregation with other cetaceans in deep water. Clearly distinguishable Type A and Type B whales were observed feeding together in a mixed aggregation, the first time that this has been documented.

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Pain, Stephanie Culture Shock New Scientist magazine (24 March, 2001)

ABSTRACT

They don't have orchestras or art galleries, tools or technology, but whales still have a rich and varied cultural life. The notion that cetaceans have any sort of culture, popular or otherwise, is hotly disputed by some. Most social scientists stubbornly resist the idea tha animals, even the great apes, have culture. After all, isn't it our languages and folklore, religion, music and all those other sophisticated strands of human culture that set us apart from the beasts? Clearly, whales and dolphins don't have art or literature; they have no architecture, agriculture or fancy cuisine. But patient observation over many years has begun to reveal behaviours that can only have been learned from other whales. And that, say whale biologists, constitutes culture.
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Parsons, K.M., Kim M. Parsons, John W. Durban, Alexander M. Burdin, Vladimir N. Burkanov, Robert L. Pitman, Jay Barlow, Lance G. Barrett-Lennard, Richard G. LeDuc, Kelly M. Robertson, Craig O. Matkin, and Paul R. Wade Geographic Patterns of Genetic Differentiation among Killer Whales in the Northern North Pacific J Hered (2013) doi: 10.1093/jhered/est037.

ABSTRACT

The difficulties associated with detecting population boundaries have long constrained the conservation and management of highly mobile, wide-ranging marine species, such as killer whales (Orcinus orca). In this study, we use data from 26 nuclear microsatellite loci and mitochondrial DNA sequences (988bp) to test a priori hypotheses about population subdivisions generated from a decade of killer whale surveys across the northern North Pacific. A total of 462 remote skin biopsies were collected from wild killer whales primarily between 2001 and 2010 from the northern Gulf of Alaska to the Sea of Okhotsk, representing both the piscivorous "resident" and the mammal-eating "transient" (or Bigg's) killer whales. Divergence of the 2 ecotypes was supported by both mtDNA and microsatellites. Geographic patterns of genetic differentiation were supported by significant regions of genetic discontinuity, providing evidence of population structuring within both ecotypes and corroborating direct observations of restricted movements of individual whales. In the Aleutian Islands (Alaska), subpopulations, or groups with significantly different mtDNA and microsatellite allele frequencies, were largely delimited by major oceanographic boundaries for resident killer whales. Although Amchitka Pass represented a major subdivision for transient killer whales between the central and western Aleutian Islands, several smaller subpopulations were evident throughout the eastern Aleutians and Bering Sea. Support for seasonally sympatric transient subpopulations around Unimak Island suggests isolating mechanisms other than geographic distance within this highly mobile top predator. Full paper HERE.
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Parsons, K.M., K.C. Balcomb III, J.K.B. Ford, and J.W. Durban The social dynamics of southern resident killer whales and conservation implications for this endangered population Animal Behaviour, Volume 77, Issue 4, April 2009, Pages 963-971.

EXCERPT

Quantitatively characterizing the social structure of a population provides important insight into the forces shaping key population processes. Moreover, long-term social dynamics provide an avenue for understanding population-level responses to changes in socioecological conditions. This is particularly true for species that show natal philopatry and highly stable hierarchically structured social units, such as the piscivorous resident killer whales of the northeast Pacific. The southern resident killer whale population is a small, demographically closed population, comprising three commonly recognized pods (J, K and L pods), that has recently been listed as endangered throughout its range in both Canadian and U.S.A. waters. In this study, we quantitatively assessed social structure in this population from 29 years of photo-identification data to characterize significant temporal changes in sociality. Preferential affiliation among killer whales within both genealogical matrilines and pods was supported by two different analytical methods and, despite interannual variability, these social clusters persisted throughout the study. All three pods experienced fluctuations in social cohesion over time, but the overall rate of intrapod affiliation was consistently lowest within L pod, the largest of the southern resident pods. The most recent increase in fluidity within social units, occurring in the mid to late 1990s, was coincident with a significant decline in population size, suggesting a possible common response to external stressors. Quantifying these trends in social structure is the first step towards understanding the causes and consequences of long-term changes in killer whale social structure.
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M. Pilot, M. E. Dahlheim & A. R. Hoelzel. Social cohesion among kin, gene flow without dispersal and the evolution of population genetic structure in the killer whale (Orcinus orca) J . EVOL. BIOL. 23 (2010) 20-31.

ABSTRACT

In social species, breeding system and gregarious behavior are key factors influencing the evolution of large-scale population genetic structure. The killer whale is a highly social apex predator showing genetic differentiation in sympatry between populations of foraging specialists (ecotypes), and low levels of genetic diversity overall. Our comparative assessments of kinship, parentage and dispersal reveal high levels of kinship within local populations and ongoing male-mediated gene flow among them, including among ecotypes that are maximally divergent within the mtDNA phylogeny. Dispersal from natal populations was rare, implying that gene flow occurs without dispersal, as a result of reproduction during temporary interactions. Discordance between nuclear and mitochondrial phylogenies was consistent with earlier studies suggesting a stochastic basis for the magnitude of mtDNA differentiation between matrilines. Taken together our results show how the killer whale breeding system, coupled with social, dispersal and foraging behaviour, contributes to the evolution of population genetic structure.
Download the paper HERE.
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Pitman, Robert L., editor, (2011) Killer Whales - The Top, Top Predator JOURNAL OF THE AMERICAN CETACEAN SOCIETY Spring 2011 Volume 40, Number 1

INTRODUCTION

Thirty-five years ago, when I first started going to sea, a quite different killer whale roamed the world’s oceans. It was a single, worldwide species and the ultimate omnivore, capable of preying upon any large vertebrate that swam into its purview, including fish, birds, mammals or reptiles. Social behavior revolved around dominant adult males, which used their much larger size and aggressive behavior to take command of harems of females and young - rather like a lion with his pride. Since that time, armadas of dedicated researchers working from small boats have spent countless thousands of hours following killer whales, studying their behavior and learning their ways. Their diligence, aided by burgeoning technologies – satellite tagging, digital photography, and genetic analyses, to name a few – has radically altered our understanding of this animal, and what has emerged is a completely different killer whale – in fact, several.

Contents

An Introduction to the World’s Premier Predator – by Robert Pitman...2
How Do We Study Killer Whales? – by John Durban and Volker Deecke...6
Killer Whales Around the World
Killer Whales of the Pacific Northwest Coast: From Pest to Paragon – by John K.B. Ford...15
Killer Whales in Alaskan Waters – by Craig Matkin and John Durban...24
North Atlantic Killer Whales – by Andy Foote...30
Crozet: Killer Whales in a Remote But Changing Environment – by Christophe Guinet and Paul Tixier...33
Centerfold: Ecotypes and Forms Drawn to Scale – by Uko Gorter...34
Antarctic Killer Whales: Top of the Food Chain at the Bottom of the World – by Robert Pitman...39
Killer Whales of California – by Alisa Schulman-Janiger, Nancy Black, and Richard Ternullo...46
Killer Whale Evolution: Populations, Ecotypes, Species, Oh My! – by Lance Barrett-Lennard...48
Predators, Prey, and Play: Killer Whales and Other Marine Mammals – by Robin W. Baird...54
Killer Whale Conservation: The Perils of Life at the Top of the Food Chain – by Lance Barrett-Lennard and Kathy Heise..58
About Our authors...63
Selected References...65
PDF of Killer Whales - The Top, Top Predator
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Pitman, Robert L., J. W. Durban, (2011) Cooperative hunting behavior, prey selectivity and prey handling by pack ice killer whales (Orcinus orca), type B, in Antarctic Peninsula waters MARINE MAMMAL SCIENCE, VOL. **, NO. **, 2011. Article first published online: 1 MAR 2011

ABSTRACT

Currently, there are three recognized ecotypes (or species) of killer whales (Orcinus orca) in Antarctic waters, including type B, a putative prey specialist on seals, which we refer to as “pack ice killer whale” (PI killer whale). During January 2009, we spent a total of 75.4 h observing three different groups of PI killer whales hunting off the western Antarctic Peninsula. Observed prey taken included 16 seals and 1 Antarctic minke whale (Balaenoptera bonaerensis). Weddell seals (Leptonychotes weddellii) were taken almost exclusively (14/15 identified seal kills), despite the fact that they represented only 15% of 365 seals identified on ice floes; thewhales entirely avoided taking crabeater seals (Lobodon carcinophaga; 82% relative abundance) and leopard seals (Hydrurga leptonyx; 3%). Of the seals killed, the whales took 12/14 (86%) off ice floes using a cooperative wave-washing behavior; they produced 120 waves during 22 separate attacks and successfully took 12/16 (75%) of the Weddell seals attacked. The mean number of waves produced per successful attack was 4.1 (range 1–10) and the mean attack duration was 30.4 min (range 15–62). Seal remains that we examined from one of the kills provided evidence of meticulous postmortem prey processing perhaps best termed "butchering."
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Pitman, Robert L., J. W. Durban, M. Greenfelder, C. Guinet, M. Jorgensen, P. A. Olson, J. Plana, P. Tixier, J. R. Towers (2010) Observations of a distinctive morphotype of killer whale (Orcinus orca), type D, from subantarctic waters Polar Biology: DOI 10.1007/s00300-010-0871-3

ABSTRACT

Studies have shown that killer whale (Orcinus orca) communities in high latitudes regularly comprise assemblages of sympatric 'ecotypes'-forms that differ in morphology, behavior, and prey preferences. Although they can appear superficially similar, recent genetic evidence suggests that breeding is assortative among ecotypes within individual communities, and species-level divergences are inferred in some cases. Here, we provide information on a recently recognized 'type D' killer whale based on photographs of a 1955 mass stranding in New Zealand and our own six at-sea sightings since 2004. It is the most distinctive-looking form of killer whale that we know of, immediately recognizable by its extremely small white eye patch. Its geographic range appears to be circumglobal in subantarctic waters between latitudes 40°S and 60°S. School sizes are relatively large (mean 17.6; range 9-35; n = 7), and although nothing is known about the type D diet, it is suspected to include fish because groups have been photographed around longline vessels where they reportedly depredate Patagonian toothfish (Dissostichus eleginoides).
PDF available from robert.pitman@noaa.gov.
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Pitman, Robert L., Wayne L. Perryman, Don Leroi, and Erik Eilers (2007) A dwarf form of killer whale in Antarctica Journal of Mammalogy, 88(1):43-48

ABSTRACT

In the early 1980s, 2 groups of Soviet scientists independently described 1, possibly 2 new dwarf species of killer whales (Orcinus) from Antarctica. We used aerial photogrammetry to determine total length (TL) of 221 individual Type C killer whales-a fish-eating ecotype that inhabits dense pack ice-in the southern Ross Sea in January 2005. We confirmed it as one of the smallest killer whales known: TL of adult females (with calves) averaged 5.2 m ± 0.23 SD (n = 33); adult males averaged 5.6 ± 0.32 m (n = 65), with the largest measuring 6.1 m. Female Type A killer whales-offshore mammal-eaters-from Soviet whaling data in the Southern Ocean were approximately 1-2 m longer, and males were 2-3 m (up to 50%) longer (maximum length 9.2 m). Killer whale communities from the North Atlantic and in waters around Japan also appear to support both a smaller, inshore, fish-eating form and a larger, offshore, mammal-eating form. We suggest that, at least in Antarctica, this degree of size dimorphism could result in reproductive isolation between sympatric ecotypes, which is consistent with hypotheses of multiple species of killer whales in the Southern Ocean. Full paper here:
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Pitman, Robert L. Good whale hunting: two tantalizing Russian reports take the author on a quest to the Antarctic, in search of two previously unrecognized kinds of killer whale Natural History, December 2003.

EXCERPT

After three seasons in Antarctica, I am convinced that in addition to the familiar killer whale from around the world, at least one and probably two additional species of killer whale lurk in the icy waters around the cold continent. What I have seen are three quite different-looking forms, which have different, but at times overlapping, ranges and habitats. The three forms also prefer different prey and travel together in herds of different size (the latter behavior suggests their social structure is probably different, too). And though there are no discernible physical barriers to prevent intermingling or interbreeding, I have never seen mixed herds or any individual that looks like an intermediate form, or hybrid. The failure to find any social mixing or apparent hybrids is highly significant in itself.
Like the earlier reports of the Soviets, these conclusions will be met with healthy skepticism by other marine-mammal scientists. To meet this challenge I have already begun some collaborative studies on the genetics, vocalizations, and morphology of Antarctic killer whales that will bring additional evidence to bear on these issues. The preliminary analysis of the tissue samples I have collected, for instance, already suggests that the three forms may not interbreed, but the results are still preliminary and verification will take a while. There are no simple answers.
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Rayne, Sierra, Michael G. Ikonomou, Peter S. Ross, Graeme M. Ellis, Lance G. Barrett-Lennard (2004) PBDEs, PBBs, and PCNs in Three Communities of Free-Ranging Killer Whales (Orcinus orca) from the Northeastern Pacific Ocean American Chemical Society

ABSTRACT

Polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), and polychlorinated naphthalenes (PCNs) were quantified in blubber biopsy samples collected from free-ranging male and female killer whales (Orcinus orca) belonging to three distinct communities (southern residents, northern residents, and transients) from the northeastern Pacific Ocean. High concentrations of PBDE were observed in male southern residents (942 ± 582 ng/g lw), male and female transients (1015 ± 605 and 885 ± 706 ng/g lw, respectively), and male and female northern residents (203 ± 116 and 415 ± 676 ng/g lw, respectively). Because of large variation within sample groups, PBDE levels generally did not differ statistically with the exception of male northern residents, which had lower PBDE concentrations than male southern residents, male transients, and female transients, perhaps reflecting the consumption of less contaminated prey items. Male transient killer whales, which consume high trophic level prey including other cetaceans and occasionally spend time near populated areas, had PBDE concentrations approximately equal to southern residents. No significant age-related relationships were observed for PBDE concentrations. PBDE concentrations were approximately 1-3 orders of magnitude greater than those of PBB (3.0-31 ng/g lw) and PCN (20-167 ng/g lw) measured in a subset of samples, suggesting that PBDEs may represent a contaminant class of concern in these marine mammals.
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Rendell, Luke, Sarah L. Mesnick, Merel L. Dalebout, Jessica Burtenshaw and Hal Whitehead (2011) Can Genetic Differences Explain Vocal Dialect Variation in Sperm Whales, Physeter macrocephalus? BEHAVIOR GENETICS DOI: 10.1007/s10519-011-9513-y

ABSTRACT

Sperm whale social groups can be assigned to vocal clans based on their production of codas, short stereotyped patterns of clicks. It is currently unclear whether genetic variation could account for these behavioural differences. We studied mitochondrial DNA (mtDNA) variation among sympatric vocal clans in the Pacific Ocean, using sequences extracted from sloughed skin samples. We sampled 194 individuals from 30 social groups belonging to one of three vocal clans. As in previous studies of sperm whales, mtDNA control region diversity was low (π = 0.003), with just 14 haplotypes present in our sample. Both hierarchical AMOVAs and partial Mantel tests showed that vocal clan was a more important factor in matrilineal population genetic structure than geography, even though our sampling spanned thousands of kilometres. The variance component attributed to vocal dialects (7.7%) was an order of magnitude higher than those previously reported in birds, while the variance component attributed to geographic area was negligible. Despite this, the two most common haplotypes were present in significant quantities in each clan, meaning that variation in the control region cannot account for behavioural variation between clans, and instead parallels the situation in humans where parent-offspring transmission of language variation has resulted in correlations with neutral genes. Our results also raise questions for the management of sperm whale populations, which has traditionally been based on dividing populations into geographic ‘stocks’, suggesting that culturally-defined vocal clans may be more appropriate management units.
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Rendell, Luke & Hal Whitehead, (2001) Culture in whales and dolphins. Behav. Brain. Sci. v24(2): 309-382

ABSTRACT

Studies of animal culture have not normally included a consideration of cetaceans. However, with several long-term field studies now maturing, this situation should change. Animal culture is generally studied by either investigating transmission mechanisms experimentally, or observing patterns of behavioural variation in wild populations which cannot be explained by either genetic or environmental factors. Taking this second, ethnographic, approach, there is good evidence for cultural transmission in several cetacean species. However, only the bottlenose dolphin (Tursiops spp.) has been shown experimentally to possess sophisticated social learning abilities, including vocal and motor imitation; other species have not been studied. There is observational evidence for imitation and teaching in killer whales. For cetaceans, and other large wide-ranging animals, excessive reliance on experimental data for evidence of culture is not productive, we favour the ethnographic approach. The complex and stable vocal and behavioural cultures of sympatric groups of killer whales (Orcinus orca) appear to have no parallel outside humans and represent an independent evolution of cultural faculties. The wide movements of cetaceans, the greater variability of the marine environment over large temporal scales relative to that on land, and the stable matrilineal social groups of some species are potentially important factors in the evolution of cetacean culture. There have been suggestions of gene-culture coevolution in cetaceans, and culture may be implicated in some unusual behavioural and life-history traits of the whales and dolphins. We hope to stimulate both discussion and research on culture in these animals.
Find the article, (with commentaries and responses) at Culture in whales and dolphins

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Riesch, Rüdiger, Lance G. Barrett-Lennard, Graeme M. Ellis, John K. B. Ford, and Volker B. Deecke (2012) Cultural traditions and the evolution of reproductive isolation: ecological speciation in killer whales? © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 1–17.

ABSTRACT
Human evolution has clearly been shaped by gene/culture interactions, and there is growing evidence that similar processes also act on populations of non-human animals. Recent theoretical studies have shown that culture can be an important evolutionary mechanism because of the ability of cultural traits to spread rapidly both vertically, obliquely, and horizontally, resulting in decreased within-group variance and increased between-group variance. Here, we collate the extensive literature on population divergence in killer whales (Orcinus orca), and argue that they are undergoing ecological speciation as a result of dietary specializations. Although we cannot exclude the possibility that cultural divergence pre-dates ecological divergence, we propose that cultural differences in the form of learned behaviours between ecologically divergent killer whale populations have resulted in sufficient reproductive isolation even in sympatry to lead to incipient speciation. Full paper HERE.

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Sentiel A. Rommel, D. Ann Pabst, William A. McLellan, James G. Mead, Charles W. Potter (1991) Anatomical evidence for a countercurrent heat exchanger associated with dolphin testes

ABSTRACT

Cetaceans possess cryptic testes that lie within the abdominal cavity, that are surrounded by primary locomotor muscles, and that are presumably exposed to core or above core body temperatures. It has remained a question as to how cetaceans produce and store viable sperm at these high temperatures. We offer anatomical evidence for a two layer arterio-venous countercurrent heat exchanger at the cetacean testis. Subcutaneous veins from the peripheral surfaces of the dorsal fin and flukes carry cool blood from the fins to the lumbo-caudal venous plexus. The lumbo-caudal venous plexus is juxtaposed to the spermatic arterial plexus, which supplies the testis. Venous plexus flow is from the ventro-lateral margins of the visceral cavity towards the vena cava. Arterial plexus flow is from the aorta towards the ventro-lateral margins of the visceral cavity and into the testis. The existence of a countercurrent heat exchanger suggests that cetaceans potentially compensate for detrimental effects of core temperatures on sperm viability and storage by regulating the temperature of blood flow to the testis.
Available On-line

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Dr. Peter S. Ross, Fisheries and Oceans Canada (2002)
Marine Ecosystem Health Program (MEHP)
Killer whales as sentinels of marine ecosystem contamination

ABSTRACT

The southern resident killer whale (Orcinus orca) population depends on the availability of prey in the shared coastal waters of Washington state and the province of British Columbia during much of the year. Declining population numbers (down 20% since 1996) have raised concerns in both Canada and the United States, leading to a threatened listing in Canada in 1999 and a recent petition to list this population under the terms of U.S. Endangered Species Act (ESA). Reports have cited diminishing prey (salmon) abundance, heavy vessel traffic and high contaminant levels. Contaminants including PCBs have been associated with adverse health effects in both humans and wildlife, including endocrine disruption, immunotoxicity and reproductive impairment. Our recent report citing northeast Pacific killer whales as among the most contaminated in the world underscores the need to better understand the source of toxic chemicals and their fate in killer whales at the top of the coastal food chain. We have initiated a two-year MEHP project (Year One: 2001; Year Two, this proposal: 2002) to evaluate the levels and patterns of Persistent Organic Pollutants (POPs; approximately 250 chemicals, including the PCBs, dioxins and pesticides) in the primary dietary component of southern resident killer whales, Chinook salmon. In Year One, we initiated a graduate student research project, set up working relationships with several laboratories, conducted preliminary experiments on stable isotopes and fatty acids, collected Chinook smolts and adults from two stocks in Puget Sound, subsampled and prepared tissues for contaminant and other analyses. Contaminant analysis is currently underway. In Year Two, we plan to complete fatty acid and stable isotope analyses, interpret data from these and contaminant analysis in the context of Chinook life history and ecology, killer whale data and food chain structure. This work will help to assess the relative importance of local vs. offshore sources of contaminants. Results will be linked to contaminant data from i) concurrent studies of Strait of Georgia fish; ii) southern resident killer whales; and iii) Puget Sound harbor seals. Results will be further interpreted using multivariate statistical evaluation of contaminant patterns and a food chain bioaccumulation model. Results will also be related to our ongoing research into the effects of POPs on the health of killer whales. This project will help to bridge Canadian and U.S. approaches to assessing contaminant levels in shared waters. Results from this research will be provided to stakeholders by way of a dedicated website and a published fact sheet. In this manner, we plan to better understand the state of contamination of the marine ecosystem in Puget Sound, the Strait of Georgia and Juan de Fuca Strait, and the risk that this contamination presents to killer whales and other high trophic level consumers.

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Ross, Peter S.; G. M. Ellis; M. G. Ikonomou; L. G. Barrett-Lennard; and R. F. Addison (2000) High PCB concentrations in free-ranging Pacific killer whales, Orcinus orca: Effect of age, sex and dietary preference Marine Pollution Bulletin 40:504-515.

ABSTRACT

Blubber biopsy samples were obtained for contaminant analysis from two discrete populations of killer whales (Orcinus orca) which frequent the coastal waters of British Columbia, Canada. Detailed life history information for the fish-eating 'resident' population, comprising two distinct communities, and the marine mammal-eating 'transient' killer whale population, provided an invaluable reference for the interpretation of contaminant concentrations. Total PCB concentrations (sum of 136 congeners detected) were surprisingly high in all three communities, but transient killer whales were particularly contanimated. PCB concentrations increaed with age in males, but were greatly reduced in reproductively active females. The absence of age, sex and inter-community differences in concentrations of polychlorinated- dibenzo-p-dioxins (PCDDs) and- dibenzofurans (PCDFs) may have partly reflected low dietary levels, but more importantly, metabolic removal of dioxin-like compounds in killer whales. While information on toxic thresholds does not exist for PCBs in cetaceans, total 2,3,7,8-TCDD Toxic Equivalent (TEQ) in most killer whales sampled easily surpassed adverse effectslevels established for harbour seals, suggesting that the majority of free-ranging killer whales in this region are at risk for toxic effects. The southern resident and transient killer whales of British Columbia can now be considered among the most contaminated cetaceans in the world.

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Salvadeo, Christian J., Daniel Lluch-Belda, Alejandro Gómez-Gallardo, Jorge Urbán-Ramírez, Colin D. MacLeod. 2010. Climate change and a poleward shift in the distribution of the Pacific white-sided dolphin in the northeastern Pacific Endang Species Res Vol. 11: 13-19, 2010.

ABSTRACT

Increasing water temperatures due to global warming mean that specific isotherms are shifting polewards. This may cause the poleward shifts in the range limits of species that are only found in specific thermal habitats. Such range shifts have been recorded in a number of plant and animal species. In the last 3 decades, we observed a decline in the presence of Pacific white-sided dolphin Lagenorhynchus obliquidens in the southwest Gulf of California (GOC), which is considered the southern boundary of their distribution. Considering that the thermal environment is physiologically important to animals, we believe that this poleward shift in the usual geographic range of the Pacific white-sided dolphin is due to long-term changes in the local climate. To obtain the conceptual framework needed to discuss such a hypothesis, we summarize and analyze current knowledge about Pacific white-sided dolphins in the southwest GOC, and sea surface temperature variability at a regional scale. Full paper HERE.

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Samarra FI, Deecke VB, Vinding K, Rasmussen MH, Swift RJ, Miller PJ. 2010. Killer whales (Orcinus orca) produce ultrasonic whistles. J Acoust Soc Am. 2010 Nov;128(5):EL205-10.

ABSTRACT

This study reports that killer whales, the largest dolphin, produce whistles with the highest fundamental frequencies ever reported in a delphinid. Using wide-band acoustic sampling from both animal-attached (Dtag) and remotely deployed hydrophone arrays, ultrasonic whistles were detected in three Northeast Atlantic populations but not in two Northeast Pacific populations. These results are inconsistent with analyses suggesting a correlation of maximum frequency of whistles with body size in delphinids, indicate substantial intraspecific variation in whistle production in killer whales, and highlight the importance of appropriate acoustic sampling techniques when conducting comparative analyses of sound repertoires.

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Saulitis, Eva, Lance Barrett-Lennard, Kathy Heise, Graeme Ellis. 2000. Foraging strategies of sympatric killer whale (Orcinus orca) populations in Prince William Sound, Alaska Marine Mammal Science 16 (1), 94-109.

ABSTRACT

Killer whales (Orcinus orca) feed on a wide variety of fish, cephalopods, and marine mammals throughout their cosmopolitan range; however, the dietary breadth that characterizes the species is not reflected in all populations. Here, we present the findings of a 14-yr study of the diet and feeding habits of killer whales in Prince William Sound, Alaska. Two non-associating forms of killer whale, termed resident and transient (Bigg et al. 1987), were identified. All prey seen taken by transients were marine mammals, including harbor seals (Phoca vitulina), Dall's porpoises (Phocoenoides dalli), Steller sea lions (Eumetopias jubatus), and harbor porpoises (Phocoena phocoena). Resident killer whales appeared to prey principally on salmon (Oncorhynchus spp.), preferring coho salmon (O. kisutch) over other, more abundant salmon species. Pacific herring (Clupea pallasi) and Pacific halibut (Hippocampus stenolepis) were also taken. Resident killer whales frequently were seen to interact in non-predatory ways with Steller sea lions and Dall's porpoises, while transients were not. Differences in the social organization and behavior of the resident and transient killer whales in Prince William Sound are discussed in the light of the dietary differences documented here.

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Scheel, D.; Craig O. Matkin and Eva Saulitis. 2001. Distribution of killer whale (Orcinus orca) pods in Prince William Sound, Alaska 1984-1996. Marine Mammal Science 17(3):555-569.

ABSTRACT

Thirteen years of encounter data (19841996) were used to examine killer whale distribution within Prince William Sound, Alaska. Four patterns of area use were found, which comprised differences between resident pods and transient groups and differences among resident groups. Resident pods frequented large open passages, while transient groups used the narrow passages and bays in the southwest. This dichotomy likely reflects reside nt use of salmon and transient use of pinniped prey resources, as well as th e different foraging strategies required for these prey types. Four resident pods (AB, AI, AJ, and AN) used Knight Island Passage more than other areas of the Sound; two (AE and AK) used all areas of the Sound more evenly. Use of the Sound by the AT1 transient whales declined in the latter part of the study. Nearshore foraging for pinniped prey by the AT1 transient whales was more common in areas where these whales spend a disproportionate amount of time, suggesting that these areas were critical foraging habitat for them.
No similar pattern emerged for Open-water Foraging for cetaceans by AT1 whales, nor for foraging by the resident whales.
Keywords: killer whale, Orcinus orca, habitat use, distribution, Alaska, Prince William Sound, foraging behavior.

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Steeman, Mette E., Martin B. Hebsgaard1, R. Ewan Fordyce, Simon Y. W. Ho, Daniel L. Rabosky, Rasmus Nielsen, Carsten Rahbek, Henrik Glenner, Martin V. Sřrensen and Eske Willerslev,Radiation of Extant Cetaceans Driven by Restructuring of the Oceans Syst Biol (2009) 58 (6): 573-585.
PRESENTATION

The remarkable fossil record of whales and dolphins (Cetacea) has made them an exemplar of macroevolution. Although their overall adaptive transition from terrestrial to fully aquatic organisms is well known, this is not true for the radiation of modern whales. Here, we explore the diversification of extant cetaceans by constructing a robust molecular phylogeny that includes 87 of 89 extant species. The phylogeny and divergence times are derived from nuclear and mitochondrial markers, calibrated with fossils. We find that the toothed whales are monophyletic, suggesting that echolocation evolved only once early in that lineage some 36–34 Ma. The rorqual family (Balaenopteridae) is restored with the exclusion of the gray whale, suggesting that gulp feeding evolved 18–16 Ma. Delphinida, comprising all living dolphins and porpoises other than the Ganges/Indus dolphins, originated about 26 Ma; it contains the taxonomically rich delphinids, which began diversifying less than 11 Ma. We tested 2 hypothesized drivers of the extant cetacean radiation by assessing the tempo of lineage accumulation through time. We find no support for a rapid burst of speciation early in the history of extant whales, contrasting with expectations of an adaptive radiation model. However, we do find support for increased diversification rates during periods of pronounced physical restructuring of the oceans. The results imply that paleogeographic and paleoceanographic changes, such as closure of major seaways, have influenced the dynamics of radiation in extant cetaceans.
"...the timing of the Mysticeti–Odontoceti divergence is estimated at 36 Ma"
FULL PAPER HERE

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Shaw, Susan D. and Kurunthachalam Kannan 2009. Polybrominated Diphenyl Ethers in Marine Ecosystems of the American Continents: Foresight from Current Knowledge. Reviews on Environmental Health 24 (2009) 157-229.

ABSTRACT

Polybrominated diphenyl ethers (PBDEs) are a class of synthetic halogenated organic compounds used in commercial and household products, such as textiles, furniture, and electronics, to increase their flame ignition resistance and to meet fire safety standards. The demonstrated persistence, bioaccumulation, and toxic potential of these compounds in animals and in humans are of increasing concern. The oceans are considered global sinks for PBDEs, as higher levels are found in marine organisms than in terrestrial biota. For the past three decades, North America has dominated the world market demand for PBDEs, consuming 95% of the penta-BDE formulation. Accordingly, the PBDE concentrations in marine biota and people from North America are the highest in the world and are increasing. Despite recent restrictions on penta- and octa-BDE commercial formulations, penta-BDE containing products will remain a reservoir for PBDE release for years to come, and the deca-BDE formulation is still in high-volume use. In this paper, we review all available data on the occurrence and trends of PBDEs in the marine ecosystems (air, water, sediments, invertebrates, fish, seabirds, and marine mammals) of North and South America. We outline here our concerns about the potential future impacts of large existing stores of banned PBDEs in consumer products, and the vast and growing reservoirs of deca-BDE as well as new and naturally occurring brominated compounds on marine ecosystems.

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Shelden, Kim E.W., Alan Baldridge, David E. Withrow (1995). Observations of Risso's dolphins Grampus griseus with gray whales, Eschrichtius robustus. Marine Mammal Science, Vol 11, No. 2, April 1995.

ABSTRACT

There are no published accounts of Risso's dolphins (Grampus griseus) interacting with gray whales (Eschrictius robustus). However, there have been numerous observations of Risso's dolphins associating with Pacirfic white-sided dolphins (Lagenorhynchus obliquidens), northern right whale dolphins (Lissodelphis borealis), pilot whales (Globicephala spp.), Dall's porpoise (Phocoenoides dalli), and on occasion sperm whales (Physeter macrocephalus) and fin whales (Balaenoptera physalus) (Hubbs 1960, Fiscus and Niggol 1965, Leatherwood et al 1983). This report describes eleven sightings of Risso's dolphins in the company of gray whales in the waters off Monterey, California, within the last 13 yr (1981-1994) (Table 1, Fig. 1).
The majority of sightings were provided by charter vessels operating in the waters off Monterey during the southbound and northbound gray whale migragion. Census records collected by the National Marine Mammal Laboratory (NMML) from shore-based stations operating during the southbound migration (1960, 1967-1981, 1984-1986, 1988, 1993-1994), and from aerial surveys flown during the census (1988, 1993-1994), were also searched for sightings. Searches of field logs maintained by other researchers conducting surveys along the California coastlline did not yield any additional sightings. Because Risso's dolphins were often not the focal animal of these surveys, it is possible that sightings may have only been gathered on an opportunistic basis or not reported at all. The increase in the number of interactions between these two species over the past few years may be explained in part by the return of the gray whale population to prewhaling size (Buckland et al. 1993) and an increase in the number of Risso's dolphins observed in the Monterey area over the last 20 yr (Leatherwood et al. 1980, Shane 1994). FULL PAPER HERE

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Simon, Malene, Peter K. McGregor and Fernando Ugarte. (2007). The relationship between the acoustic behaviour and surface activity of killer whales (Orcinus orca) that feed on herring (Clupea harengus). Acta ethologica, Volume 10, Number 2 / November, 2007.

ABSTRACT

We describe the acoustic behaviour of piscivorous killer whales in Norwegian and Icelandic waters. Whales were assigned to one of three activities (feeding, travelling or other), and sound recordings were made in their proximity with a single hydrophone and a digital audiotape (DAT) recorder. A quantitative analysis of the production of pulsed calls, whistles and echolocation clicks in the three activities revealed that there was a significant effect of activity on the production of these sound types. Both killer whales in Icelandic and Norwegian waters produced high rates of clicks and calls during feeding and low rates of click, calls and whistles during travelling. The differences can be used as acoustical markers and provides new possibilities for acoustic monitoring of killer whales in these areas. Based on the similarity between their prey choice, hunting strategies, phenotype and acoustic behaviour, we suggest that the killer whales in Icelandic and Norwegian waters belong to the same ecotype: Scandinavian herring-eating killer whales.

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Steiger, G.H., J. Calambokidis, J.M. Straley, L.M. Herman, S. Cerchio, D.R. Salden, J. Urbán-R, J.K. Jacobsen, O. von Ziegesar, K.C. Balcomb, C.M. Gabriele, M.E. Dahlheim, S. Uchida, J.K.B. Ford, P. Ladron de Guevara-P, M. Yamaguchi and J. Barlow. (2008). Geographic variation in killer whale attacks on humpback whales in the North Pacific: implications for predation pressure. Endangered Species Research 4:247-256.

ABSTRACT

We examined the incidence of rake mark scars from killer whales Orcinus orca on the flukes of humpback whales Megaptera novaeangliae throughout the North Pacific to assess geographic variation in predation pressure. We used 3650 identification photographs from 16 wintering or feeding areas collected during 1990 to 1993 to determine conservative estimates in the percentage of whales with rake mark scarring. Dramatic differences were seen in the incidence of rake marks among regions, with highest rates on wintering grounds off Mexico (26 vs. 14% at others) and feeding areas off California (20 vs. 6% at others), 2 areas between which humpback whales migrate. Although attacks are rarely witnessed, the prevalence of scars demonstrates that a substantial portion of animals are attacked, particularly those that migrate between California and Mexico. Our data also suggest that most attacks occur at or near the wintering grounds in the eastern North Pacific. The prevalence of attacks indicates that killer whale predation has the potential to be a major cause of mortality and a driving force in migratory behavior; however, the location of the attacks is inconsistent with the hypothesis that animals migrate to tropical waters to avoid predation. Our conclusion is that, at least in recent decades, attacks are made primarily on calves at the wintering grounds; this contradicts the hypothesis that killer whales historically preyed heavily on large whales in high-latitude feeding areas in the North Pacific.

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Stephanis, R. de, P. Verborgh, S. Pérez, R. Esteban, L. Minvielle-Sebastia and C. Guinet (2008). Long-term social structure of long-finned pilot whales (Globicephala melas) in the Strait of Gibraltar. Acta ethologica Volume 11, Number 2, September, 2008.

ABSTRACT

The Strait of Gibraltar is inhabited by around 216 pilot whales, which are present all year round, and nothing is known about their social structure. The aim of this study is to analyse the inter-individual association patterns within this pilot whales community to (1) provide an insight on their long-term social system and (2) to assess the relationship between sexes within this social system. Between 1999 and 2006, 23,004 km was sampled in the Strait of Gibraltar, and 4,887 images of dorsal fins of pilot whales were taken from 226 groups. The sex of 56 of the individuals could be determined genetically. The strength of the behavioural relationships between dyads of individuals was calculated, and the temporal aspects of the social structure were evaluated, showing in a non-random social structure made by constant companions. The preferred associations between individuals consisted in associations of males-females. Eight long-term units could be found with different degrees of association rates. Consequently, we propose that, in the Strait, the pilot whales exhibit a hierarchical social system composed of a population encompassing several clans of pilot whales each containing several pods. Pods will then be formed by several line units, similar to killer whale matrilineal units.

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Thewissen, J. G. M.; E. M. Williams; L. J. Roe and S. T. Hussain. (2001). Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls. Nature (London) 413(6853):277-281. 2001.

ABSTRACT

Modern members of the mammalian order Cetacea (whales, dolphins and porpoises) are obligate aquatic swimmers that are highly distinctive in morphology, lacking hair and hind limbs, and having flippers, flukes, and a streamlined body. Eocene fossils document much of cetaceans' land-to-water transition, but, until now, the most primitive representative for which a skeleton was known was clearly amphibious and lived in coastal environments. Here we report on the skeletons of two early Eocene pakicetid cetaceans, the fox-sized Ichthyolestes pinfoldi, and the wolf-sized Pakicetus attocki. Their skeletons also elucidate the relationships of cetaceans to other mammals. Morphological cladistic analyses have shown cetaceans to be most closely related to one or more mesonychians, a group of extinct, archaic ungulates, but molecular analyses have indicated that they are the sister group to hippopotamids. Our cladistic analysis indicates that cetaceans are more closely related to artiodactyls than to any mesonychian. Cetaceans are not the sister group to (any) mesonychians, nor to hippopotamids. Our analysis stops short of identifying any particular artiodactyl family as the cetacean sister group and supports monophyly of artiodactyls.

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Vester, Heike and Kurt Hammerschmidt. (2013). First record of killer whales (Orcinus orca) feeding on Atlantic salmon (Salmo salar) in northern Norway suggest a multi-prey feeding type. Marine Biodiversity Records, page 1 of 5. # Marine Biological Association of the United Kingdom, 2013, Vol. 6; e9; 2013 Published online.

ABSTRACT

Occurrence of killer whales in Norway is linked to the migration of the herring population with most sightings during wintertime. Here we describe the first record of North Atlantic killer whales feeding on Atlantic salmon inside a fjord in northern Norway during summertime, thus adding an important factor in understanding the feeding ecology of North Atlantic killer whales.


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Urian, K. W., D.A. Duffield, A. J. Read, R. S. Wells, E. D. Shell (1996). Seasonality of reproduction in bottlenose dolphins, Tursiops truncatus. Journal of Mammalogy, Vol. 77:2, p. 394-403.

Quote: Bottlenose dolphins showed diffuse peaks and considerable flexibility in their seasonality of reproduction. There was no relationship between latitude and seasonality of reproduction or synchrony of births. However, there was a correlation between origin of population and seasonality of reproduction in both wild and captive dolphins. We suggest that adaptations to local environmental conditions have the strongest influence on seasonality of reproduction in these populations of bottlenose dolphins.

Note: An alternative explanation, in keeping with more recent findings suggesting cultural influences in some species of cetaceans (see Whitehead), could be that different populations maintain different cultural traditions concerning seasonality of reproduction.

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Viricel, Amélia, Allan E. Strand, Patricia E. Rose, Vincent Ridoux and Pascale Garcia (2008). Insights on common dolphin (Delphinus delphis) social organization from genetic analysis of a mass-stranded pod. Behavioral Ecology and Sociobiology, Vol. 63, Number 2 / December, 2008

ABSTRACT

Compared to terrestrial mammals, little is known of cetacean social systems as they are generally less accessible to behavioral investigations due to their aquatic environment. The present study investigates group structure of the pelagic common dolphin, Delphinus delphis, using genetic markers. Tissue samples from 52 individuals representing a recent live mass-stranding event were compared to 42 single strandings taken from presumably different groups. The mass-stranding event occurred in 2002 on the French coast of the English Channel, whereas the single strandings were collected between 1993 and 2003 along the western coast of France (Bay of Biscay and English Channel). Analysis of mitochondrial DNA control region sequences indicated that genetic variability within the mass-stranded pod was similar to variability observed in single strandings. The mass-stranded group was composed of 41 different mitochondrial haplotypes or matrilines while the single strandings revealed 29 different haplotypes. Analysis of 11 microsatellite loci revealed that average relatedness of the mass-stranded pod was not different from average relatedness among all single strandings suggesting that individuals within the group had no closer kin relationships than animals taken from presumably different groups. These results do not support a matriarchal system and suggest that common dolphins constituting a pod are not necessarily genetically related.

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Ward, Eric J., Kim Parsons, Elizabeth E Holmes, Ken C Balcomb III and John KB Ford (2009). The role of menopause and reproductive senescence in a long-lived social mammal. Frontiers in Zoology 2009, 6:4.

ABSTRACT

Background: Menopause is a seemingly maladaptive life-history trait that is found in many longlived mammals. There are two competing evolutionary hypotheses for this phenomenon; in the adaptive view of menopause, the cessation of reproduction may increase the fitness of older females; in the non-adaptive view, menopause may be explained by physiological deterioration with age. The decline and eventual cessation of reproduction has been documented in a number of mammalian species, however the evolutionary cause of this trait is unknown.
Results: We examined a unique 30-year time series of killer whales, tracking the reproductive performance of individuals through time. Killer whales are extremely long-lived, and may have the longest documented post-reproductive lifespan of any mammal, including humans. We found no strong support for either of the adaptive hypotheses of menopause; there was little support for the presence of post-reproductive females benefitting their daughter's reproductive performance (interbirth interval and reproductive lifespan of daughters), or the number of mature recruits to the population. Oldest mothers (> 35) did appear to have a small positive impact on calf survival, suggesting that females may gain experience with age. There was mixed support for the grandmother hypothesis - grandoffspring survival probabilities were not influenced by living grandmothers, but grandmothers may positively influence survival of juveniles at a critical life stage.
Conclusion: Although existing data do not allow us to examine evolutionary tradeoffs between survival and reproduction for this species, we were able to examine the effect of maternal age on offspring survival. Our results are consistent with similar studies of other mammals - oldest mothers appear to be better mothers, producing calves with higher survival rates. Studies of juvenile survival in humans have reported positive benefits of grandmothers on newly weaned infants; our results indicate that 3-year old killer whales may experience a positive benefit from helpful grandmothers. While our research provides little support for menopause evolving to provide fitness benefits to mothers or grandmothers, our work supports previous research showing that menopause and long post-reproductive lifespans are not a human phenomenon.

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Ward, Eric J., Elizabeth E Holmes and Ken C Balcomb III (2009). Quantifying the effects of prey abundance on killer whale reproduction. Frontiers in Zoology 2009, 6:4.

ABSTRACT

Summary
1. Management decisions for threatened and endangered species require risks to be identified and prioritized, based on the degree to which they influence population dynamics. The potential for recovery of small populations at risk may be determined by multiple factors, including intrinsic population characteristics (inbreeding, sex ratios) and extrinsic variables (prey availability, disease, human disturbance). Using Bayesian statistical methods, the impact of each of these risk factors on demographic rates can be quantified and assigned probabilities to express uncertainty.
2. We assessed the impact of a wide range of factors on the fecundity of two threatened populations of killer whales Orcinus orca, specifically whether killer whale production is limited by availability of Chinook salmon Oncorhynchus tshawytscha. Additional variables included anthropogenic factors, climate variables, temporal effects, and population variables (population size, number of males, female age).
3. Our results indicate that killer whale fecundity is highly correlated with the abundance of Chinook salmon. For example, the probability of a female calving differed by 50% between years of low salmon abundance and high salmon abundance. Weak evidence exists for linking fecundity to other variables, such as sea surface temperature.
4. There was strong data support for reproductive senescence in female killer whales. This pattern of rapid maturity and gradual decline of fecundity with age commonly seen in terrestrial mammals has been documented in few marine mammal species. Maximum production for this species occurs between ages 20-22, and reproductive performance declines gradually to menopause over a period of 25 years.
5. Synthesis and applications. Our results provide strong evidence for reproductive senescence in killer whales, and more importantly, that killer whale fecundity is strongly tied to the abundance of Chinook salmon, a species that is susceptible to environmental variation and has high commercial value to fisheries. This strong predator-prey relationship highlights the importance of understanding which salmon populations overlap with killer whales seasonally and spatially, so that those salmon populations important as prey for killer whales can be identified and targeted for conservation efforts. Full paper HERE.

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Whitehead, Hal, Mary Dillon, Susan Dufault, Linda Weilgart & Jonathan Wright. (1998). Non-geographically based population structure of South Pacific sperm whales: dialects, fluke-markings and genetics. Journal of Animal Ecology 67 253-262.

ABSTRACT

1. This study addresses the issue of structure in sperm whale (Physeter macrocephalus Linnaeus) populations and whether it is geographically based.
2. During a survey around the South Pacific Ocean, we collected sloughed skin for genetic analyses, recorded coda vocalizations, and photographed fluke markings.
3. Groups of female and immature sperm whales had characteristic mitochondrial haplotypes, coda repertoires, and fluke-mark patterns, but there was no clear geographical structure in any of these attributes.
4. However, similarities of coda repertoire and mitochondrial haplotype distribution were significantly correlated among pairs of groups in a manner that was not geographically based. There was also a significant canonical correlation coefficient between coda repertoire and fluke-mark patterns.
5. These results suggest that attributes (such as vocal repertoire and techniques of predator defence) which are acquired matrilineally, and probably culturally, are conserved during the fission and dispersal of groups.

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Whitehead, H., Luke Rendell, Richard W. Osborne, Bernd Würsig (2004). Culture and conservation of non-humans with reference to whales and dolphins: review and new directions. Biological Conservation Vol. 120, No. 3, December 2004, Pages 427-437

ABSTRACT

There is increasing evidence that culture is an important determinant of behavior in some non-human species including great apes and cetaceans (whales and dolphins). In some cases, there may be repercussions for population biology and conservation. Rapidly evolving "horizontal" cultures, transmitted largely within generations, may help animals deal with anthropogenic change and even allow them to exploit it, sometimes with negative consequences for both the animals and humans. In contrast, stable "vertical" or "oblique" cultures, transmitted principally between generations, may impede adaptation to environmental change, and confound range recovery, reintroductions and translocations. Conformist stable cultures can lead to maladaptive behavior, which may be mistaken for the results of anthropogenic threats. They can also structure populations into sympatric sub-populations with distinctive cultural variants. Such structuring is common among cetaceans, among which sympatric sub-populations may face different anthropogenic threats or respond to the same threat in different ways. We suggest that non-human culture should be integrated into conservation biology when considering populations with such attributes, and also more generally by refining definitions of evolutionarily significant units and considering how cultural attributes may change our perspectives of non-humans.

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Whitehead, H.(Dalhousie Univ., Halifax Nova Scotia) (1998). Cultural Selection and Genetic Diversity in Matrilineal Whales. Science, Vol. 282, p. 1708-1711.

ABSTRACT

Low diversities of mitochondrial DNA (mtDNA) have recently been found in four species of matrilineal whale [Sperm whales, orcas, long-finned pilot whales and short-finned pilot whales]. No satisfactory explanation for this apparent anomaly has been previously suggested. Culture seems to be an important part of the lives of matrilineal whales. The selection of matrilineally transmitted cultural traits, upon which neutral mtDNA alleles "hitchhike," has the potential to strongly reduce genetic variation. Thus, in contrast to other nonhuman mammals, culture may be an important evolutionary force for the matrilineal whales.

From accompanying article: "...suggests that in sperm whales and some other species, cultural traits-learned behaviors passed on to family members-are affecting the course of genetic evolution, a situation thus far documented only in humans."

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Williams, Rob, Martin Krkošek, Erin Ashe, Trevor A. Branch, Steve Clark, Philip S. Hammond, Erich Hoyt, Dawn P. Noren, David Rosen, Arliss Winship1. (2011). Competing Conservation Objectives for Predators and Prey: Estimating Killer Whale Prey Requirements for Chinook Salmon. PLoS ONE 6(11): e26738. doi:10.1371/journal.pone.0026738.

ABSTRACT

Ecosystem-based management (EBM) of marine resources attempts to conserve interacting species. In contrast to single-species fisheries management, EBM aims to identify and resolve conflicting objectives for different species. Such a conflict may be emerging in the northeastern Pacific for southern resident killer whales (Orcinus orca) and their primary prey, Chinook salmon (Oncorhynchus tshawytscha). Both species have at-risk conservation status and transboundary (Canada–US) ranges. We modeled individual killer whale prey requirements from feeding and growth records of captive killer whales and morphometric data from historic live-capture fishery and whaling records worldwide. The models, combined with caloric value of salmon, and demographic and diet data for wild killer whales, allow us to predict salmon quantities needed to maintain and recover this killer whale population, which numbered 87 individuals in 2009. Our analyses provide new information on cost of lactation and new parameter estimates for other killer whale populations globally. Prey requirements of southern resident killer whales are difficult to reconcile with fisheries and conservation objectives for Chinook salmon, because the number of fish required is large relative to annual returns and fishery catches. For instance, a U.S. recovery goal (2.3% annual population growth of killer whales over 28 years) implies a 75% increase in energetic requirements. Reducing salmon fisheries may serve as a temporary mitigation measure to allow time for management actions to improve salmon productivity to take effect. As ecosystem-based fishery management becomes more prevalent, trade-offs between conservation objectives for predators and prey will become increasingly necessary. Our approach offers scenarios to compare relative influence of various sources of uncertainty on the resulting consumption estimates to prioritise future research efforts, and a general approach for assessing the extent of conflict between conservation objectives for threatened or protected wildlife where the interaction between affected species can be quantified.
Full paper HERE.

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Williams, Rob, Andrew W. Trites, and David E. Bain. (2002). Behavioural responses of killer whales (Orcinus orca) to whale-watching boats: opportunistic observations and experimental approaches. Journal of Zoology, 256: 255-270.

ABSTRACT

Johnstone Strait provides important summer habitat for the northern resident killer whales Orcinus orca of British Columbia. The site is also an active whale-watching area. A voluntary code of conduct requests that boats do not approach whales closer than 100 m to address perceived, rather than demonstrated, effects of boat traffic on killer whales. The purpose of the study was to test the relevance of this distance guideline. Relationships between boat traffic and whale behaviour were studied in 1995 and 1996 by shore-based theodolite tracking of 25 identifiable focal animals from the population of 209 whales. Individual killer whales were repeatedly tracked in the absence of boats and during approaches by a 5.2 m motorboat that paralleled each whale at 100 m. In addition, whales were tracked opportunistically, when no effort was made to manipulate boat traffic. Dive times, swim speeds, and surface-active behaviours such as breaching and spy-hopping were recorded. On average, male killer whales swam significantly faster than females. Whales responded to experimental approaches by adopting a less predictable path than observed during the preceding, no-boat period, although males and females used subtly different avoidance tactics. Females responded by swimming faster and increasing the angle between successive dives, whereas males maintained their speed and chose a smooth, but less direct, path. Canonical correlations between whale behaviour and vessel proximity are consistent with these conclusions, which suggest that weakening whale-watching guidelines, or not enforcing them, would result in higher levels of disturbance. High variability in whale behaviour underscores the importance of large sample size and extensive experimentation when assessing the impacts of human activity on killer whales.

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Yurk, Harald. (2001). Parallel cultural and genetic lineages in Alaskan resident type killer whales. Marine Mammal Research Unit, Department of Zoology, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.

ABSTRACT

We present evidence that at least two acoustically and genetically distinct clans (vocally related pods) of resident killer whales inhabit Prince William Sound, Alaska. We compared the sound contours of approximately 9000 calls from 480 recording sessions of six photo identified killer whale pods. The pods fell into two acoustically distinct clans, with no evidence of sharing of call types between them. One clan referred to as AB-clan, included AB AI and AN pods. The second clan, AE-clan, included AD, AE and AK pods. We identified a mean number of 12 distinct call types for each pod, based predominantly on pulsed tone components. Call types and their variants were shared among member pods of the same clan. A dendogram based on a quantitative index of acoustical similarity shows that within AB-clan, AB, AI and AN pods are vocally more similar to each other than either is to AJ pod. Within AD-clan, AD, AE and AK pods are equally similar. Using DNA from biopsy samples, we sequenced the entire mitochondrial region control region of 16 AB-clan and 12 AE-clan individuals, including members of each pod. Each clan was monomorphic for a single haplotype and the two clans differed by one transition. It thus appears that the acoustic differences between the clans, which we presume to be cultural, are distinct clans (vocally related pods) of resident killer whales inhabiting Prince William Sound, Alaska.

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Zerbini, Alexandre N., Janice M. Waite, John W. Durban, Rick LeDuc, Marilyn E. Dahlheim and Paul R. Wade. (2006). Estimating abundance of killer whales in the nearshore waters of the Gulf of Alaska and Aleutian Islands using line-transect sampling. Marine Biology: 9 August 2006.

ABSTRACT

Killer whale (/Orcinus orca/ Linnaeus, 1758) abundance in the North Pacific is known only for a few populations for which extensive longitudinal data are available, with little quantitative data from more remote regions. Line-transect ship surveys were conducted in July and August of 2001 - 2003 in coastal waters of the western Gulf of Alaska and the Aleutian Islands. Conventional and Multiple Covariate Distance Sampling methods were used to estimate the abundance of different killer whale ecotypes, which were distinguished based upon morphological and genetic data. Abundance was calculated separately for two data sets that differed in the method by which killer whale group size data were obtained. Initial group size (IGS) data corresponded to estimates of group size at the time of first sighting, and post-encounter group size (PEGS) corresponded to estimates made after closely approaching sighted groups. 'Resident'-type (fish-eating) killer whales were more abundant than the 'transient'-type (mammal-eating). Abundance estimates of resident killer whales (991 [95% CI = 379-2,585] [IGS] and 1,587 [95% CI = 608-4,140] [PEGS]), were at least four times greater than those of the transient killer whales (200 [95% CI = 81-488] [IGS] and 251 [95% CI = 97-644] whales [PEGS]). The IGS estimate of abundance is preferred for resident killer whales because the estimate based on PEGS data may show an upward bias. The PEGS estimate of abundance is likely more accurate for transients. Residents were most abundant near Kodiak Island in the northern Gulf of Alaska, around Umnak and Unalaska Islands in the eastern Aleutians, and in Seguam Pass in the central Aleutians. This ecotype was not observed between 156 and 164°W, south of the Alaska Peninsula. In contrast, transient killer whale sightings were found at higher densities south of the Alaska Peninsula between the Shumagin Islands and the eastern Aleutians. Only two sightings of 'offshore'-type killer whales were recorded during the surveys, one northeast of Unalaska Island and the other south of Kodiak Island. These are the first estimates of abundance of killer whale ecotypes in the Aleutian Islands and Alaska Peninsula area and provide a baseline for quantifying the role of these top predators in their ecosystem.

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