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

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

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).

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).

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

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

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).

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).

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

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).

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).

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

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).

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

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).

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

Culture Shock Pain, Stephanie (2001).

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).

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

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

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

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).

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).

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

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).

Behavioural responses of killer whales (Orcinus orca) to whale-watching boats: opportunistic observations and experimental approaches Williams, 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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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.
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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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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.
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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 naïve 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, 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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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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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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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 (Orcinis 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. Full paper here.
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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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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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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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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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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 FULL PAPER, 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.
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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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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.
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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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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. 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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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., 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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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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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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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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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 & Whitehead, Hal (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, (but not commentaries or response) at BBS OnLine
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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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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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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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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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Hal Whitehead, Mary Dillon, Susan Dufault, Linda Weilgart & Jonathan Wright. (2001). Non-geographically based population structure of South Pacific sperm whales: dialects, fluke-markings and genetics.
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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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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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, 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.