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This study provides the first description of the feeding aggregation recently formed by humpback whales in the Senyavin Strait, off eastern Chukotka. A total of 143 individuals were identified during the two summer and fall seasons of 2017 and 2018. More than half of the whales recorded in the first year were encountered again in the following year. The spatial distribution of feeding whales varied substantially between years, which may be explained by a shift in prey use. The structure of the feeding aggregation remained relatively stable, with a slightly higher number of new animals observed in the 2018 season. The estimated size of the aggregation was from 84 (±1.5) to 90 (±6.4) individuals in 2017 and from 105 (±3.7) to 109 (±6.2) individuals in 2018. A comparison of the whale photographs we took with the catalogues from other feeding grounds yielded matches with individuals recorded from the Chukchi Sea, Gulf of Anadyr, and waters off the Commander Islands and the eastern Aleutian Islands. Among the breeding grounds, matches were found only with catalogues of images collected from the waters off the Hawaiian Islands. Thus, we hypothesize that the feeding aggregation in the Senyavin Strait is relatively stable between seasons and within one season. There is some exchange of individuals with some other feeding grounds. This aggregation is formed mainly by whales of the Hawaiian subpopulation.

Important marine mammal areas (IMMAs)—‘discrete habitat areas, important for one or more marine mammal species, that have the potential to be delineated and managed for conservation’ (IUCN Marine Mammal Protected Areas Task Force 2018, p. 3)—were introduced in 2014 by the IUCN Marine Mammal Protected Areas Task Force to support marine mammal and wider ocean conservation. IMMAs provide decision-makers with a user-friendly, actionable tool to inform them of the whereabouts of habitat important for marine mammal survival. However, in view of their non-prescriptive, evidence-based and biocentric nature, the conservation effectiveness of IMMAs is strictly dependent on politicians’ willingness to make use of them. It has been the customary task of advocacy non-governmental organisations to lobby decision-makers to stimulate respect for environmental law, but the scientific community is increasingly joining this effort. Scientists can effectively strengthen a healthy relationship between scientific objectivity and political advocacy without damaging the credibility of conservation science. Thus, those undertaking the identification of IMMAs can be among those responsible for strongly advocating the implementation of IMMAs and other conservation initiatives.

Until recently, it has been believed that only one cetacean species of the genus Berardius, the Baird’s beaked whale (Berardius bairdii Stejneger, 1883), inhabits the northern Pacific Ocean. However, a genetic analysis of tissue samples and morphometric data provide convincing evidence for the existence of a previously undescribed Berardius species sympatric to Baird’s beaked whale, which is referred to as “black” beaked whale. The high probability of occurrence of the black beaked whale in Russian waters is established and its possible range is described in the present study. A genetic analysis of the mitochondrial DNA control region was carried out for 28 new specimens of the genus Berardius from four Far Eastern regions. According to the results, all specimens from the Commander Islands and Kamchatka Gulf belonged to the phylogroup of the Baird’s beaked whale. Of the two dead animals stranded on the Kunashir Island coast, one was identified as Baird’s beaked whale and the other as black beaked whale. Another two black beaked whales were found on the eastern coast of Sakhalin Island. These are the first records of the new Berardius species from the Russian territory confirmed by genetic analysis.

Addressing the challenge of protecting biodiversity in the global ocean requires a sound knowledge and understanding of the complex marine environment. Since 2008 the Global Ocean Biodiversity Initiative (GOBI) has been established as a voluntary dedicated group of marine institutions and scientists working to support conservation and protection of marine biodiversity. A focus has been work to support the Convention on Biological Diversity's Ecologically or Biologically Significant Marine Area (EBSA) process. GOBI partners have provided expert interpretation of evidence-based information and sought to compile and collate available information. An effective and coherent global network of marine protected areas must include bioregional representative replicates of features; once described, EBSAs can help focus attention on where and what kind of protective measures may be needed. GOBI is currently undertaking a 5-year programme of research funded by the German International Climate Initiative, working to strengthen baselines and contribute new data to the EBSA and other processes. This involves developing detailed biogeographies for the Pacific and Indian Oceans, assessing the movement of migratory species, advancing understanding of biodiversity at vents and seeps, developing a model governance system for the Costa Rica Thermal Dome, and incorporating Important Bird and Biodiversity Areas and Important Marine Mammal Areas. GOBI has taken initiatives to build on the results of the Census of Marine Life and ensure best available marine biodiversity information is considered by states and intergovernmental organizations. GOBI support for ocean governance, including data development and expert consultation, will also contribute to the United Nations Decade of Ocean Science for Sustainable Development (2021–2030). Future challenges include capacity building and new approaches to incorporate traditional knowledge.

Dietary specialization has led to the origin of several ecotypes of killer whales (Orcinus orca). Comparing the feeding habits of different populations within an ecotype is valuable for understanding the evolution of foraging strategies. In this study we investigated the diet of fish-eating killer whales in the Northwest Pacific Ocean (Avacha Gulf, Kamchatka) and compared it to the published data on Northeast Pacific fish-eating killer whales. We collected prey fragments (N = 141) after hunting events in the summer seasons of 2011–2016 and determined the species of prey. Killer whales fed mainly on various species of Pacific salmon in Avacha Gulf. Coho salmon (Oncorhynchus kisutch) (56% of samples) and chum salmon (O. keta) (31% of samples) predominated in the diet. The results are comparable to the peculiarities of the fish-eating killer whale diet in the Northeast Pacific where killer whales prefer Chinook salmon (O. tshawytscha) most of the summer but shift toward coho and chum in late summer. Avacha Gulf could be an area where killer whales come to hunt coho similar to Prince William Sound in Alaska where killer whales prefer coho to other salmon species. We found significant differences in the diet between sex-age categories. Females (N = 42) and juveniles (N = 15) were more selective and hunted mainly coho while males (N = 53) hunted chum equally to coho. Like Chinook in British Columbia, coho in Kamchatka has a prolonged spawning period. Coho is the most nutritious after Chinook. Coho’s prolonged abundance and nutritional value probably make it preferable to killer whales especially females.

Top predators strongly impact the structure of ecosystems through the top-down cascading effects on prey species. Killer whales (Orcinus orca), the top predators in marine ecosystems, are increasing their presence in the Arctic following the ice cover loss. The impact of killer whales on marine ecosystems differs dramatically across ecotypes: ‘resident’ R-type killer whales feed mostly on large fish, while ‘transient’ T-type whales feed mostly on marine mammals. We analyze the differences in geographical distribution of killer whale ecotypes in the western North Pacific in order to predict the potential effects of climate change on their range and the consequential impact on Arctic ecosystems. We show that R-type whales prevail in the coastal waters of eastern Kamchatka, Commander and Kuril Islands and in the central Okhotsk Sea, while T-type whales dominate the coastal waters of Chukotka and the coastal Okhotsk Sea. The most prominent difference between these areas is depth: in the regions where R-type whales prevail, deep waters occur close to shore, while the regions dominated by T-type whales are represented by wide shallows covered with ice in winter. We propose several hypotheses to explain this large-scale segregation, including distribution of prey species and ice cover. Habitat preferences suggest that range expansion in the Arctic induced by climate change will likely involve mostly T-type killer whales and consequently increase the predation pressure on marine mammals to a greater extent than on fish stocks. This should be considered in further studies and prediction models highlighting Arctic marine ecosystems change.

Humpback whales migrate seasonally from high latitude feeding areas to lower latitude breeding areas for mating and calving. In 2004–2006, a North Pacific basin-wide study called SPLASH was conducted as an international collaboration among various groups of researchers. The Russian Far East consists of multiple high latitude feeding areas and during SPLASH, 102 whales were identified and compared to catalogs from breeding areas. Our goal in this study was to further investigate the migratory destinations of whales from the Russian Far East using a total of 1,459 photographs of whales identified from 2004 to 2014. We compared the latest Russian catalog with the SPLASH catalog from wintering areas (2004–2006) and with two additional regional catalogs from Okinawa (1989–2006) and the northern Philippines (2000–2006). We found a total of 152 matches: 106 with Asian, 35 with Hawaiian, and 11 with Mexican breeding grounds. The match rate was higher in mainland Kamchatka and consisted mostly of whales from the Asian breeding ground. In the Commander Islands, the proportion of whales from Asia was twice that of Hawaii and six times higher than Mexico. The total match rate was low, supporting the hypothesis of some undiscovered humpback whale breeding location in the North Pacific.

Many social animals have cultural traditions that may shape their societies while the social structure can in turn influence how the culture is acquired. Killer whales possess culturally transmitted dialects. The divergence of dialects was thought to occur simultaneously and consistently with the gradual fission of matrilines. In this paper we compare the social associations across matrilineal units, Bayesian phylogeny of dialects and similarity of particular syllables to test whether dialects affect social structure and whether associations or common origin define similarity of call types. We found that neither phylogeny of dialects nor similarity of syllables was correlated to associations between matrilineal units, but similarity of syllables was correlated to phylogeny of dialects for four of the six syllables analysed. The complexity and fluidity of social ties between matrilineal units and the variation in cultural transmission patterns produce a complex relationship between the social network and the socially learned vocalizations.

There have been efforts around the globe to track individuals of many marine species and assess their movements and distribution, with the putative goal of supporting their conservation and management. Determining whether, and how, tracking data have been successfully applied to address real-world conservation issues is, however, difficult. Here, we compile a broad range of case studies from diverse marine taxa to show how tracking data have helped inform conservation policy and management, including reductions in fisheries bycatch and vessel strikes, and the design and administration of marine protected areas and important habitats. Using these examples, we highlight pathways through which the past and future investment in collecting animal tracking data might be better used to achieve tangible conservation benefits.

1. Place-based conservation can be an effective tool for addressing threats to marine mammals, but this approach presents many challenges, such as the dilemma of whether to aim for protection at appropriately large scales or through networks of smaller protected areas, and how to address the socio-economic conditions of human societies whose welfare may conflict with marine mammal survival. 2. Protecting places to conserve marine mammals started about 50 years ago, when the first parks and reserves were established to protect the critical habitat of specific populations. However, the challenges of protecting habitats that cross national borders and span oceans including the high seas remain problematic. International cooperation is needed, e. g. within the framework of multilateral environmental agreements such as the Convention on Biological Diversity (CBD) and the Convention on Migratory Species (CMS), as well as a potential new agreement through the UN Convention on the Law of the Sea (UNCLOS). 3. Increasingly, the process of demarcating marine protected areas (MPAs) is being supported by other spatial designations, including CBD's ecological or biologically significant areas (EBSAs), the International Maritime Organization's particularly sensitive sea areas (PSSAs), IUCN's key biodiversity areas (KBAs), and biologically important areas (BIAs) adopted by the USA and Australia. Recently, the important marine mammal areas (IMMA) designation has been introduced by the IUCN Task Force on marine mammal protected areas. Such approaches have the potential to increase the protection of marine mammals within the overarching approach of systematic marine spatial planning. 4. Considering the attributes of marine mammals as sentinel, umbrella and flagship species, it is likely that emerging place-based approaches that incorporate IMMAs will not only benefit marine mammal populations, but also contribute more generally to the conservation of marine and aquatic species and ecosystems.

This study was funded by the Russian Fund for the Fundamental Research (grant No. 18-04-00462). Call classifications by human observers are often subjective yet they are critical to studies of animal communication, because only the categories that are relevant for the animals themselves actually make sense in terms of correlation to the context. In this paper we test whether independent observers can correctly detect differences and similarities in killer whale repertoires. We used repertoires with different a priori levels of similarity: from different ecotypes, from different oceans, from different populations within the same ocean, and from different local subpopulations of the same population. Calls from nine killer whale populations/subpopulations were pooled into a joint sample set, and eight independent observers were asked to classify the calls into separate categories. None of the observers’ classifications strongly followed the known phylogeny of the analyzed repertoires. However, some phylogenetic relationships were reflected in the classifications substantially better than others. Most observers correctly separated the calls from two North Pacific ecotypes. Call classifications averaged across multiple observers reflected the known repertoire phylogenies better than individual classifications, and revealed the similarity of repertoires at the level of subpopulations within the same population, or closely related populations. Postprint

International audience; Mitochondrial DNA (mtDNA) differences between humpback whales on different feeding groundscan reflect the cultural transmission of migration destinations over generations, and thereforerepresent one of the very few cases of gene-culture coevolution identified in the animal kingdom.In Russian Pacific waters, photo-identification (photo-ID) studies have shown minimal interchangebetween whales feeding off the Commander Islands and those feeding in the Karaginsky Gulf,regions that are separated by only 500 km and have previously been lumped together as a singleRussian feeding ground. Here, we assessed whether genetic differentiation exists between these2 groups of humpback whales. We discovered a strong mtDNA differentiation between the 2feeding sites (FST = 0.18, ΦST = 0.14, P < 0.001). In contrast, nuclear DNA (nuDNA) polymorphisms,determined at 8 microsatellite loci, did not reveal any differentiation. Comparing our mtDNA resultswith those from a previous ocean-basin study reinforced the differences between the 2 feedingsites. Humpback whales from the Commanders appeared most similar to those of the westernGulf of Alaska and the Aleutian feeding grounds, whereas Karaginsky differed from all other NorthPacific feeding grounds. Comparison to breeding grounds suggests mixed origins for the 2 feedingsites; there are likely connections between Karaginsky and the Philippines and to a lesser extentto Okinawa, Japan, whereas the Commanders are linked to the Mexican breeding grounds. ThemtDNA differentiation between the Commander Islands and Karaginsky Gulf suggests a case ofgene-culture coevolution, correlated to fidelity to a specific feeding site within a particular feedingground. From a conservation perspective, our findings emphasize the importance of consideringthese 2 feeding sites as separate management units.

In the North Pacific, fish-eating R-type "resident" and mammal-eating T-type "transient" killer whales do not interbreed and differ in ecology and behavior. Full-length mitochondrial genomes (about 16.4 kbp) were sequenced and assembled for 12 R-type and 14 T-type killer whale samples from different areas of the western North Pacific. All R-type individuals had the same haplotype, previously described for R-type killer whales from both eastern and western North Pacific. However, haplotype diversity of R-type killer whales was much lower in the western North Pacific than in the Aleutian Islands and the eastern North Pacific. T-type whales had 3 different haplotypes, including one previously undescribed. Haplotype diversity of T-type killer whales in the Okhotsk Sea was also much lower than in the Aleutian Islands and the eastern North Pacific. The highest haplotype diversity for both R- and T-type killer whales was observed in the Aleutian Islands. We discuss how the environmental conditions during the last glacial period might have shaped the history of killer whale populations in the North Pacific. Our results suggest the recent colonization or re-colonization of the western North Pacific by small groups of killer whales originating from the central or eastern North Pacific, possibly due to favorable environmental changes after the Last Glacial Maximum.

The social structure of Baird's beaked whales is completely unstudied, and it is unknown if either females or males form long-term social associations or occur in stable groups. In this paper we summarize our observations of individually identified animals over the span of 6 yr to provide insight on their long-term social structure. We have identified 122 whales, with 28 of them encountered three times or more and thus included in the analysis of social structure. We found that the whales exhibited nonrandom patterns of social associations with some individuals preferentially associating with each other. Whales with more scarred skin had higher maximum association coefficients, which indicates that older animals and/or males were more inclined to form stable associations. Cluster analysis with a modularity test for gregariousness divided the whales into four clusters. Whales from the same clusters did not always occur together, but some individuals retained stable associations over several years. The strength of social relationships decayed over periods of months, with between-year relationships showing little deviation from what would be expected if association was random. Generally these findings do not correspond to a stable society with fixed groups but instead suggest a fission-fusion society with some stable alliances.

This paper explores how criteria to identify important marine mammal areas (IMMAs) could be developed, and nested in existing global criteria. This process would consider 134 species of marine mammals. Particular attention is given to two suites of global criteria to identify areas important for the persistence of marine biodiversity: Ecologically or Biologically Significant Areas (EBSAs) developed through the Convention on Biological Diversity (CBD), and Key Biodiversity Areas (KBAs) in revision through the International Union for the Conservation of Nature (IUCN). They are seen as mutually complementary in the development of IMMAs. The specificities necessary for identifying important areas at scales below the global level may vary according to the region, the biophysical requirements of distinct populations, and available data. Refining and testing the applicability of these global criteria on marine mammals at both regional and national scales will be necessary. Combining area-based measures with non-spatial management actions will likely be the optimal approach for ensuring marine mammal persistence given their highly migratory nature and widespread life-history stages. Capacity to enact IMMAs is strengthened by the existence of professional marine mammal associations and networks, and the recently formed IUCN Marine Mammal Protected Areas Task Force (MMPATF). The MMPATF is planning further development of IMMA criteria through joint work with the International Committee on Marine Mammal Protected Areas (ICMMPA). Copyright © 2014 John Wiley & Sons, Ltd.

Migratory marine species (MMS) include many of the world's most charismatic organisms such as marine mammals, seabirds, turtles, sharks, and tuna. Many are now among the most threatened due to the diverse range of pressures they encounter during their extensive movements. This paper shows that 21% of MMS are classified as threatened (i.e. categorized as Critically Endangered, Endangered or Vulnerable). Sea turtles are the most threatened group (85%), followed by seabirds (27%), cartilaginous fish (26%), marine mammals (15%) and bony fish (11%). Taken together 48% of MMS are threatened, Near Threatened or Data Deficient. As well as being threatened they share in common being wide-ranging animals, travelling through the waters of multiple nations as well as in Areas Beyond National Jurisdiction (ABNJ) during different times of the year. This makes their conservation a challenge, requiring coordinated action by many nations, international organizations, Multilateral Environmental Agreements (MEAs) and other stakeholders if their populations are to recover to healthy levels and be safeguarded into the future. Even though they are wide-ranging, long-term studies reveal considerable site fidelity and well-defined habitats for many species and areas. These sites are prime candidates for enhanced management such as via Marine Protect Area (MPA) designations. However, existing management frameworks do not yet contribute sufficiently to MMS conservation, MPA networks need to be expanded to capture key areas, in many cases through the application of new dynamic management techniques such as time area closures. Data on the distribution, abundance, behaviours and threats faced by many MMS are now available. These data should be used to inform the design of effective management regimes, such as MPAs, both within and beyond national jurisdictions. MEAs should ensure a full complement of MMS are included within species listings, and encourage further action to safeguard their populations. Copyright © 2014 John Wiley & Sons, Ltd.

Data collection was supported by a variety of organizations, including the Russian Fund for the Fundamental Research (Grant No. 15-04-05540), the Rufford Small Grants Fund, Whale and Dolphin Conservation, the Fundação para a Ciência e a Tecnologia (Grant No. SFRH/BD/30303/2006), Russell Trust Award of the University of St. Andrews, the Office of Naval Research, the Icelandic Research Fund (i. Rannsóknasjóður), the National Geographic Society Science and Exploration Europe (Grant No. GEFNE65-12), Vancouver Aquarium Marine Science Centre, the Canadian Ministry of Fisheries and Oceans, and the North Gulf Oceanic Society. Odontocete sounds are produced by two pairs of phonic lips situated in soft nares below the blowhole; the right pair is larger and is more likely to produce clicks, while the left pair is more likely to produce whistles. This has important implications for the cultural evolution of delphinid sounds: the greater the physical constraints, the greater the probability of random convergence. In this paper the authors examine the call structure of eight killer whale populations to identify structural constraints and to determine if they are consistent among all populations. Constraints were especially pronounced in two-voiced calls. In the calls of all eight populations, the lower component of two-voiced (biphonic) calls was typically centered below 4 kHz, while the upper component was typically above that value. The lower component of two-voiced calls had a narrower frequency range than single-voiced calls in all populations. This may be because some single-voiced calls are homologous to the lower component, while others are homologous to the higher component of two-voiced calls. Physical constraints on the call structure reduce the possible variation and increase the probability of random convergence, producing similar calls in different populations. Postprint

We investigated the influence of the type of activity and the social context on the proportion of four different structural categories of stereotyped calls in the acoustic communication of Kamchatkan killer whales. Using generalized linear models, we described the dependence of each sound category on the type of activity, the number of killer whale pods and the presence of mixed-pod groups. We found that the proportion of different sound categories depended on the number of pods and the presence of mixed-pod groups, while the type of activity did not affect the proportion of sounds of different categories. Based on the observed differences we suggest that biphonic and high-frequency monophonic calls are mainly used as family and pod markers, and help to track the position of family members at long ranges, and low-frequency monophonic calls are used as close-range intra-group signals to maintain contact between pod members in the conditions of limited underwater visibility.

The killer whale is among the few species in which cultural change accumulates over many generations, leading to cumulative cultural evolution. Killer whales have group-specific vocal repertoires which are thought to be learned rather than being genetically coded. It is supposed that divergence between vocal repertoires of sister groups increases gradually over time due to random learning mistakes and innovations. In this case, the similarity of calls across groups must be correlated with pod relatedness and, consequently, with each other. In this study we tested this prediction by comparing the patterns of call similarity between matrilines of resident killer whales from Eastern Kamchatka. We calculated the similarity of seven components from three call types across 14 matrilines. In contrast to the theoretical predictions, matrilines formed different clusters on the dendrograms made by different calls and even by different components of the same call. We suggest three possible explanations for this phenomenon. First, the lack of agreement between similarity patterns of different components may be the result of constraints in the call structure. Second, it is possible that call components change in time with different speed and/or in different directions. Third, horizontal cultural transmission of call features may occur between matrilines.

Ultrasonic whistles were previously found in North Atlantic killer whales and were suggested to occur in eastern North Pacific killer whales based on the data from autonomous recorders. In this study ultrasonic whistles were found in the recordings from two encounters with the eastern North Pacific offshore ecotype killer whales and one encounter with the western North Pacific killer whales of unknown ecotype. All ultrasonic whistles were highly stereotyped and all but two had downsweep contours. These results demonstrate that specific sound categories can be shared by killer whales from different ocean basins.

There are two recognized species in the genus Berardius, Baird’s and Arnoux’s beaked whales. In Japan, whalers have traditionally recognized two forms of Baird’s beaked whales, the common “slate-gray” form and a smaller, rare “black” form. Previous comparison of mtDNA control region sequences from three black specimens to gray specimens around Japan indicated that the two forms comprise different stocks and potentially different species. We have expanded sampling to include control region haplotypes of 178 Baird’s beaked whales from across their range in the North Pacific. We identified five additional specimens of the black form from the Aleutian Islands and Bering Sea, for a total of eight “black” specimens. The divergence between mtDNA haplotypes of the black and gray forms of Baird’s beaked whale was greater than their divergence from the congeneric Arnoux’s beaked whale found in the Southern Ocean, and similar to that observed among other congeneric beaked whale species. Taken together, genetic evidence from specimens in Japan and across the North Pacific, combined with evidence of smaller adult body size, indicate presence of an unnamed species of Berardius in the North Pacific.

Humpback whales feed on a variety of prey, but significant differences likely occur between regional feeding grounds. In this study, the diets of humpback whales were analyzed by comparing stable isotope ratios in animal tissues at three humpback whale feeding grounds in the Russian Far East: Karaginsky Gulf, Anadyr Gulf, and the Commander Islands. Anadyr Gulf is a neritic zone far from a shelf break, Karaginsky Gulf is a neritic zone close to a shelf break, and the Commander Islands represent an open oceanic ecosystem where whales feed off the shelf break. Samples

Although killer whale, Orcinus orca, dialects have been studied in detail in several populations, little attempt has been made to compare dialect characteristics between populations. In this study we investigated geographical variation in monophonic and biphonic calls among four resident populations from the North Pacific Ocean: Northern and Southern residents from British Columbia and Washington State, southern Alaska residents, and eastern Kamchatka residents. We tested predictions generated by the hypothesis that call variation across populations is the result of an accumulation of random errors and innovation by vertical cultural transmission. Call frequency contours were extracted and compared using a dynamic time-warping algorithm. We found that the diversity of monophonic calls was substantially higher than that of biphonic calls for all populations. Repertoire diversity appeared to be related to population size: in larger populations, monophonic calls were more diverse and biphonic calls less diverse. We suggest that the evolution of both monophonic and biphonic calls is caused by an interaction between stochastic processes and directional selection, but the relative effect of directional selection is greater for biphonic calls. Our analysis revealed no direct correlation between call repertoire similarity and geographical distance. Call diversity within predefined call categories, types and subtypes, showed a high degree of correspondence between populations. Our results indicate that dialect evolution is a complex process influenced by an interaction among directional selection, horizontal transmission and founder effects. We suggest several scenarios for how this might have arisen and the implications of these scenarios for call evolution and population history.

Unlike most other mammals, killer whales are capable of vocal learning and learn the dialect of their natal pod from their mothers. The classical model of killer whale dialect development suggests that the repertoire of calls is learned only “vertically” from mother to offspring, and calls evolve gradually with time by random drift caused by the accumulation of copying errors. However, some observations suggest that not only “vertical” (from mother to offspring) vocal learning can occur in killer whales, but also “horizontal” (between adult animals). In this study we analyzed the distribution of different call types and similarity of calls from the same type in different pods of killer whales from Kamchatka waters to estimate the probability of existence of interpod horizontal transmission of vocal traditions in killer whales. We found that the degree of similarity of K1 calls and K5 calls in different pods can differ. This situation contradicts the classical hypothesis and is possible in two cases: if different call types change with various speed in different pods, or if horizontal transmission of call features takes place. The distribution of K4 and K10 call types across pods also suggests the existence of horizontal transmission: K4 calls occur in the dialects of five of ten pods, and K10 calls, in six of ten pods, but only one pod has both K4 and K10 calls. Our results suggest that the real picture of the distribution of call features and call types in killer whale dialects contradicts the classical hypothesis of killer whale dialect evolution through the accumulation of copying errors.

Killer whales produce repertoires of stereotyped call types that are primarily transmitted vertically through social learning, leading to dialects between sympatric pods. The potential function of these call repertoires remains untested. In this study, we compared the reaction of Kamchatkan fish-eating killer whales to the playbacks of calls from the same and different pods. After the playback of recordings from a different pod, in three cases whales changed the direction of their movement toward the boat, and in three cases no changes in direction were observed. After the playback of recordings from the same pod (either from the same or a different unit within the pod), in seven cases whales changed the direction of their movement toward the boat, and in only one case no change in direction was observed. Whales remained silent after all six playbacks of recordings from a different pod, even when they changed direction toward the boat. After the playback of recordings from the same pod, however, in all eight cases whales started calling in response. Our playback study shows that killer whales may react to playbacks of conspecific sounds and that reactions are dependent on the type of playback stimuli.

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

Killer whale discrete calls include types containing an overlapping high-frequency component (biphonic calls) and types without an overlapping high-frequency component (monophonic calls). In the resident killer whales of the Northeast Pacific, biphonic discrete calls exhibit higher source levels than monophonic calls, which suggests different active space and consequently different functions for monophonic and biphonic call types. In this study we investigate the potential communicative functions of monophonic and biphonic discrete calls produced by killer whales from Kamchatka (Northwest Pacific). We analyze how the usage of these calls depends on the number of pods present in the area and type of activity. Our results show that the usage of monophonic and biphonic calls in Kamchatkan killer whales depends on the number of pods in the area and is less dependent on the type of activity. Biphonic calls are more common when more than one pod is present in the area and could therefore function as markers of pod and matriline affiliation, serving mainly as cohesion signals. Monophonic calls dominated the vocalizations when a single pod was present, while in the presence of more than one pod both categories were used in equal proportions.

In fish-eating North Pacific killer whales, large multi-pod aggregations of up to 100 animals often occur. These aggregations are thought to be reproductive gatherings where mating between members of different pods takes place. However, killer whales are social animals, and the role of these aggregations might also be establishing and maintaining social bonds between pods. Alternatively, it is also possible that multi-pod aggregations are in some way connected with foraging or searching for fish. In this study of killer whales in the western North Pacific, we describe multi-pod aggregations quantitatively and suggest their functional role in the life of fish-eating killer whales. We show that foraging is rare in multi-pod aggregations, whether inter-clan or intra-clan, and thus they are unlikely to play an important role in cooperative foraging. Socialising occurs more frequently in inter-clan rather than in intra-clan aggregations, which suggests the higher arousal level and possible mating during inter-clan aggregations. In summary, multi-pod aggregations of Kamchatka killer whales might be both reproductive assemblages and “clubs” of some kind in which whales gather to establish and maintain social bonds.

The problem of categorization arises in any classification system because classes should be discrete while the characteristics of most natural objects and aspects of nature are more or less gradual. In systematics, this problem usually is solved by creating several levels of categories, such as class, order, family, genus and species. In the existing killer whale discrete call classification, only two levels occur—call type and call subtype. In this paper we describe structural categories at a broader level than call type in the discrete sounds of killer whales and compare these categories between and within vocal clans in a community of resident killer whales from Southeast Kamchatka, Russian Far East, and also with killer whales outside this community. We found four main classes of discrete calls in the repertoire of resident killer whales from Southeast Kamchatka. The calls of Southeast Kamchatka transient killer whales and Sakhalin killer whales do not fall into these classes. This suggests t...

Killer whale populations may differ in genetics, morphology, ecology, and behavior. In the North Pacific, two sympatric populations (“resident” and “transient”) specialize on different prey (fish and marine mammals) and retain reproductive isolation. In the eastern North Atlantic, whales from the same populations have been observed feeding on both fish and marine mammals. Fish-eating North Pacific “residents” are more genetically related to eastern North Atlantic killer whales than to sympatric mammal-eating “transients.” In this paper, a comparison of frequency variables in killer whale calls recorded from four North Pacific resident, two North Pacific transient, and two eastern North Atlantic populations is reported to assess which factors drive the large-scale changes in call structure. Both low-frequency and high-frequency components of North Pacific transient killer whale calls have significantly lower frequencies than those of the North Pacific resident and North Atlantic populations. The difference in frequencies could be related to ecological specialization or to the phylogenetic history of these populations. North Pacific transient killer whales may have genetically inherited predisposition toward lower frequencies that may shape their learned repertoires.