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Filatova O.A.,Moscow State University | Guzeev M.A.,Saint Petersburg State University | Fedutin I.D.,Moscow State University | Burdin A.M.,Russian Academy of Sciences | Hoyt E.,Whale and Dolphin Conservation Society
Biology Bulletin | Year: 2013

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. © 2013 Pleiades Publishing, Inc.

Filatova O.A.,Moscow State University | Deecke V.B.,University of St. Andrews | Deecke V.B.,Vancouver Aquarium Marine Science Center | Ford J.K.B.,Canadian Department of Fisheries and Oceans | And 6 more authors.
Animal Behaviour | Year: 2012

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. © 2011 The Association for the Study of Animal Behaviour.

Nagaylik M.M.,Moscow State University | Filatova O.A.,Moscow State University | Ivkovich T.V.,Saint Petersburg State University | Burdin A.M.,Russian Academy of Sciences | Hoyt E.,Whale and Dolphin Conservation Society
Zoologicheskii Zhurnal | Year: 2010

The area usage by killer whales in Avacha Gulf (Kamchatka) was investigated. The activity type and GPS position with at least 5 min intervals were recorded. Photoidentification and acoustic recordings were used for the determination of pods, clans, and ecotypes. Resident groups of the Avacha clan were found to have the centre of their activities around Cape Opasnyi, at depths of less than 100 m. It is a spawning area for the Atka mackerel (Pleurogrammus monopterygius). Comparing GPS positions for the feeding events in 2005 and 2006 showed that in 2006, killer whales used a smaller area for the feeding activities; their feeding sites have shifted to the south. Killer whales from resident clan K19 were found in Avacha Gulf less frequently; they usually traveled farther from the shores; their GPS registrations were randomly distributed in the area. Transient groups were mostly recorded in the areas with depths between 50 and 100 m. The results obtained suggest the existence of inter- and intrapopulational differences in the area usage by killer whales near Kamchatka.

Williams R.,University of Washington | Williams R.,University of British Columbia | Williams R.,University of St. Andrews | Krkosek M.,University of Otago | And 9 more authors.
PLoS ONE | Year: 2011

Ecosystem-based management (EBM) of marine resources attempts to conserve interacting species. In contrast to single-species fisheries management, EBM aims to identify and resolve conflicting objectives for different species. Such a conflict may be emerging in the northeastern Pacific for southern resident killer whales (Orcinus orca) and their primary prey, Chinook salmon (Oncorhynchus tshawytscha). Both species have at-risk conservation status and transboundary (Canada-US) ranges. We modeled individual killer whale prey requirements from feeding and growth records of captive killer whales and morphometric data from historic live-capture fishery and whaling records worldwide. The models, combined with caloric value of salmon, and demographic and diet data for wild killer whales, allow us to predict salmon quantities needed to maintain and recover this killer whale population, which numbered 87 individuals in 2009. Our analyses provide new information on cost of lactation and new parameter estimates for other killer whale populations globally. Prey requirements of southern resident killer whales are difficult to reconcile with fisheries and conservation objectives for Chinook salmon, because the number of fish required is large relative to annual returns and fishery catches. For instance, a U.S. recovery goal (2.3% annual population growth of killer whales over 28 years) implies a 75% increase in energetic requirements. Reducing salmon fisheries may serve as a temporary mitigation measure to allow time for management actions to improve salmon productivity to take effect. As ecosystem-based fishery management becomes more prevalent, trade-offs between conservation objectives for predators and prey will become increasingly necessary. Our approach offers scenarios to compare relative influence of various sources of uncertainty on the resulting consumption estimates to prioritise future research efforts, and a general approach for assessing the extent of conflict between conservation objectives for threatened or protected wildlife where the interaction between affected species can be quantified. © 2011 Williams et al.

Filatova O.A.,Moscow State University | Burdin A.M.,Russian Academy of Sciences | Hoyt E.,Whale and Dolphin Conservation Society
Zoologicheskii Zhurnal | Year: 2011

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 sounds is learned only "vertically" from mother to offspring, and calls evolve gradually with time by random drift caused by 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 have 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 inter-pod horizontal transmission of vocal traditions in killer whales. We have found that similarity of Kl calls and K5 calls in different pods often don't correspond with each other. 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. Distribution of K4 and K10 call types across pods also suggests the existence of horizontal transmission: K4 calls occur in the dialects of 5 pods from 10, KlO calls - in 6 pods from 10, but only one pod has both K4 and K10 calls. Our results suggest that the real picture of call features and call types distribution in killer whale dialects contradicts the classical hypothesis of killer whale dialect evolution by accumulation of copying errors.

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