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Genome sequences can reveal the extent of inbreeding in small populations. Here, we present the first genomic characterization of type D killer whales, a distinctive eco/morphotype with a circumpolar, subantarctic distribution. Effective population size is the lowest estimated from any killer whale genome and indicates a severe population bottleneck. Consequently, type D genomes show among the highest level of inbreeding reported for any mammalian species (FROH ≥ 0.65). Detected recombination cross-over events of different haplotypes are up to an order of magnitude rarer than in other killer whale genomes studied to date. Comparison of genomic data from a museum specimen of a type D killer whale that stranded in New Zealand in 1955, with 3 modern genomes from the Cape Horn area, reveals high covariance and identity-by-state of alleles, suggesting these genomic characteristics and demographic history are shared among geographically dispersed social groups within this morphotype. Limitations to the insights gained in this study stem from the nonindependence of the 3 closely related modern genomes, the recent coalescence time of most variation within the genomes, and the nonequilibrium population history which violates the assumptions of many model-based methods. Long-range linkage disequilibrium and extensive runs of homozygosity found in type D genomes provide the potential basis for both the distinctive morphology, and the coupling of genetic barriers to gene flow with other killer whale populations.

Genome sequences can reveal the extent of inbreeding in small populations. Here, we present the first genomic characterization of type D killer whales, a distinctive eco/morphotype with a circumpolar, subantarctic distribution. Effective population size is the lowest estimated from any killer whale genome and indicates a severe population bottleneck. Consequently, type D genomes show among the highest level of inbreeding reported for any mammalian species (FROH ≥ 0.65). Detected recombination cross-over events of different haplotypes are up to an order of magnitude rarer than in other killer whale genomes studied to date. Comparison of genomic data from a museum specimen of a type D killer whale that stranded in New Zealand in 1955, with 3 modern genomes from the Cape Horn area, reveals high covariance and identity-by-state of alleles, suggesting these genomic characteristics and demographic history are shared among geographically dispersed social groups within this morphotype. Limitations to the insights gained in this study stem from the nonindependence of the 3 closely related modern genomes, the recent coalescence time of most variation within the genomes, and the nonequilibrium population history which violates the assumptions of many model-based methods. Long-range linkage disequilibrium and extensive runs of homozygosity found in type D genomes provide the potential basis for both the distinctive morphology, and the coupling of genetic barriers to gene flow with other killer whale populations.

The rescue attempts of stranded whales and euthanasia considerations must include condition assessments of the individual involved, but this is challenged by our insufficient knowledge about the health statuses of these whales. Here, we describe three separate strandings of a young male killer whale (Orcinus orca) in shallow Danish waters during 2021-2022. During the first two stranding events, the whale exhibited remarkable behavior and, after refloating attempts and several kilometers of swimming, it returned to shallow water. This suggests that it actively chose to be in this shallow water, perhaps to ensure free airways and respiration. During the last stranding, it stayed in shallow water for 30 days, during which, euthanasia was considered due to its seemingly worsened condition, including a collapsed dorsal fin. However, suddenly, the whale swam away and, a year later, he was seen alive, confirming that euthanasia would have been the wrong decision. This case raises an important question as to when and under what circumstances active human interventions, such as refloating attempts, should be launched and when euthanasia should be carried out. Every stranding is unique and decisions should be based on thorough considerations of the animal's health and the chance of a successful rescue.

Genome sequences can reveal the extent of inbreeding in small populations. Here, we present the first genomic characterization of type D killer whales, a distinctive eco/morphotype with a circumpolar, subantarctic distribution. Effective population size is the lowest estimated from any killer whale genome and indicates a severe population bottleneck. Consequently, type D genomes show among the highest level of inbreeding reported for any mammalian species (FROH ≥ 0.65). Detected recombination cross-over events of different haplotypes are up to an order of magnitude rarer than in other killer whale genomes studied to date. Comparison of genomic data from a museum specimen of a type D killer whale that stranded in New Zealand in 1955, with 3 modern genomes from the Cape Horn area, reveals high covariance and identity-by-state of alleles, suggesting these genomic characteristics and demographic history are shared among geographically dispersed social groups within this morphotype. Limitations to the insights gained in this study stem from the nonindependence of the 3 closely related modern genomes, the recent coalescence time of most variation within the genomes, and the nonequilibrium population history which violates the assumptions of many model-based methods. Long-range linkage disequilibrium and extensive runs of homozygosity found in type D genomes provide the potential basis for both the distinctive morphology, and the coupling of genetic barriers to gene flow with other killer whale populations.

[EN] The conservation of wildlife is one of the most pressing issues in the current times, but wildlife conservation economic values have often been largely ignored due to an absence of market prices, as setting an economic value on biodiversity or whole ecosystems can be challenging. Nevertheless, valuing wildlife can be of great significance to improve decision-making in the conservation field, as it can provide a complementary perspective based on economic principles. Whale-watching provides an opportunity for the economic valuation of wildlife. Specifically, it offers a framework in which the economic revenue allows the economic valuation of the targeted cetaceans to be estimated through the direct and indirect expenditure of the tourists who purchase whale-watching tours. Here, we performed an economic analysis based on population abundances of the three main species targeted by the whale-watching companies in the Strait of Gibraltar (Spain): long-finned pilot whales (Globicephala melas), common dolphins (Delphinus delphis) and killer whales (Orcinus orca). These species generated a total annual income of €4,089,056, €1,876,833, and €505,389, respectively, and each individual would generate an average of €14,048, €951, and €36,099 each year, respectively. Incorporating life expectancy, this corresponded to a total population value of €112,426,185, €16,685,147, and €19,171,107, respectively, over their lifetime. These values provide an idea of the potential contribution of cetaceans to the local economy but only represent their non-consumptive value based on tourism. Our results reinforce the idea that a sustainable, high-quality whale-watching culture, under ACCOBAMS High-Quality Whale-Watching requirements, should be promoted to ensure a sustainable industry, stable economic income and the viability of cetacean populations in the Strait of Gibraltar, [ES] La conservación de la vida salvaje es uno de los retos clave del mundo actual. Sin embargo, los valores económicos derivados de la conservación de la vida salvaje a menudo han sido pasados por alto debido a la ausencia de precios de mercado, ya que asignar un valor económico a la biodiversidad o a ecosistemas enteros puede ser complejo. No obstante, valorar la vida salvaje puede ser de gran importancia para mejorar la toma de decisiones en el campo de la conservación, ya que puede proporcionar una perspectiva complementaria basada en principios económicos. El avistamiento de cetáceos brinda una oportunidad para realizar este tipo de valoración económica. Específicamente, ofrece un marco en el cual los ingresos económicos generados permiten la evaluación y estimación del valor económico de los cetáceos objetivo basado en el gasto directo e indirecto de los turistas que realizan tours de avistamiento de cetáceos. En este estudio, realizamos un análisis económico basado en las abundancias poblacionales de las tres principales especies objetivo de las compañías de avistamiento de cetáceos en el Estrecho de Gibraltar (España): calderones comunes (Globicephala melas), delfines comunes (Delphinus delphis) y orcas (Orcinus orca). Estas especies generaron respectivamente un ingreso total anual de 4.089.056 €, 1.876.833 € y 505.389 €, donde cada individuo generaría un promedio de 14.048 €, 951 € y 36.099€ cada año. Al incorporar la esperanza de vida, esto se correspondió con un valor total de la población de 112.426.185 €, 16.685.147 € y 19.171.107 € a lo largo de su vida. Estos valores brindan una idea de la contribución potencial de los cetáceos a la economía local, pero solo representan su valor no consumitivo basado en el turismo. Nuestros resultados refuerzan la idea de que se debe promover una cultura de avistamiento de cetáceos sostenible y de alta calidad, bajo los requisitos de observación de cetáceos de alta calidad de ACCOBAMS, para garantizar una industria so

Orcinus orca (killer whale) - LACM-084249 - male - 6.65 m - Pelvic location - LA County Museum

Orcinus orca (killer whale) - BCPM-12844 - female - unknown length - Pelvic location - Royal BC Museum

Orcinus orca (killer whale) - AMNH-34276 - male - unknown length - Pelvic location - American Museum of Natural History

Runs of homozygosity (ROH) occur when offspring inherit haplotypes that are identical by descent from each parent. Length distributions of ROH are informative about population history; specifically, the probability of inbreeding mediated by mating system and/or population demography. Here, we investigated whether variation in killer whale (Orcinus orca) demographic history is reflected in genome-wide heterozygosity and ROH length distributions, using a global data set of 26 genomes representative of geographic and ecotypic variation in this species, and two F1 admixed individuals with Pacific-Atlantic parentage. We first reconstructed demographic history for each population as changes in effective population size through time using the pairwise sequential Markovian coalescent (PSMC) method. We found a subset of populations declined in effective population size during the Late Pleistocene, while others had more stable demography. Genomes inferred to have undergone ancestral declines in effective population size, were autozygous at hundreds of short ROH (<1 Mb), reflecting high background relatedness due to coalescence of haplotypes deep within the pedigree. In contrast, longer and therefore younger ROH (>1.5 Mb) were found in low latitude populations, and populations of known conservation concern. These include a Scottish killer whale, for which 37.8% of the autosomes were comprised of ROH >1.5 Mb in length. The fate of this population, in which only two adult males have been sighted in the past five years, and zero fecundity over the last two decades, may be inextricably linked to its demographic history and consequential inbreeding depression.

Runs of homozygosity (ROH) occur when offspring inherit haplotypes that are identical by descent from each parent. Length distributions of ROH are informative about population history; specifically, the probability of inbreeding mediated by mating system and/or population demography. Here, we investigated whether variation in killer whale (Orcinus orca) demographic history is reflected in genome-wide heterozygosity and ROH length distributions, using a global data set of 26 genomes representative of geographic and ecotypic variation in this species, and two F1 admixed individuals with Pacific-Atlantic parentage. We first reconstructed demographic history for each population as changes in effective population size through time using the pairwise sequential Markovian coalescent (PSMC) method. We found a subset of populations declined in effective population size during the Late Pleistocene, while others had more stable demography. Genomes inferred to have undergone ancestral declines in effective population size, were autozygous at hundreds of short ROH (<1 Mb), reflecting high background relatedness due to coalescence of haplotypes deep within the pedigree. In contrast, longer and therefore younger ROH (>1.5 Mb) were found in low latitude populations, and populations of known conservation concern. These include a Scottish killer whale, for which 37.8% of the autosomes were comprised of ROH >1.5 Mb in length. The fate of this population, in which only two adult males have been sighted in the past five years, and zero fecundity over the last two decades, may be inextricably linked to its demographic history and consequential inbreeding depression.

Echolocation click features are compared for three different killer whale ecotypes in the Northeast Pacific off the coast of Washington. A dataset consisting of manually labeled killer whale encounters identified to ecotype based on pulsed call matching was used to generate echolocation click archetypes for resident, transient and offshore killer whales. Results indicate that resident and offshore killer whales can be distinguished acoustically based on the spectral shape and inter-click intervals of their echolocation clicks. Efficient, semi-automated identification will allow expanded use of passive acoustic monitoring for management of these populations.

Echolocation click features are compared for three different killer whale ecotypes in the Northeast Pacific off the coast of Washington. A dataset consisting of manually labeled killer whale encounters identified to ecotype based on pulsed call matching was used to generate echolocation click archetypes for resident, transient and offshore killer whales. Results indicate that resident and offshore killer whales can be distinguished acoustically based on the spectral shape and inter-click intervals of their echolocation clicks. Efficient, semi-automated identification will allow expanded use of passive acoustic monitoring for management of these populations.

Runs of homozygosity (ROH) occur when offspring inherit haplotypes that are identical by descent from each parent. Length distributions of ROH are informative about population history; specifically, the probability of inbreeding mediated by mating system and/or population demography. Here, we investigated whether variation in killer whale (Orcinus orca) demographic history is reflected in genome-wide heterozygosity and ROH length distributions, using a global data set of 26 genomes representative of geographic and ecotypic variation in this species, and two F1 admixed individuals with Pacific-Atlantic parentage. We first reconstructed demographic history for each population as changes in effective population size through time using the pairwise sequential Markovian coalescent (PSMC) method. We found a subset of populations declined in effective population size during the Late Pleistocene, while others had more stable demography. Genomes inferred to have undergone ancestral declines in effective population size, were autozygous at hundreds of short ROH (<1 Mb), reflecting high background relatedness due to coalescence of haplotypes deep within the pedigree. In contrast, longer and therefore younger ROH (>1.5 Mb) were found in low latitude populations, and populations of known conservation concern. These include a Scottish killer whale, for which 37.8% of the autosomes were comprised of ROH >1.5 Mb in length. The fate of this population, in which only two adult males have been sighted in the past five years, and zero fecundity over the last two decades, may be inextricably linked to its demographic history and consequential inbreeding depression.

Runs of homozygosity (ROH) occur when offspring inherit haplotypes that are identical by descent from each parent. Length distributions of ROH are informative about population history; specifically, the probability of inbreeding mediated by mating system and/or population demography. Here, we investigated whether variation in killer whale (Orcinus orca) demographic history is reflected in genome-wide heterozygosity and ROH length distributions, using a global data set of 26 genomes representative of geographic and ecotypic variation in this species, and two F1 admixed individuals with Pacific-Atlantic parentage. We first reconstructed demographic history for each population as changes in effective population size through time using the pairwise sequential Markovian coalescent (PSMC) method. We found a subset of populations declined in effective population size during the Late Pleistocene, while others had more stable demography. Genomes inferred to have undergone ancestral declines in effective population size, were autozygous at hundreds of short ROH (<1 Mb), reflecting high background relatedness due to coalescence of haplotypes deep within the pedigree. In contrast, longer and therefore younger ROH (>1.5 Mb) were found in low latitude populations, and populations of known conservation concern. These include a Scottish killer whale, for which 37.8% of the autosomes were comprised of ROH >1.5 Mb in length. The fate of this population, in which only two adult males have been sighted in the past five years, and zero fecundity over the last two decades, may be inextricably linked to its demographic history and consequential inbreeding depression.

Jolly-Seber capture-mark-recapture models to estimate Crozet regular and type-D Killer whales populations. All codes are available for the simulation, the real data and the trends analysis (1) Simulation code (codesimul.R) is running alone. (2) Real data code (code_vraidata_revfin.R) makes use of three matrices that change depending on the ecotype: - The Capture History (CH_2106_m.csv, CH_2106_d.csv), rows correspond to individuals and columns to years. For regular killer whales this matrix contains 3 possible observations (observed from the coast, observed depredating, non observed) and 2 observations for Type-D killer whales (observed depredating, non observed) - The Marking status (Mk_2106_m.csv, Mk_2106_d.csv), rows correspond to individuals and columns to years. For both ecotype they contain three possible marking status as described in the ESM. - The maturity status (St_2106_m.csv, St_2106_d.csv), rows correspond to individuals and columns to years. For both ecotype they contain four different states (non identify, new-born, juvenile and adult). Two other matrices are the same for both ecotypes - The standardized effort (Effort_stand_boat.csv) contains the yearly effort divided by the maximum number of photographs taken during the study period. - The state matrix (z_init_cro2705.csv) is used to initiate the state matrix from the models. (3) The trend_test.R file presents the extraction of model outputs (regular killer whales: CrozetFinrevfinfin.Rdata, Type-D killer-whales: DFinrevfinfin.Rdata) and their analysis trough different linear and non linear models.

Runs of homozygosity (ROH) occur when offspring inherit haplotypes that are identical by descent from each parent. Length distributions of ROH are informative about population history; specifically, the probability of inbreeding mediated by mating system and/or population demography. Here, we investigated whether variation in killer whale (Orcinus orca) demographic history is reflected in genome-wide heterozygosity and ROH length distributions, using a global data set of 26 genomes representative of geographic and ecotypic variation in this species, and two F1 admixed individuals with Pacific-Atlantic parentage. We first reconstructed demographic history for each population as changes in effective population size through time using the pairwise sequential Markovian coalescent (PSMC) method. We found a subset of populations declined in effective population size during the Late Pleistocene, while others had more stable demography. Genomes inferred to have undergone ancestral declines in effective population size, were autozygous at hundreds of short ROH (<1 Mb), reflecting high background relatedness due to coalescence of haplotypes deep within the pedigree. In contrast, longer and therefore younger ROH (>1.5 Mb) were found in low latitude populations, and populations of known conservation concern. These include a Scottish killer whale, for which 37.8% of the autosomes were comprised of ROH >1.5 Mb in length. The fate of this population, in which only two adult males have been sighted in the past five years, and zero fecundity over the last two decades, may be inextricably linked to its demographic history and consequential inbreeding depression.

Runs of homozygosity (ROH) occur when offspring inherit haplotypes that are identical by descent from each parent. Length distributions of ROH are informative about population history; specifically, the probability of inbreeding mediated by mating system and/or population demography. Here, we investigated whether variation in killer whale (Orcinus orca) demographic history is reflected in genome-wide heterozygosity and ROH length distributions, using a global data set of 26 genomes representative of geographic and ecotypic variation in this species, and two F1 admixed individuals with Pacific-Atlantic parentage. We first reconstructed demographic history for each population as changes in effective population size through time using the pairwise sequential Markovian coalescent (PSMC) method. We found a subset of populations declined in effective population size during the Late Pleistocene, while others had more stable demography. Genomes inferred to have undergone ancestral declines in effective population size, were autozygous at hundreds of short ROH (<1 Mb), reflecting high background relatedness due to coalescence of haplotypes deep within the pedigree. In contrast, longer and therefore younger ROH (>1.5 Mb) were found in low latitude populations, and populations of known conservation concern. These include a Scottish killer whale, for which 37.8% of the autosomes were comprised of ROH >1.5 Mb in length. The fate of this population, in which only two adult males have been sighted in the past five years, and zero fecundity over the last two decades, may be inextricably linked to its demographic history and consequential inbreeding depression.

Runs of homozygosity (ROH) occur when offspring inherit haplotypes that are identical by descent from each parent. Length distributions of ROH are informative about population history; specifically, the probability of inbreeding mediated by mating system and/or population demography. Here, we investigate whether variation in killer whale (Orcinus orca) demographic history is reflected in genome-wide heterozygosity and ROH length distributions, using a global dataset of 26 genomes representative of geographic and ecotypic variation in this species, and two F1 admixed individuals with Pacific-Atlantic parentage. We first reconstruct demographic history for each population as changes in effective population size through time using the pairwise sequential Markovian coalescent (PSMC) method. We find a subset of populations declined in effective population size during the Late Pleistocene, while others had more stable demography. Genomes inferred to have undergone ancestral declines in effective population size, were autozygous at hundreds of short ROH (<1Mb), reflecting high background relatedness due to coalescence of haplotypes deep within the pedigree. In contrast, longer and therefore younger ROH (>1.5 Mb) were found in low latitude populations, and populations of known conservation concern. These include a Scottish killer whale, for which 37.8% of the autosomes were comprised of ROH >1.5 Mb in length. The fate of this population, in which only two adult males have been sighted in the past five years, and zero fecundity over the last two decades, may be inextricably linked to its demographic history and consequential inbreeding depression.

Food availability has been identified as a critical factor influencing the growth, individual health, and population dynamics of killer whales (Orcinus orca) in the coastal waters of the eastern North Pacific Ocean. Between 2014 and 2019 we conducted 113 hand-launched unmanned aerial system flights over mammal-eating Bigg’s killer whales around Vancouver Island, resulting in 20,545 aerial photographs of 95 individually identified animals. I conducted photogrammetric measurements from high-quality images in 91 individuals, a sample that ranged from first-year calves to mature adults of both sexes; this is the first study to estimate size, growth, and health of Bigg’s killer whales. Individual lengths ranged from a 2.4m neonate to an 8.3m 38-year-old male. Using a Richard’s growth curve model, I estimated asymptotic adult length at 6.4 ± 0.1m (standard error) in females and 7.3 ± 0.2m in males, as well as age of inflection at 14.2 ± 2.8 years in females and 18.4 ± 2.3 years in males. Comparison with sympatric salmon-eating Southern Resident killer whales found that both sexes of Bigg’s killer whale measured significantly longer than Southern Residents (female z-test P = 0.003; male z-test P = 0.093) but there was no significant difference in age of inflection between males (z-test, P = 0.53) or females (z-test, P = 0.45) between the two populations. Analysis of eye patch ratio (a proxy for body condition) revealed that all age/sex classes of Bigg’s killer whales were more robust than Southern Resident killer whales, and the difference was most significant when comparing calves (z-test, P < 0.0001) and juveniles (z-test, P < 0.0001) between the two populations. I propose that in the absence of major discrepancies in growth trends, morphometric divergences between the two populations are largely a function of prey availability.

Food availability has been identified as a critical factor influencing the growth, individual health, and population dynamics of killer whales (Orcinus orca) in the coastal waters of the eastern North Pacific Ocean. Between 2014 and 2019 we conducted 113 hand-launched unmanned aerial system flights over mammal-eating Bigg’s killer whales around Vancouver Island, resulting in 20,545 aerial photographs of 95 individually identified animals. I conducted photogrammetric measurements from high-quality images in 91 individuals, a sample that ranged from first-year calves to mature adults of both sexes; this is the first study to estimate size, growth, and health of Bigg’s killer whales. Individual lengths ranged from a 2.4m neonate to an 8.3m 38-year-old male. Using a Richard’s growth curve model, I estimated asymptotic adult length at 6.4 ± 0.1m (standard error) in females and 7.3 ± 0.2m in males, as well as age of inflection at 14.2 ± 2.8 years in females and 18.4 ± 2.3 years in males. Comparison with sympatric salmon-eating Southern Resident killer whales found that both sexes of Bigg’s killer whale measured significantly longer than Southern Residents (female z-test P = 0.003; male z-test P = 0.093) but there was no significant difference in age of inflection between males (z-test, P = 0.53) or females (z-test, P = 0.45) between the two populations. Analysis of eye patch ratio (a proxy for body condition) revealed that all age/sex classes of Bigg’s killer whales were more robust than Southern Resident killer whales, and the difference was most significant when comparing calves (z-test, P < 0.0001) and juveniles (z-test, P < 0.0001) between the two populations. I propose that in the absence of major discrepancies in growth trends, morphometric divergences between the two populations are largely a function of prey availability.

Killer whales produce pulsed calls, which are used for communication. Calls are highly stereotyped and repertoires are unique to individual pods. Discrimination amongst these calls and comparison of call repertoires between pods can help determine population structure in killer whales and can be used to track pod movements. Calls were detected in underwater acoustic recordings in August and September 2017 in the Arctic waters of Eclipse Sound, in Nunavut, Canada. We present a repertoire of killer whale calls recorded. Eleven stereotypic call types, three biphonic and eight monophonic, were identified using manual call organization and manual whistle contour extraction. A higher diversity of calls was detected in the hydrophone located in the known narwhal aggregation site in Milne Inlet, than at the second hydrophone deployed at the mouth of Eclipse Sound which is the proposed entrance and exit point for the killer whales. The potential for increased killer whale presence and magnitude of predation on narwhals is a source of concern for management of the population and by Inuit subsistence hunters who rely on narwhals for food and economic benefit. Describing the acoustic repertoire of killer whales seasonally present in the Canadian Arctic may help understand their behavior and seasonal movements. The results presented may provide a basis for future acoustic comparisons across the North Atlantic and aid in characterizing killer whale ecotypes making seasonal incursions into Arctic waters.

© 2019 Inter-Research. All Rights Reserved. Fisheries may generate new feeding opportunities for marine predators, which switch foraging behaviour to depredation when they feed on fish directly from fishing gear. However, the role of diet in the propensity of individuals to depredate and whether the depredated resource is artificial or part of the natural diet of individuals is often unclear. Using stable isotopes, this study investigated the importance of the commercially exploited Patagonian toothfish Dissostichus eleginoides in the diet of generalist subantarctic killer whales Orcinus orca depredating this fish at Crozet (45°S, 50°E). The isotopic niche of these killer whales was large and overlapped with that of sperm whales Physeter macrocephalus from the same region, which feed on toothfish both naturally and through depredation. There was no isotopic difference between killer whales that depredated toothfish and those that did not. Isotopic mixing models indicated that prey groups including large/medium sized toothfish and elephant seal Mirounga leonina pups represented ~60% of the diet relative to prey groups including penguins, baleen whales and coastal fish. These results indicate that toothfish are an important natural prey item of Crozet killer whales and that switching to depredation primarily occurs when fisheries facilitate access to that resource. This study suggests that toothfish, as a commercial species, may also have a key role as prey for top predators in subantarctic ecosystems. Therefore, assessing the extent to which predators use that resource naturally or from fisheries is now needed to improve both fish stock management and species conservation strategies.

Killer whales produce pulsed calls, which are used for communication. Calls are highly stereotyped and repertoires are unique to individual pods. Discrimination amongst these calls and comparison of call repertoires between pods can help determine population structure in killer whales and can be used to track pod movements. Calls were detected in underwater acoustic recordings in August and September 2017 in the Arctic waters of Eclipse Sound, in Nunavut, Canada. We present a repertoire of killer whale calls recorded. Eleven stereotypic call types, three biphonic and eight monophonic, were identified using manual call organization and manual whistle contour extraction. A higher diversity of calls was detected in the hydrophone located in the known narwhal aggregation site in Milne Inlet, than at the second hydrophone deployed at the mouth of Eclipse Sound which is the proposed entrance and exit point for the killer whales. The potential for increased killer whale presence and magnitude of predation on narwhals is a source of concern for management of the population and by Inuit subsistence hunters who rely on narwhals for food and economic benefit. Describing the acoustic repertoire of killer whales seasonally present in the Canadian Arctic may help understand their behavior and seasonal movements. The results presented may provide a basis for future acoustic comparisons across the North Atlantic and aid in characterizing killer whale ecotypes making seasonal incursions into Arctic waters.

Fisheries may generate new feeding opportunities for marine predators, which switch foraging behaviour to depredation when they feed on fish directly from fishing gear. However, the role of diet in the propensity of individuals to depredate and whether the depredated resource is artificial or part of the natural diet of individuals is often unclear. Using stable isotopes, this study investigated the importance of the commercially exploited Patagonian toothfish Dissostichus eleginoides in the diet of generalist subantarctic killer whales Orcinus orca depredating this fish at Crozet (45°S, 50°E). The isotopic niche of these killer whales was large and overlapped with that of sperm whales Physeter macrocephalus from the same region, which feed on toothfish both naturally and through depredation. There was no isotopic difference between killer whales that depredated toothfish and those that did not. Isotopic mixing models indicated that prey groups including large/medium sized toothfish and elephant seal Mirounga leonina pups represented ~60% of the diet relative to prey groups including penguins, baleen whales and coastal fish. These results indicate that toothfish are an important natural prey item of Crozet killer whales and that switching to depredation primarily occurs when fisheries facilitate access to that resource. This study suggests that toothfish, as a commercial species, may also have a key role as prey for top predators in subantarctic ecosystems. Therefore, assessing the extent to which predators use that resource naturally or from fisheries is now needed to improve both fish stock management and species conservation strategies

The effect of sound on the behaviour of sharks has not been investigated since the 1970s. Sound is, however, an important sensory stimulus underwater, as it can spread in all directions quickly and propagate further than any other sensory cue. We used a baited underwater camera rig to record the behavioural responses of eight species of sharks (seven reef and coastal shark species and the white shark, Carcharodon carcharias) to the playback of two distinct sound stimuli in the wild: an orca call sequence and an artificially generated sound. When sounds were playing, reef and coastal sharks were less numerous in the area, were responsible for fewer interactions with the baited test rigs, and displayed less ‘inquisitive’ behaviour, compared to during silent control trials. White sharks spent less time around the baited camera rig when the artificial sound was presented, but showed no significant difference in behaviour in response to orca calls. The use of the presented acoustic stimuli alone is not an effective deterrent for C. carcharias. The behavioural response of reef sharks to sound raises concern about the effects of anthropogenic noise on these taxa.

The endangered Southern Resident Killer Whale (SRKW) population is an icon of the Pacific Northeast. The population has experienced a 10 percent decline in population since 2005 and now number only 76 individuals, the lowest abundance in more than 30 years. The SRKWs have been shown to be food-limited with declines in survival and reproduction in years following low salmon availability. Diet studies conducted on the SRKWs have shown a strong prey preference for Chinook salmon (Oncorhynchus tshawytscha) in the summer, yet uncertainty remains about prey preferences and foraging behavior. To help fill this data gap, I used high-resolution aerial images to quantify and describe foraging behavior from a new perspective. Specifically, I reviewed images collected by a small unmanned hexacopter during five individual month-long field efforts between 2015 and 2017. From this collection 29 distinct foraging events were documented in 2,384 images that allowed for photogrammetry measurements of fish size, and species identification of fish preyed upon. The data show that there is a clear difference in the size of fish chased versus the size of fish confirmed to be captured and shared with other members of the pod, suggesting that the whales may be selectively targeting certain size or age classes of fish. Most of the fish observed within the study were determined to be Chinook salmon with the possibility of other salmonid species also being preyed upon. Of the 18 successful foraging events, prey-sharing occurred 88% of the time, with 62.5% of prey-sharing behavior occurring between mothers and calves. This knowledge is important to the successful management and protection of this unique and critically endangered population. Knowing targeted species and size classes of fish can allow for better fishing and recovery strategies, which may lead to increased foraging success of the SRKWs.

This paper reviews genetic studies undertaken to generate an accurate phylogeny of killer whale (Orcinus orca) lineages. Three phylogenies, distinct in branching order and timing of divergences, are discussed. Of the three phylogenies, two are based on mitochondrial DNA and show more ancient divergence times for killer whale lineages. The third phylogeny, based on nuclear DNA, indicates that killer whales diversified more recently. The differing phylogenies have differing implications for biogeographic inference and for species assessments. The nuclear based phylogeny suggests that killer whale lineages diverged in sympatry while the mitochondrial based phylogenies as well as an empirical study indicate that the divergences more likely occurred in allopatry. The mitochondrial based phylogenies also support revision of killer whale taxonomy as there is indication that killer whales constitute multiple species and subspecies instead of a single species. The types of research that would be helpful in confirming hypotheses based on the phylogenies are discussed.

The endangered Southern Resident Killer Whale (SRKW) population is an icon of the Pacific Northeast. The population has experienced a 10 percent decline in population since 2005 and now number only 76 individuals, the lowest abundance in more than 30 years. The SRKWs have been shown to be food-limited with declines in survival and reproduction in years following low salmon availability. Diet studies conducted on the SRKWs have shown a strong prey preference for Chinook salmon (Oncorhynchus tshawytscha) in the summer, yet uncertainty remains about prey preferences and foraging behavior. To help fill this data gap, I used high-resolution aerial images to quantify and describe foraging behavior from a new perspective. Specifically, I reviewed images collected by a small unmanned hexacopter during five individual month-long field efforts between 2015 and 2017. From this collection 29 distinct foraging events were documented in 2,384 images that allowed for photogrammetry measurements of fish size, and species identification of fish preyed upon. The data show that there is a clear difference in the size of fish chased versus the size of fish confirmed to be captured and shared with other members of the pod, suggesting that the whales may be selectively targeting certain size or age classes of fish. Most of the fish observed within the study were determined to be Chinook salmon with the possibility of other salmonid species also being preyed upon. Of the 18 successful foraging events, prey-sharing occurred 88% of the time, with 62.5% of prey-sharing behavior occurring between mothers and calves. This knowledge is important to the successful management and protection of this unique and critically endangered population. Knowing targeted species and size classes of fish can allow for better fishing and recovery strategies, which may lead to increased foraging success of the SRKWs.

This paper reviews genetic studies undertaken to generate an accurate phylogeny of killer whale (Orcinus orca) lineages. Three phylogenies, distinct in branching order and timing of divergences, are discussed. Of the three phylogenies, two are based on mitochondrial DNA and show more ancient divergence times for killer whale lineages. The third phylogeny, based on nuclear DNA, indicates that killer whales diversified more recently. The differing phylogenies have differing implications for biogeographic inference and for species assessments. The nuclear based phylogeny suggests that killer whale lineages diverged in sympatry while the mitochondrial based phylogenies as well as an empirical study indicate that the divergences more likely occurred in allopatry. The mitochondrial based phylogenies also support revision of killer whale taxonomy as there is indication that killer whales constitute multiple species and subspecies instead of a single species. The types of research that would be helpful in confirming hypotheses based on the phylogenies are discussed.

Environmental enrichment is critical for maintaining cognitive welfare for animals in human care but is subject to individual preferences. The interest in a video-based enrichment was assessed for a single killer whale (Orcinus orca) in human care. The adult female was presented 20 video recordings featuring cetaceans, elephants, or humans with each video presented in two conditions: (1) with sound and (2) without sound. Four additional presentations in which the television displayed a blank screen served as controls. All sessions were videotaped and coded for time spent viewing the recordings, behavioral responses, and visual laterality. The killer whale spent significantly more time at the television when programs were on screen compared to when the television was present but blank. She was more likely to watch videos accompanied by sound than those presented without sound. Videos were more likely to be viewed monocularly rather than binocularly, with a right eye preference when viewing the videos the first time they were presented. The highest rates of behavioral responses occurred during videos of cetaceans. These results demonstrate that one killer whale responded to video recordings of different stimuli, suggesting that video recordings may be used as a form of enrichment for cetaceans and that not all video content and formats are equally interesting.

Environmental enrichment is critical for maintaining cognitive welfare for animals in human care but is subject to individual preferences.  The interest in a video-based enrichment was assessed for a single killer whale ( Orcinus orca ) in human care.  The adult female was presented 20 video recordings featuring cetaceans, elephants, or humans with each video presented in two conditions: (1) with sound and (2) without sound.  Four additional presentations in which the television displayed a blank screen served as controls.  All sessions were videotaped and coded for time spent viewing the recordings, behavioral responses, and visual laterality.  The killer whale spent significantly more time at the television when programs were on screen compared to when the television was present but blank.  She was more likely to watch videos accompanied by sound than those presented without sound. Videos were more likely to be viewed monocularly rather than binocularly, with a right eye preference when viewing the videos the first time they were presented.  The highest rates of behavioral responses occurred during videos of cetaceans.  These results demonstrate that one killer whale responded to video recordings of different stimuli, suggesting that video recordings may be used as a form of enrichment for cetaceans and that not all video content and formats are equally interesting.

The primary prey of killer whales (Orcinus orca) in the Strait of Gibraltar is the bluefin tuna (Thunnus thynnus). All killer whales observed in this area hunt tuna by chasing individual fish until they become exhausted and can be overcome. However, a subset of pods also interact with a dropline tuna fishery which has developed since 1995. Here, we investigated the social structure within and among social units (pods). Our data suggested that social structure was shaped by maternal kinship, which appears to be a species-specific trait, but also by foraging behavior, which is less common at the intra-population level. At the start of the study, only one cohesive pod interacted with the fishery, which during the course of the study underwent fission into two socially differentiated pods. Social structure within these two fishery-interacting pods was more compact and homogenous with stronger associations between individuals than in the rest of the population. Three other pods were never seen interacting with the fishery, despite one of these pods being regularly sighted in the area of the fishery during the summer. Sociality can influence the spread of the novel foraging behaviors and may drive population fragmentation, which, in this example, is already a critically small community. Observations of social changes in relation to changes in foraging at the earliest stages of diversification in foraging behavior and social segregation may provide insights into the processes that ultimately result in the formation of socially isolated discrete ecotypes in killer whales.

Species are vital entities in biology. Species are generally considered to be discrete entities, consisting of a group of (usually interbreeding) individuals that are similar in phenotype and genetic composition, yet differ in significant ways from other species. The study of speciation has focussed on understanding general evolutionary mechanisms involved in the accumulation of differences both at the genetic and phenotypic level. In this thesis, I investigate incipient speciation, an early stage of divergence towards evolutionary independence in closely related natural populations. I make ample use of recent advances in sequencing technology that allow 1) characterizing phenotypic divergence at the level of the transcriptome and 2) delineate patterns of genetic variation at genome-scale from which processes are inferred by using principles of population genetic theory. In the first paper, we assembled a draft genome of the hooded crow and investigated population differentiation across a famous European hybrid zone. Comparing sequence differentiation peaks between and within the colour morphs, we could identify regions of the genome that show differentiation only between colour morphs and that could be related to gene expression profiles of the melanogenesis pathway coding for colour differences. The second paper expands on the first paper in that it includes crow population samples from across the entire Palaearctic distribution spanning two additional zones of contact between colour morphs. The results suggest that regions associated with selection against gene flow between colour morphs were largely idiosyncratic to each contact zone and emerged against a background of conserved 'islands of differentiation' due to shared linked selection. The third paper focusses on five killer whale ecotypes with distinct feeding and habitat specific adaptations. Differing levels of sequence differentiation between these ecotypes places them along a speciation continuum and pro

In odontocetes, synchronous visible displays accompany a small proportion of vocalizations but the function of these multimodal signals is still unclear. Bouts of stereotyped pulsed calls were collected from two adult female killer whales (Orcinus orca) concurrently with behavioral observations and the incidence of two synchronous behaviors, bubble streams and nodding, were measured. Thirty-four hours of focal individual data were collected in the presence of dependent calves in 1993 and 1994. Overall, 471 pulsed calls were attributed to the two subjects using synchronous behaviors or independent cues (proximity, localization by ear in air). Both subjects used the same stereotyped pulsed call repertoire and they ordered calls within bouts similarly, despite dissimilar previous histories. Both nodding and bubble streams were disproportionately associated with a subset of stereotyped pulsed calls, but the subset was different for the two behaviors. General Linear Model analysis was used to predict the relative odds that the subjects would be swimming with calves given call class and attribution cue. Bubbling was not associated with significant odds that a subject would be swimming with one or more calves, but nodding was associated with significantly higher odds and resting calls with lower odds. Given these observations, synchronous behaviors in the presence of calves could function in one or more of the following ways: altering the signal value of calls, emphasizing an aspect of the social context, and facilitating learning. All are possibilities at the interface between cognition and communication that would have interested Stan Kuczaj.

Species are vital entities in biology. Species are generally considered to be discrete entities, consisting of a group of (usually interbreeding) individuals that are similar in phenotype and genetic composition, yet differ in significant ways from other species. The study of speciation has focussed on understanding general evolutionary mechanisms involved in the accumulation of differences both at the genetic and phenotypic level. In this thesis, I investigate incipient speciation, an early stage of divergence towards evolutionary independence in closely related natural populations. I make ample use of recent advances in sequencing technology that allow 1) characterizing phenotypic divergence at the level of the transcriptome and 2) delineate patterns of genetic variation at genome-scale from which processes are inferred by using principles of population genetic theory. In the first paper, we assembled a draft genome of the hooded crow and investigated population differentiation across a famous European hybrid zone. Comparing sequence differentiation peaks between and within the colour morphs, we could identify regions of the genome that show differentiation only between colour morphs and that could be related to gene expression profiles of the melanogenesis pathway coding for colour differences. The second paper expands on the first paper in that it includes crow population samples from across the entire Palaearctic distribution spanning two additional zones of contact between colour morphs. The results suggest that regions associated with selection against gene flow between colour morphs were largely idiosyncratic to each contact zone and emerged against a background of conserved 'islands of differentiation' due to shared linked selection. The third paper focusses on five killer whale ecotypes with distinct feeding and habitat specific adaptations. Differing levels of sequence differentiation between these ecotypes places them along a speciation continuum and pro

In odontocetes, synchronous visible displays accompany a small proportion of vocalizations but the function of these multimodal signals is still unclear.  Bouts of stereotyped pulsed calls were collected from two adult female killer whales ( Orcinus orca ) concurrently with behavioral observations and the incidence of two synchronous behaviors, bubble streams and nodding, were measured.  Thirty-four hours of focal individual data were collected in the presence of dependent calves in 1993 and 1994.  Overall, 471 pulsed calls were attributed to the two subjects using synchronous behaviors or independent cues (proximity, localization by ear in air).  Both subjects used the same stereotyped pulsed call repertoire and they ordered calls within bouts similarly, despite dissimilar previous histories.  Both nodding and bubble streams were disproportionately associated with a subset of stereotyped pulsed calls, but the subset was different for the two behaviors.  General Linear Model analysis was used to predict the relative odds that the subjects would be swimming with calves given call class and attribution cue.  Bubbling was not associated with significant odds that a subject would be swimming with one or more calves, but nodding was associated with significantly higher odds and resting calls with lower odds.  Given these observations, synchronous behaviors in the presence of calves could function in one or more of the following ways: altering the signal value of calls, emphasizing an aspect of the social context, and facilitating learning.  All are possibilities at the interface between cognition and communication that would have interested Stan Kuczaj.

Species are vital entities in biology. Species are generally considered to be discrete entities, consisting of a group of (usually interbreeding) individuals that are similar in phenotype and genetic composition, yet differ in significant ways from other species. The study of speciation has focussed on understanding general evolutionary mechanisms involved in the accumulation of differences both at the genetic and phenotypic level. In this thesis, I investigate incipient speciation, an early stage of divergence towards evolutionary independence in closely related natural populations. I make ample use of recent advances in sequencing technology that allow 1) characterizing phenotypic divergence at the level of the transcriptome and 2) delineate patterns of genetic variation at genome-scale from which processes are inferred by using principles of population genetic theory. In the first paper, we assembled a draft genome of the hooded crow and investigated population differentiation across a famous European hybrid zone. Comparing sequence differentiation peaks between and within the colour morphs, we could identify regions of the genome that show differentiation only between colour morphs and that could be related to gene expression profiles of the melanogenesis pathway coding for colour differences. The second paper expands on the first paper in that it includes crow population samples from across the entire Palaearctic distribution spanning two additional zones of contact between colour morphs. The results suggest that regions associated with selection against gene flow between colour morphs were largely idiosyncratic to each contact zone and emerged against a background of conserved 'islands of differentiation' due to shared linked selection. The third paper focusses on five killer whale ecotypes with distinct feeding and habitat specific adaptations. Differing levels of sequence differentiation between these ecotypes places them along a speciation continuum and pro

Species are vital entities in biology. Species are generally considered to be discrete entities, consisting of a group of (usually interbreeding) individuals that are similar in phenotype and genetic composition, yet differ in significant ways from other species. The study of speciation has focussed on understanding general evolutionary mechanisms involved in the accumulation of differences both at the genetic and phenotypic level. In this thesis, I investigate incipient speciation, an early stage of divergence towards evolutionary independence in closely related natural populations. I make ample use of recent advances in sequencing technology that allow 1) characterizing phenotypic divergence at the level of the transcriptome and 2) delineate patterns of genetic variation at genome-scale from which processes are inferred by using principles of population genetic theory. In the first paper, we assembled a draft genome of the hooded crow and investigated population differentiation across a famous European hybrid zone. Comparing sequence differentiation peaks between and within the colour morphs, we could identify regions of the genome that show differentiation only between colour morphs and that could be related to gene expression profiles of the melanogenesis pathway coding for colour differences. The second paper expands on the first paper in that it includes crow population samples from across the entire Palaearctic distribution spanning two additional zones of contact between colour morphs. The results suggest that regions associated with selection against gene flow between colour morphs were largely idiosyncratic to each contact zone and emerged against a background of conserved 'islands of differentiation' due to shared linked selection. The third paper focusses on five killer whale ecotypes with distinct feeding and habitat specific adaptations. Differing levels of sequence differentiation between these ecotypes places them along a speciation continuum and pro

Species are vital entities in biology. Species are generally considered to be discrete entities, consisting of a group of (usually interbreeding) individuals that are similar in phenotype and genetic composition, yet differ in significant ways from other species. The study of speciation has focussed on understanding general evolutionary mechanisms involved in the accumulation of differences both at the genetic and phenotypic level. In this thesis, I investigate incipient speciation, an early stage of divergence towards evolutionary independence in closely related natural populations. I make ample use of recent advances in sequencing technology that allow 1) characterizing phenotypic divergence at the level of the transcriptome and 2) delineate patterns of genetic variation at genome-scale from which processes are inferred by using principles of population genetic theory. In the first paper, we assembled a draft genome of the hooded crow and investigated population differentiation across a famous European hybrid zone. Comparing sequence differentiation peaks between and within the colour morphs, we could identify regions of the genome that show differentiation only between colour morphs and that could be related to gene expression profiles of the melanogenesis pathway coding for colour differences. The second paper expands on the first paper in that it includes crow population samples from across the entire Palaearctic distribution spanning two additional zones of contact between colour morphs. The results suggest that regions associated with selection against gene flow between colour morphs were largely idiosyncratic to each contact zone and emerged against a background of conserved 'islands of differentiation' due to shared linked selection. The third paper focusses on five killer whale ecotypes with distinct feeding and habitat specific adaptations. Differing levels of sequence differentiation between these ecotypes places them along a speciation continuum and pro

The primary prey of killer whales (Orcinus orca) in the Strait of Gibraltar is the bluefin tuna (Thunnus thynnus). All killer whales observed in this area hunt tuna by chasing individual fish until they become exhausted and can be overcome. However, a subset of pods also interact with a dropline tuna fishery which has developed since 1995. Here, we investigated the social structure within and among social units (pods). Our data suggested that social structure was shaped by maternal kinship, which appears to be a species-specific trait, but also by foraging behavior, which is less common at the intra-population level. At the start of the study, only one cohesive pod interacted with the fishery, which during the course of the study underwent fission into two socially differentiated pods. Social structure within these two fishery-interacting pods was more compact and homogenous with stronger associations between individuals than in the rest of the population. Three other pods were never seen interacting with the fishery, despite one of these pods being regularly sighted in the area of the fishery during the summer. Sociality can influence the spread of the novel foraging behaviors and may drive population fragmentation, which, in this example, is already a critically small community. Observations of social changes in relation to changes in foraging at the earliest stages of diversification in foraging behavior and social segregation may provide insights into the processes that ultimately result in the formation of socially isolated discrete ecotypes in killer whales.

Since its national debut in 1987, Fresh Air with Terry Gross has been a highly acclaimed and much adored weekday magazine among public radio listeners. Each week, nearly 4.8 million people turn to Peabody Award-winning host Terry Gross for insightful conversations with the leading voices in contemporary arts and issues. The renowned program reaches a global audience, with over 620 public radio stations broadcasting Fresh Air, and 3 million podcast downloads each week. Fresh Air has broken the mold of 'talk show' by weaving together superior journalism and intimate storytelling from modern-day intellectuals, politicians and artists alike. Through probing questions and careful research, Gross's interviews are lauded for revealing a fresh perspective on cultural icons and trends. Her thorough conversations are often complemented by commentary from well-known contributors. Fresh Air is produced at WHYY-FM in Philadelphia and broadcast nationally by NPR., (1.) Former senior orca trainer for the marine park SeaWorld, JOHN HARGROVE. He quit in 2012 after 14 years. Two marine park trainers were killed by whales, and he was nearly killed. He now believes whales should not be held in captivity. HARGROVE is featured in the documentary Blackfish, and is the author of the new book Beneath the Surface: Killer Whales, Seaworld, and the Truth Beyond Blackfish. (INTERVIEW BY DAVE DAVIES). (2.) We hear from two Seaworld representatives: CHUCK TOMPKINS, Corporate Curator of Zoological Operations, and CHRIS DOLD, Vice President of Veterinary Services. (INTERVIEW BY DAVE DAVIES).

Killer whales have been described in the Gulf of Cadiz, southern Spain, in spring and in the Strait of Gibraltar in summer. A total of 11,276 cetaceans sightings coming from different sources (dedicated research surveys, whale watching companies and opportunistic observations) were used to create two presence–‘pseudo-absence’ predictive generalized additive models (GAM), where presence data were defined as sightings of killer whales and ‘pseudo-absence’ data as sightings of other cetacean species. One model was created using spring data when killer whales’ main prey, Atlantic bluefin tuna, enter the Mediterranean Sea, and the other model used summer data when Atlantic bluefin tuna return to the Atlantic Ocean. Both model predictions show that killer whales are highly associated with a probable distribution of bluefin tuna during their migration throughout the study area, constraining their distribution to the Gulf of Cadiz in spring and the Strait of Gibraltar in spring and summer. Knowledge of the distribution of killer whales in the study area is essential to establish conservation measures for this population.

Killer whales have been described in the Gulf of Cadiz, southern Spain, in spring and in the Strait of Gibraltar in summer. A total of 11,276 cetaceans sightings coming from different sources (dedicated research surveys, whale watching companies and opportunistic observations) were used to create two presence–‘pseudo-absence’ predictive generalized additive models (GAM), where presence data were defined as sightings of killer whales and ‘pseudo-absence’ data as sightings of other cetacean species. One model was created using spring data when killer whales’ main prey, Atlantic bluefin tuna, enter the Mediterranean Sea, and the other model used summer data when Atlantic bluefin tuna return to the Atlantic Ocean. Both model predictions show that killer whales are highly associated with a probable distribution of bluefin tuna during their migration throughout the study area, constraining their distribution to the Gulf of Cadiz in spring and the Strait of Gibraltar in spring and summer. Knowledge of the distribution of killer whales in the study area is essential to establish conservation measures for this population.

Critical habitats of at-risk populations of northeast Pacific ‘‘resident’’ killer whales can be heavily trafficked by large ships, with transits occurring on average once every hour in busy shipping lanes. We modeled behavioral responses of killer whales to ship transits during 35 ‘‘natural experiments’’ as a dose–response function of estimated received noise levels in both broadband and audiogram-weighted terms. Interpreting effects is contingent on a subjective and seemingly arbitrary decision about severity threshold indicating a response. Subtle responses were observed around broadband received levels of130 dB re 1 µPa (rms); more severe responses are hypothesized to occur at received levels beyond 150 dB re 1 µPa, where our study lacked data. Avoidance responses are expected to carry minor energetic costs in terms of increased energy expenditure, but future research must assess the potential for reduced prey acquisition, and potential population consequences, under these noise levels.

An animal’s foraging ecology can vary over a range of temporal scales, mirroring seasonal and longer term changes in prey availability, as well as ontogenetic shifts in diet and distribution. Obtaining individual-based, longitudinal diet information through direct observation, however, is logistically challenging for marine mammals that pursue and consume prey underwater, and are often widely distributed. Isotopic profiling along continuously growing tissues like teeth and baleen, which archive dietary inputs at the time of growth in their stable isotope composition, allows for chronological dietary reconstructions over multi-year timespans. This thesis reports longitudinal diet studies of three Arctic whale species, killer whales (Orcinus orca), bowhead whales (Balaena mysticetus) and beluga whales (Delphinapterus leucas), derived from serial isotopic measurements along teeth and baleen. Study objectives varied by species, but general goals were to characterize seasonal, ontogenetic, and/or individual diet variation. Results revealed similar trophic-level diet, but regional spatial separation, among eastern Canadian Arctic/Northwest Atlantic killer whales. However, isotope and tooth wear differences between two individuals and the rest of the sampled whales suggested potential specialisation on sharks, while the other whales likely had diets comprising marine mammals. Cyclic isotopic variation along Eastern Canada-West Greenland bowhead whale baleen was consistent with year-round foraging, although at a reduced rate during winter. Resting zooplankton could be an important food resource outside of periods of peak productivity, and accessibility likely drives winter habitat selection. Isotopic cycling did not differ between female and male bowheads, or among age classes, indicating similar seasonal foraging patterns despite reported spatial segregation throughout their summer range. Individual beluga whales from three eastern Canadian Arctic populations varied in tim

Identifying evolutionary divergent taxonomic units, e.g. species and subspecies, is important for conservation and evolutionary biology. The 'type D' killer whale, Orcinus orca, is a rarely observed morphotype with a pelagic, circumpolar subantarctic distribution, making dedicated research and therefore taxonomic study extremely difficult to date. In this study, we used DNA target enrichment hybridisation capture coupled to high throughput sequencing, to obtain the first DNA sequence from the only known museum specimen of this recently described morphotype. The high coverage, complete mitogenome sequence was compared to a previously published global dataset of 139 individuals, indicating that this type is highly divergent to all previously genetically sequenced killer whale forms. The estimated divergence time (390,000 years ago) from its most recent common ancestor with other extant killer whale lineages was the second oldest split within the killer whale phylogeny. This study provides the first genetic support of type D potentially being a distinct subspecies or species of killer whale, although further samples are needed to identify whether there is monophyly of mitogenome sequences and whether nuclear DNA also indicates reproductive isolation. These findings also highlight the value of natural history museum collections and new technologies to investigate the taxonomy of rare, cryptic or difficult to access species