Detection of specific antibodies to morbilliviruses, Brucella and Toxoplasma in the Black Sea dolphin Tursiops truncatus ponticus and the beluga whale Delphinapterus leucas from the Sea of Okhotsk in 2002–2007

The prevalence of antibodies to morbilliviruses, Brucella and Toxoplasma was studied in the Black Sea bottlenose dolphin Tursiops truncatus ponticus and the beluga whale Delphinapterus leucas from the Sea of Okhotsk. The blood serum of 74 dolphins and 147 beluga whales was tested in 2002–2007. Antibodies to morbilliviruses were detected in 15 (20.3%) bottlenose dolphins and 20 (13.6%) beluga whales. Antibodies to Brucella were detected in 17 (23.0%) bottlenose dolphins and 10 (6.8%) beluga whales. Toxoplasma-specific antibodies were detected in 39 (52.7%) bottlenose dolphins and 7 (4.8%) beluga whales. Some animals had antibodies to two, or even three, of the pathogens. A high level of incidence of the pathogens in the sea animals was found in the densely populated coastal areas with high economic development.     

Larger body size leads to greater female beluga whale ovarian reproductive activity at the southern periphery of their range

Identification of phenotypic characteristics in reproductively successful individuals provides important insights into the evolutionary processes that cause range shifts due to environmental change. Female beluga whales (Delphinapterus leucas) from the Baffin Bay region (BB) of the Canadian Arctic in the core area of the species’ geographic range have larger body size than their conspecifics at the southern range periphery in Hudson Bay (HB). We investigated the mechanism for this north and south divergence as it relates to ovarian reproductive activity (ORA = total corpora) that combines morphometric data with ovarian corpora counted from female reproductive tracts. Our study aim was to assess the relative influence of age and body size of female beluga whale on ORA in the two populations. Female beluga whale ORA increased more quickly with age (63% partial variation explained) in BB than in HB (41%). In contrast, body length in HB female beluga whales accounted for considerably more of the total variation (12% vs. 1%) in ORA compared to BB whales. We speculate that female HB beluga whale ORA was more strongly linked with body length due to higher population density resulting in food competition that favors the energetic advantages of larger body size during seasonal food limitations. Understanding the evolutionary mechanism of how ORA varies across a species’ range will assist conservation efforts in anticipating and mitigating future challenges associated with a warming planet.     

Killer whale (Orcinus orca) predation in a multi-prey system

Predation can regulate prey numbers but predator behaviour in multiple-prey systems can complicate understanding of control mechanisms. We investigate killer whale (Orcinus orca) predation in an ocean system where multiple marine mammal prey coexist. Using stochastic models with Monte-Carlo simulations, we test the most likely outcome of predator selection and compare scenarios where killer whales: (1) focus predation on larger prey which presumably offer more energy per effort, (2) generalize by feeding on prey as encountered during searches, or (3) follow a mixed foraging strategy based on a combination of encounter rate and prey size selection. We test alternative relationships within the Hudson Bay geographic region, where evidence suggests killer whales seasonally concentrate feeding activities on the large-bodied bowhead whale (Balaena mysticetus). However, model results indicate that killer whales do not show strong prey specialization and instead alternatively feed on narwhal (Monodon monoceros) and beluga (Delphinapterus leucas) whales early and late in the ice-free season. Evidence does support the conjecture that during the peak of the open water season, killer whale predation can differ regionally and feeding techniques can focus on bowhead whale prey. The mixed foraging strategy used by killer whales includes seasonal predator specialization and has management and conservation significance since killer whale predation may not be constrained by a regulatory functional response.     

Sentient Beings and Wildlife Resources: Inuit,Beluga Whales and Management Regimes in the Canadian Arctic

Beluga whale hunting is one of the most social subsistence hunting activities to take place in the Canadian Arctic. Through the harvest, distribution and consumption of beluga whales, Inuit identity and social relationships are affirmed. The whale-hunting complex is influenced by beliefs that beluga whales are sentient beings who inhabit a shared social space with humans. Yet, across the region beluga whales are perceived by wildlife managers as scarce resources and as such require protection through the imposition of management plans. There is currently no management of whales on the west coast of Hudson Bay, in Nunavut. In 2002, Inuit there were requested to sell part of their whale harvest to Inuit in Nunavik, northern Quebec, where hunting quotas exist. The outcome of this event was concern in Nunavut for the future of the whale hunt, and a deepening sense of powerlessness in Nunavik due to the management of the whale harvest.

A genetic analysis of the beluga whale Delphinapterus leucas (Cetacea: Monodontidae) from summer aggregations in the Russian Far East

The genetic structure of four summer aggregations of the Beluga Whale, Delphinapterus leucas, in Sakhalin Bay and Udskaya Bay, off the western coast of Kamchatka in the Sea of Okhotsk and in the Anadyr Estuary of the Bering Sea was analyzed through nucleotide sequencing of the mtDNA control region and detection of the allelic composition of nine microsatellite loci in nuclear DNA. It has been shown that each of the aggregations features a unique set of maternal lines, which indicates a high degree of philopatry in this species. Beluga whales of the Anadyr Estuary are genetically isolated from those of the Sea of Okhotsk. Beluga whales of the summer aggregations of Sakhalin Bay and those from Udskaya Bay share a common gene pool and belong to a single population, while the whales that summer off western Kamchatka with great consistency may be attributed to a different population. Comparison of nucleotide sequences of the mtDNA in beluga whales from various waters of the Russian Far East and North America allowed us to propose a hypothesis about how the structure of beluga whale populations formed in the North Pacific during the postglacial period.     

Winter distribution and migrations of beluga whales (<Emphasis Type="Italic">Delphinapterus leucas</Emphasis>) in the White Sea based on satellite tracking data

Based on satellite tracking of eight beluga whale males in the White Sea, their habitats in the autumn, winter, and spring periods have been identified. A correlation between the distribution of beluga whales, ice dynamics, and migration of Atlantic salmon has been revealed. It has been found than beluga whale males do not leave the White Sea during the entire ice period. The results obtained confirm the hypothesis that the White Sea population of beluga whales is isolated.     

Matriarchal genetic population structure of North American beluga whales Delphinapterus leucas (Cetacea: Monodontidae)

The North American beluga whale Delphinapterus leucas population has been divided into a number of putative geographical stocks based upon migration routes and areas of summer concentration. Nucleotide sequences of the mitochondrial DNA (mtDNA) control region were used to assess whether these geographical stocks are genetically distinct. Beluga whale samples from 25 sites were collected primarily from aboriginal subsistence hunts across North America from 1984 to 1994. Thirty-nine mtDNA haplotypes were identified in 628 beluga samples. No differences were found in the distribution of haplotypes between male and female beluga whales at any sampling site. These haplotypes segregated into two distinct assemblages in both a haplotype network and a neighbour-joining tree. The haplotype assemblages had a geographically disjunct distribution that suggests postglacial recolonization of the North American Arctic from two different refugia.
An analysis of molecular variance based on haplotype relationships and frequency indicated genetic heterogeneity among beluga whale summering groups ( P ≤ 0.001). Sequence divergence estimates between sampling sites also indicated geographical differentiation, particularly between samples taken at east Hudson Bay or St Lawrence River and the western or central Arctic. The results of this study show a high degree of philopatry to specific summering areas by this highly mobile animal.     

KILLER WHALES, ORCINUS ORCA, IN THE SOUTHEASTERN BERING SEA: RECENT SIGHTINGS andPREDATION ON OTHER MARINE MAMMALS

An unusual number of killer whales appeared in inshore waters of the southeastern Bering Sea in summer 1989 and 1990. Multiple sightings occurred in Bristol and Kuskokwim bays where killer whales had been seen only rarely in previous years. Three animals became stranded on mud flats in Kuskokwim Bay but were able to free themselves on a high tide. Killer whales were observed interacting with salmon, harbor seals, Steller sea lions, walruses, and beluga whales. Detailed observations were made of killer whales attacking belugas in the Naknek River. Local conditions and behavioral adaptations may reduce the susceptibility of belugas to killer whale predation. Continued killer whale activity in this area would be unlikely to affect fish resources, but might have some influence on beluga whales.     

Analysis of a Blainville's beaked whale's movement response to playback of killer whale vocalizations

Increasing evidence links exposure to Navy sonar with certain mass stranding events of deep diving beaked whales. Although the cause of these strandings is unknown, one theory suggests that the animals confuse the sonar signals with vocalizations of killer whales, a known predator. Here we analyze the movement patterns of a tagged female Blainville's beaked whale in reaction to playback of killer whale predation calls. During a deep foraging dive, the whale was exposed to a playback of killer whale vocalizations with the source level slowly increased until the whale prematurely ceased foraging. The heading data from the tag were analyzed using a rotation test with a likelihood ratio calculated for a nonparametric kernel density estimate. We found a significant difference (P < 0.005) in the distribution of Δheading (the change in heading averaged over 200 s) after the cessation of the killer whale playback. A test of the angular standard deviation (SD) of the Δheading showed that after the playback, the SD was significantly reduced (P = 0.0064), which indicates that the animal maintained a straighter than normal course for an extended period of time. The prolonged directed avoidance response observed here suggests a behavioral reaction that could pose a risk factor for stranding.     

A new species of baleen whale (Balaenoptera) from the Gulf of Mexico,with a review of its geographic distribution

Bryde's-like whales are a complex of medium-sized baleen whales that occur in tropical waters of all three major ocean basins. Currently, a single species of Bryde's whale, Balaenoptera edeni Anderson, 1879, is recognized, with two subspecies, Eden's whale, B. edeni edeni and Bryde's whale, B. edeni brydei (Olsen, 1913), although some authors have recognized these as separate species. Recently, a new, evolutionarily divergent lineage of Bryde's-like whale was identified based on genetic data and was found to be restricted primarily to the northern Gulf of Mexico (GOMx). Here, we provide the first morphological examination of a complete skull from these whales and identify diagnostic characters that distinguish it from the other medium-sized baleen whale taxa. In addition, we have increased the number of genetic samples of these Bryde's-like whales in the GOMx from 23 to 36 individuals, all of which matched the GOMx lineage. A review of Bryde's-like whale records in the Caribbean and greater Atlantic supports an isolated distribution for this unique lineage, augmenting the genetic and morphological body of evidence supporting the existence of an undescribed species of Balaenoptera from the Gulf of Mexico.     

KILLER WHALE PREDATION ON BELUGAS IN COOK INLET, ALASKA: IMPLICATIONS FOR A DEPLETED POPULATION

Killer whale predation on belugas in Cook Inlet, Alaska, has become a concern since the decline of these belugas was documented during the 1990s. Accordingly, killer whale sightings were compiled from systematic surveys, observer databases, and anecdotal accounts. Killer whales have been relatively common in lower Cook Inlet (at least 100 sightings from 1975 to 2002), but in the upper Inlet, north of Kalgin Island, sightings were infrequent (18 in 27 yr), especially prior to the 1990s. Beach cast beluga carcasses with teeth marks and missing flesh also provided evidence of killer whale predation. Most observed killer whale/beluga interactions were in the upper Inlet. During 11 of 15 observed interactions, belugas were obviously injured or killed, either through direct attacks or indirectly as a result of stranding. Assuming at least one beluga mortality occurred during the other four encounters, we can account for 21 belugas killed between 1985 and 2002. This would suggest a minimum estimate of roughly 1/yr and does not include at least three instances where beluga calves accompanied an adult that was attacked.     

Interactions between Cetacean and Fisheries in the Southern Ocean

Soon after longlining on Patagonian toothfish (Dissostichus eleginoides) started in the Southern Ocean in the second half of the 1980s, interactions of cetaceans with these fisheries became apparent. The two species primarily involved were orcas (killer whales) (Orcinus orca) and male sperm whales (Physeter macrocephalus). Both species took substantial number of fish from the line primarily during day light hours. Catch rates of longliners declined to less than 50% when orcas occurred close to longline vessels while the loss to sperm whales was much less obvious. They were seen diving close to the line down to 400 m where they apparently took fish. Their impact on catch rates was much less notable. Sperm whales became frequently entangled in the line and part of the line was lost in a number of cases. Other cetaceans were rarely seen in the vicinity of longline vessels. They became entangled in the line only occasionally and one whale (presumably a minke whale) died.     

Stable carbon and nitrogen isotope ratios in muscle and epidermis of arctic whales

Collection of minimally invasive biopsy samples has become an important method to establish normal stable isotopes reference ranges in various wildlife species. Baseline data enhance the understanding of feeding ecology, habitat use, and potential food limitation in apparently healthy, free‐ranging cetaceans. Epidermis and muscle were collected from subsistence‐hunted northern Alaskan bowhead (n= 133 epidermis/134 muscle) and beluga whales (n= 42/49) and subsistence‐hunted Russian gray whales (n= 25/17). Additional samples were obtained from gray whales stranded in California (n= 18/11) during mortality events (1999, 2000). Both δ¹⁵N and δ¹³C are trophic position and benthic/pelagic feeding indicators, respectively, in muscle and epidermis. Epidermis is generally enriched in ¹⁵N over muscle, while epidermal ¹³C is more depleted. Lipid extraction does not alter δ¹⁵N in either tissue, but affects epidermal δ¹³C. Nitrogen‐15 is enriched in muscle, but not epidermis of stranded compared to subsistence‐hunted gray whales, indicating probable protein catabolism and nutritional stress in stranded whales. Similarly, epidermal δ¹³C of harvested whales is lower than in stranded whales, suggesting depleted lipid stores and/or food limitation in stranded animals. Epidermal isotope signatures are similar in both present‐day bowheads and in an ancient sample from the Northern Bering Sea region. Although only one specimen, this suggests trophic level of the ancient whale compares to modern bowheads after a millennium.     

Fin whale (Balaenoptera physalus) target strength measurements

Active acoustic techniques can be used to detect whales. The ability to detect whales from a moving vessel or stationary buoy could reduce conflicts between hazardous human activities and whales, enabling implementation of mitigation procedures. In order to identify acoustic targets correctly as whales, knowledge of whale target strength (TS) is required. Active acoustic detections of fin whales (Balaenoptera physalus) were made in the Norwegian Sea; acoustic data were collected using calibrated omnidirectional sonar, operating at a discrete frequency of 110 kHz. Three fin whales of similar size (estimated between 16 and 18 m total length) had an overall average TS for all insonified body aspects of ?11.4 dB [95% CI ?12.05, ?10.8] at 110 kHz, with a total spread of nearly 14 dB. As expected, the received signals were stronger when the fin whales were insonified at broadside (?5.6 dB). Individual fin whale TS varied by approximately 12 dB, probably due to variation in lung volume with breathing, and to dynamic swimming kinematics. Our TS values are consistent with values reported previously for other large whales. All data together pave the way for development of automated acoustic whale detection protocols that could aid whale conservation.     

First report on the stomach contents of long‐finned pilot whales,Globicephala melas,stranded in New Zealand

Abstract

Stomach contents of the long‐finned pilot whale, Globicephala melas, are reported for the first time from New Zealand waters. Analyses based on two male and three female whales (2.5–5.3 m in length) that stranded on Farewell Spit, Golden Bay, South Island in December 2005 revealed a diet comprised exclusively of cephalopods (2-33 lower cephalopod beaks per stomach). Two genera of cephalopod from two orders; arrow squid, Nototodarus spp. (Teuthoidea: Ommastrephidae), and common octopus, Pinnoctopus cordiformis (Octopoda: Octopodidae) were represented. A further five pilot whale stomachs were examined and found to be empty.     

Analysis of the C4 genes in baleen whales using a human cDNA probe

We have used a human C4 cDNA probe to investigate the complement component C4 gene in four members of the family Balaenopteridae: fin whale (Balaenoptera physalus), sei whale (B. borealis), minke whale (B. acutorostrata), and bryde's whale (B. edeni). Restriction mapping of genomic DNA from the first three species suggests the presence of only one locus in these species, and also shows that the C4 genes in the three species are very similar. We have used 14 restriction endonucleases to investigate the restriction fragment length polymorphism (RFLP) of fin whales, 13 enzymes for sei whales, and 8 enzymes for the minke whale. No polymorphism was seen in DNA from the five minke whale samples, but Rsa I and Taq I restriction enzymes gave polymorphism in fin and sei whales whereas Hind III and Msp I restriction enzymes showed polymorphism in sei whales only. Only one bryde's whale sample was available for investigation. The study of DNA available from mother-fetus pairs from the two polymorphic species demonstrated a simple, two-allele transmission of RFLP alleles.     

Increased blubber cortisol in ice-entrapped beluga whales (<Emphasis Type="Italic">Delphinapterus</Emphasis><Emphasis Type="Italic">leucas</Emphasis>)

Entrapments of whales in sea ice occur occasionally in the Arctic and often last several weeks or months, resulting in emaciation or death of whales. These events provide a unique opportunity for investigating the physiological response to a prolonged or chronic stress in an otherwise healthy population of marine mammals. By measuring cortisol in blubber, a peripheral tissue, we expect to see a reflection of long-term or chronic stress rather than short-term or acute stress. Adipose tissue should be less subject to rapid changes compared to blood cortisol, reflecting stressors experienced over a longer period of time, and should not be affected by potential stress associated with sampling. We measured blubber cortisol of 29 beluga whales (Delphinapterus leucas) entrapped in November 2006 in Husky Lakes basin and 26 whales from the same population (Eastern Beaufort Sea) during regular seasonal harvests in July of 2006 and 2007. Mean cortisol concentrations (±SEM) were seven times higher in blubber from entrapped whales (1.76 ± 0.32 ng/g wet weight) compared to whales from regular seasonal harvests (0.26 ± 0.042 ng/g wet weight) and appeared to increase with whale age. Our results provide a measure of blubber cortisol from a prolonged stress and demonstrate blubber cortisol as a useful indicator of longer-term exposure to stress in beluga whales.     

Fight or flight: antipredator strategies of baleen whales

• 1 The significance of killer whale Orcinus orca predation on baleen whales (Mysticeti) has been a topic of considerable discussion and debate in recent years. Discourse has been constrained by poor understanding of predator‐prey dynamics, including the relative vulnerability of different mysticete species and age classes to killer whales and how these prey animals avoid predation. Here we provide an overview and analysis of predatory interactions between killer whales and mysticetes, with an emphasis on patterns of antipredator responses.
• 2 Responses of baleen whales to predatory advances and attacks by killer whales appear to fall into two distinct categories, which we term the fight and flight strategies. The fight strategy consists of active physical defence, including self‐defence by single individuals, defence of calves by their mothers and coordinated defence by groups of whales. It is documented for five mysticetes: southern right whale Eubalaena australis, North Atlantic right whale Eubalaena glacialis, bowhead whale Balaena mysticetus, humpback whale Megaptera novaeangliae and grey whale Eschrichtius robustus. The flight strategy consists of rapid (20–40 km/h) directional swimming away from killer whales and, if overtaken and attacked, individuals do little to defend themselves. This strategy is documented for six species in the genus Balaenoptera.
• 3 Many aspects of the life history, behaviour and morphology of mysticetes are consistent with their antipredator strategy, and we propose that evolution of these traits has been shaped by selection for reduced predation. Fight species tend to have robust body shapes and are slow but relatively manoeuvrable swimmers. They often calve or migrate in coastal areas where proximity to shallow water provides refuge and an advantage in defence. Most fight species have either callosities (rough and hardened patches of skin) or encrustations of barnacles on their bodies, which may serve (either primarily or secondarily) as weapons or armour for defence. Flight species have streamlined body shapes for high‐speed swimming and they can sustain speeds necessary to outrun pursuing killer whales (>15–20 km/h). These species tend to favour pelagic habitats and calving grounds where prolonged escape sprints from killer whales are possible.
• 4 The rarity of observed successful attacks by killer whales on baleen whales, especially adults, may be an indication of the effectiveness of these antipredator strategies. Baleen whales likely offer low profitability to killer whales, relative to some other marine mammal prey. High‐speed pursuit of flight species has a high energetic cost and a low probability of success while attacks on fight species can involve prolonged handling times and a risk of serious injury.

     

Whale killers: Prevalence and ecological implications of killer whale predation on humpback whale calves off Western Australia

Reports of killer whales (Orcinus orca) preying on large whales have been relatively rare, and the ecological significance of these attacks is controversial. Here we report on numerous observations of killer whales preying on neonate humpback whales (Megaptera novaeangliae) off Western Australia (WA) based on reports we compiled and our own observations. Attacking killer whales included at least 19 individuals from three stable social groupings in a highly connected local population; 22 separate attacks with known outcomes resulted in at least 14 (64%) kills of humpback calves. We satellite‐tagged an adult female killer whale and followed her group on the water for 20.3 h over six separate days. During that time, they attacked eight humpback calves, and from the seven known outcomes, at least three calves (43%) were killed. Overall, our observations suggest that humpback calves are a predictable, plentiful, and readily taken prey source for killer whales and scavenging sharks off WA for at least 5 mo/yr. Humpback “escorts” vigorously assisted mothers in protecting their calves from attacking killer whales (and a white shark, Carcharodon carcharias). This expands the purported role of escorts in humpback whale social interactions, although it is not clear how this behavior is adaptive for the escorts.