Summer molting of bowhead whales <Emphasis Type="Italic">Balaena mysticetus</Emphasis> Linnaeus, 1758, of the Okhotsk Sea population

In bowhead whales summering in Ulbanskiy Bay of the Okhotsk Sea, molting of epidermis has been found and histologically confirmed. The outer layer of the molting whale epidermis is longitudinally stratified and rejected in the form of relatively large plates up to several millimeters thick, each representing a lamellar formation consisting of longitudinal rows of parakeratocytes with degenerated nuclei, numerous pigment granules, and lipid inclusions. Molting intensity is correlated with the level of proliferation and regeneration of all epidermal layers, which helps to maintain the optimal skin thickness.     

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.     

New Data About Seasonal Distribution and Migrations of Whales and Dolphins in the Sea of Okhotsk

This paper presents new data about the seasonal distribution of whales and dolphins in the Sea of Okhotsk including the ice period. Even under the most severe ice conditions, the migrating species of whales and dolphins may be encountered in the Sea of Okhotsk. In all seasons the density of cetaceans is higher in the eastern part of the sea, which is more abundant in fish.     

Status of the world's baleen whales

No global synthesis of the status of baleen whales has been published since the 2008 IUCN Red List assessments. Many populations remain at low numbers from historical commercial whaling, which had ceased for all but a few by 1989. Fishing gear entanglement and ship strikes are the most severe current threats. The acute and long‐term effects of anthropogenic noise and the cumulative effects of multiple stressors are of concern but poorly understood. The looming consequences of climate change and ocean acidification remain difficult to characterize. North Atlantic and North Pacific right whales are among the species listed as Endangered. Southern right, bowhead, and gray whales have been assessed as Least Concern but some subpopulations of these species ‐ western North Pacific gray whales, Chile‐Peru right whales, and Svalbard/Barents Sea and Sea of Okhotsk bowhead whales ‐ remain at low levels and are either Endangered or Critically Endangered. Eastern North Pacific blue whales have reportedly recovered, but Antarctic blue whales remain at about 1% of pre‐exploitation levels. Small isolated subspecies or subpopulations, such as northern Indian Ocean blue whales, Arabian Sea humpback whales, and Mediterranean Sea fin whales are threatened while most subpopulations of sei, Bryde's, and Omura's whales are inadequately monitored and difficult to assess.     

Abundance estimate of the Okhotsk Sea population of the bowhead whale (<Emphasis Type="Italic">Balaena mysticetus</Emphasis> Linnaeus, 1758)

Abundance of 388 ± 108 whales for the Okhotsk Sea bowhead whale population based on individual genotyping was estimated using the capture–recapture method for the open population model. The data demonstrate that this endangered population shows no signs of recovery.     

Molecular genetic study of the beluga (<Emphasis Type="Italic">Delphinapterus leucas</Emphasis>: Cetacea,Monodontidae) summering in the southern Sea of Okhotsk as compared to North American populations

The structure of the left part of the mtDNA control region has been studied in Delphinapterus leucas captured in summer in the southern Sea of Okhotsk. The data have been compared with published results of similar studies on D. leucas at different sites along the American coast. A high specificity of maternal lineages of D. leucas from the southern Sea of Okhotsk has been demonstrated against the background of its historical connection with the form from the Pacific refugium that colonized the western Arctic region in postglacial time.     

Some biological features and productive characteristics of <Emphasis Type="Italic">Oithona similis</Emphasis> (Copepoda) in the Sea of Okhotsk and western Bering Sea

The biological peculiarities of Oithona similis were described based on the materials from 29 complex surveys that were conducted by the TINRO Center in the Sea of Okhotsk and the western Bering Sea from 1986 to 2005 and the production of the species was estimated. In this area, O. similis produces four generations a year, viz., one in the spring, one in the fall, and two in the summer. The peak of spawning in May and June coincides with the maximum development of phytoplankton. Somatic production of O. similis in both seas becomes higher during the summer season. In this species, the largest increment in body weight begins with the copepodite stage CIV, when basic nutrients are accumulated. The average specific daily production of O. similis in the epipelagic zone of the Sea of Okhotsk and Bering Sea was 0.0092 and 0.01 in the spring, 0.043 and 0.031 in the summer, and 0.023 and 0.014 in the fall, respectively. The total somatic production of this species reached 28.318 million tons in the Sea of Okhotsk and 4.811 million tons in the Bering Sea. The Sea of Okhotsk is more favorable for the development of O. similis.     

The distribution of zooplankton and bowhead whales, <Emphasis Type="Italic">Balaena mysticetus</Emphasis> Linnaeus, 1758, in Akademiya Bay,Sea of Okhotsk

The modern pattern of distribution and feeding habits of the bowhead whale, Balaena mysticetus, in the Sea of Okhotsk are studied. The existence of a feeding aggregation of this whale species in the southwesternmost portion (apex) of Ulban Bay has been confirmed. There, the animals feed in shallow waters with depths of 3–5 m, which are only slightly larger than their body height. The quantitative composition and species structure of zooplankton at the stations that were set near feeding whales have been analyzed. In the samples taken in the immediate proximity to the feeding whales, the abundance of zooplankton reached 31409 ind./m³, with the average value of 17565 ind./m³. The lowest abundance, from 56 to 1879 ind./m³ (mean 927 ind./m³), was in the samples from western Konstantin Bay, where bowhead whales were not observed. In 16 samples collected in the immediate proximity to the feeding whales in the shallow waters of Ulban Bay, the average zooplankton biomass was 547.9 mg/m³, which is 3.9 times higher than that in the samples from waters where the whales were absent. Copepods dominated quantitatively at all the stations in Akademiya Bay. The proportion of euphausiids in the zooplankton biomass was lower than 1%, both near the feeding whales and in the absence of whales.     

Presence and behavior of bowhead whales (Balaena mysticetus) in the Alaskan Beaufort Sea in July 2011

The Western Arctic bowhead whale (Balaena mysticetus) is highly adapted to sea ice and annually migrates through the Bering, Chukchi, and Beaufort seas. While the overall distribution and seasonal movements of bowhead whales are mostly understood, information about their distribution in the Alaskan Beaufort Sea in early to mid-summer has not been well documented. In July 2011, we conducted an exploratory flight in the Alaskan Beaufort Sea, north of Camden Bay (71°N 144°W), near the location of a single satellite-tagged bowhead whale. Eighteen bowhead whales were observed, and behavior consistent with feeding was documented. To our knowledge, this is the first documentation of behavior consistent with feeding north of Camden Bay in mid-July. Few studies have focused on bowhead whale distribution in the Alaskan Beaufort Sea in early to mid-summer, and no long-term, region-wide surveys have been conducted during summer. Bowhead whales are already exposed to anthropogenic disturbance in the Canadian Beaufort Sea in summer, the Alaskan Beaufort Sea in fall, and the Chukchi and Bering seas from fall through spring. The presence of bowhead whale aggregations in the Alaskan Beaufort Sea in summer should be considered when assessing the cumulative effects of human-related activities.     

Seasonal migrations of Sea of Okhotsk beluga whales (<Emphasis Type="Italic">Delphinapterus leucas</Emphasis>) of the Sakhalin-Amur summer aggregation

Seasonal migrations of beluga whales from the Sakhalin-Amur aggregation in the Sea of Okhotsk were investigated with the use of satellite telemetry. Satellite tags were attached to four females captured near Chkalova Island, Sakhalin Bay, in August 2007. At 5 weeks after tagging, the belugas left the Chkalova Island area and moved to the Nikolaya and Ul’banskii Bays in the Shantar Sea. The animals stayed in these bays (mainly in Nikolaya Bay) until the end of autumn and then traveled northward to deeper waters. In winter and spring, they preferred to stay in the regions with dense ice cover or close to the ice edge. During the winter migration, the tagged whales, as a rule, did not keep together, although they followed the same course with a little time lag. The female whose tag transmitted the longest (9.5 months) returned to Chkalova Island in late May and thus completed the seasonal migration cycle. Based on the data on the migration routes of the tagged belugas, we suggest that the Sakhalin-Amur and Shantar aggregations interact in autumn. It is also possible that they have similar winter migratory paths     

Origin of juvenile chum salmon <Emphasis Type="Italic">Oncorhynchus keta</Emphasis> (Salmonidae) in the Sea of Okhotsk coastal waters off South Sakhalin

Based on the data of the analysis of distribution of juvenile chum salmon Oncorhynchus keta that were marked at salmon hatcheries in the southern part of the Sakhalin Island and Japan it has been established that their stocks in the Sea of Okhotsk coastal waters off South Sakhalin and Japan are of mixed origin. One part of the stock is composed of juveniles from hatcheries located in the southern part of Sakhalin, and the other part is composed of migrants from the waters adjacent to Japan. The first part is formed by juveniles both from hatcheries on the Sea of Okhotsk and Sea of Japan coasts of South Sakhalin. The second part is formed by juveniles reared at hatcheries in all regions of Japan: the Pacific and Sea of Okhotsk coasts of Honshu and Hokkaido, and from the Sea of Okhotsk coast of Hokkaido and Izmena (Nemuro) Strait. In July, in the Sea of Okhotsk coastal waters off South Sakhalin, the length and weight of most juvenile chum salmon of Japanese origin exceed 10 cm and 10 g, and juveniles of Sakhalin origin are always smaller than 10 cm and 10 g, which makes it possible to differentiate juveniles in trawl catches.     

Molecular genetic study of the beluga (Delphinapterus leucas: Cetacea, Monodontidae) summering in the southern Sea of Okhotsk as compared to North American populations

The structure of the left part of the mtDNA control region has been studied in Delphinapterus leucas captured in summer in the southern Sea of Okhotsk. The data have been compared with published results of similar studies on D. leucas at different sites along the American coast. A high specificity of maternal lineages of D. leucas from the southern Sea of Ok.     

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.     

Status,number, and monitoring of the common eider (<Emphasis Type="Italic">Somateria mollissima</Emphasis>) population in the barents sea and the White Sea

The breeding, molting, and wintering ranges of the common eider (Somateria mollissima) were mapped and described in the southern part of the Barents Sea region, including the White Sea population in the western White Sea and the Murmansk population in the northwestern White Sea and the southeastern Barents Sea. The present-day abundance was determined for both populations: since the 1950s, it was the highest in the 2000s for the entire period of ornithological monitoring in the region. Aerial survey from a helicopter is considered to be the only reliable method for estimation of the total population number. The best season for surveying the White Sea population is March–early April (wintering); the most favorable period for surveying the Murmansk population is August (postbreeding/molting). The population status of the common eider in the northern and eastern parts of the Barents Sea has not yet been evaluated. On Franz-Josef Land, the common eider is distributed sporadically, and its number was assessed using expert estimates. The current abundance of the common eider on Novaya Zemlya is unknown. Helicopter-based aerial survey performed in late summer during the postbreeding season is the only relevant method to obtain reliable estimates for the population of the common eider inhabiting Franz-Josef Land and Novaya Zemlya.     

Intraspecific variability in the “vowel”‐like sounds of beluga whales (Delphinapterus leucas): Intra‐ and interpopulation comparisons

The beluga whale (Delphinapterus leucas) has a rich and complicated vocal repertoire. However, different populations use similar and common types of signals. We studied physical features of one of these types, “vowels,” in three Russian populations: the White Sea population (European North), the Chukotka population (the Bering Sea, Chukotka), and the Okhotsk Sea population (Russian Far East) as well as in four summer aggregations of the White Sea belugas over several years in duration. The pulse repetition rate (PRR) at half of the duration of the signal was measured. We found that the PRR of “vowels” collected in the same summer aggregation during different years is stable in time but varies between locations. The degree of variation corresponds with the geographic distance between different locations. Significant differences were discovered between populations separated by thousands of kilometers, and to a lesser extent, between summer aggregations inhabiting different bays of the White Sea. The variation in PRR between the locations can be caused by the divergence of signals owing to the accumulation of random errors during transmission of these signals from generation to generation, which progressed independently in different summer aggregations and populations.     

Specific Biological Traits of Males of the Blue Crab Paralithodes platypusin the Northeast Part of the Sea of Okhotsk

Data on body size, composition, and mass; peculiarities of molting; and number and seasonal migrations of males of the blue king crab Paralithodes platypusfrom the northeast part of the Sea of Okhotsk are presented. It was found that the main aggregations of juveniles (up to 65% of the total number) are located in the south of the population area. Males molt once every two years, and the relative number of groups molting in alterating years was equal. Mass molting was observed at the end of June and July. Mass migration of males to shoals occurred in June, and their return occurred in October.     

DIETS OF BAIRD'S BEAKED WHALES, BERARDIUS BAIRDII, IN THE SOUTHERN SEA OF OKHOTSK AND OFF THE PACIFIC COAST OF HONSHU, JAPAN

Stomach contents were analyzed from 127 Baird's beaked whales, Berardius bairdii , taken in coastal waters of Japan. During late July-August of 1985–1987, 1989, and 1991, 107 samples were collected from off the Pacific coast of Honshu. An additional 20 samples were collected from whales taken in the southern Sea of Okhotsk during late August—September of 1988 and 1989. Prey identification using fish otoliths and cephalopod beaks revealed the whales fed primarily on deep-water gadiform fishes and cephalopods in both regions. Prey species diversity and the percentage of cephalopods and fish differed between the two regions. Off the Pacific coast of Honshu the whales fed primarily on benthopelagic fishes (81.8%) and only 18.0% on cephalopods. Eight species of fish representing two families, the codlings (Moridae) and the grenadiers (Macrouridae), collectively made up 81.3% of rhe rotal. Thirty species of cephalopods representing 14 families made up 12.7%. In the southern Sea of Okhotsk, cephalopods accounted for 87.1% of stomach contents. The families Gonatidae and Cranchiidae were the predominant cephalopod prey, accounting for 86.7% of the diet. Gadiform fish accounted for only 12.9% of the diet. Longfin codling, Laemonema longipes , was the dominant fish prey in both regions. Depth distribution of the two commonly consumed fish off the Pacific coast of Honshu indicate the whales in this region fed primarily at depths ranging from 800 to 1,200 m.     

SEGREGATIVE MIGRATION OF DALL'S PORPOISE (PHOCOENOIDES DALLI) IN THE SEA OF JAPAN AND SEA OF OKHOTSK

Dall's porpoises from the Sea of Japan population taken by a dolphin fishery vessel were examined. Estimated body lengths at sexual maturity were similar to those for the truei -type population off the Pacific coast of Japan but larger than those for the offshore dalli -type in the North Pacific. The Sea of Japan population is known to migrate to the Pacific coast of Japan through Tsugaru Strait and to the Sea of Okhotsk through Soya Strait in summer. From the difference of catch composition, individuals of different reproductive status in this population are considered to have different patterns of summer migration. Most of the individuals which migrate into the Pacific Ocean through Tsugaru Strait are sexually immature, while those migrating into the Sea of Okhotsk are mature. The Sea of Okhotsk is thought to be a breeding area for this population. The calving season is estimated to be May through June, which is earlier than that of the truei -type off the Pacific coast of northern Japan. This may be an adaptation to lower water temperatures in the Sea of Japan during winter.     

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.     

The Adaptive Behavior of the White Whales <Emphasis Type="Italic">Delphinapterus leucas</Emphasis> (Pallas, 1776) in the Southern Herd of the White Sea under Conditions of the Local Habitat During the Breeding Season

Research on a southern herd of white (beluga) whales conducted during the summer seasons of 2003–2006 in the southeastern part of the Onega Bay revealed the specific behavioral features that allow white whales to sustain their habitation in the local hydrological conditions. It has been shown that once the white whales occur in some areas of habitation with complicated hydrological conditions, the animals develop an entire complex of behavioral adaptations that provide their comfort and their successful reproduction in the habitat.