Parental behavior of the beluga whale (Delphinapterus leucas) in natural environment

The parental behavior of beluga whales observed in a summer reproductive gathering (near Solovetsky Island, Onega Bay, White Sea) is described, including the parturition process. A tight association between the female and its newborn infant has been traced by the case study of a stillborn calf. Individual behavioral patterns of a mother and calves observable only in natural habitats are detailed.     

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.     

Behavioral and acoustical characteristics of the reproductive gathering of beluga whales (Delphinapterus leucas) in the vicinity of Myagostrov, Golyi Sosnovets, and Roganka Islands (Onega Bay, the White Sea)

The structure of the summer reproductive gathering of beluga whales Delphinapterus leucas was studied in the vicinity of Myagostrov, Golyi Sosnovets, and Roganka islands (Onega Bay, the White Sea) in 2006 and 2008. The abundance, age and sex structure, behavior, and swimming and acoustic behavior were studied in detail.     

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.     

Long-term environmental impact of an oil spill in the southern part of Onega Bay,the White Sea

Complex studies were carried out in the southern part of Onega Bay (White Sea) in the summer seasons of 2003–2006 and 2011–2013. These studies revealed the dynamics of oil pollution of the water area after an accidental fuel oil spill in September 2003 and its long-term adverse effects on organisms of different trophic levels of the coastal ecosystem (benthos, fish, and sea mammal populations) in the most polluted southeastern part of the bay. The deterioration of the status of the top trophic-level white whale population (a decrease in numbers) and the accumulation of oil hydrocarbons in tissues of benthic organisms are described.     

Population structure of North American beluga whales (Delphinapterus leucas) based on nuclear DNA microsatellite variation and contrasted with the population structure revealed by mitochondrial DNA variation

Beluga whales ( Delphinapterus leucas ) in North American waters migrate seasonally between wintering areas in broken pack ice and summering locations in estuaries and other open water areas in the Arctic and sub-Arctic. Results from our previous investigation of beluga whale mitochondrial DNA (mtDNA) revealed genetic heterogeneity among beluga from different summering locations that was interpreted as representing a high degree of summering site philopatry. However, mtDNA is maternally inherited and does not reflect mating that may occur among beluga from different summering locations in wintering areas or during annual migrations. To test the possibility that breeding occurs among beluga from different summering locations, genetic variability at five nuclear DNA (nDNA) microsatellite loci was examined in the same animals tested in the mtDNA study. Beluga samples ( n = 640) were collected between 1984 and 1994 from 24 sites across North America, mostly during the summer. Whales from the various sites were categorized into eight summering locations as identified by mtDNA analysis, as well as four hypothesized wintering areas: Bering Sea, Hudson Strait (Hudson Strait, Labrador Sea, southwest Davis Strait), Baffin Bay (North Water, east Davis Strait), and St Lawrence River. Microsatellite allele frequencies indicated genetic homogeneity among animals from summering sites believed to winter together but differentiation among whales from some of the wintering areas. In particular, beluga from western North America (Bering Sea) were clearly distinguished from beluga from eastern North America (Hudson Strait, Baffin Bay, and St Lawrence River). Based upon the combined data set, the population of North American beluga whales was divided into two evolutionarily significant units. However, the population may be further subdivided into management units to reflect distinct groups of beluga at summering locations.     

Population structure of North American beluga whales (Delphinapterus leucas) based on nuclear DNA microsatellite variation and contrasted with the population structure revealed by mitochondrial DNA variation

Beluga whales ( Delphinapterus leucas ) in North American waters migrate seasonally between wintering areas in broken pack ice and summering locations in estuaries and other open water areas in the Arctic and sub-Arctic. Results from our previous investigation of beluga whale mitochondrial DNA (mtDNA) revealed genetic heterogeneity among beluga from different summering locations that was interpreted as representing a high degree of summering site philopatry. However, mtDNA is maternally inherited and does not reflect mating that may occur among beluga from different summering locations in wintering areas or during annual migrations. To test the possibility that breeding occurs among beluga from different summering locations, genetic variability at five nuclear DNA (nDNA) microsatellite loci was examined in the same animals tested in the mtDNA study. Beluga samples ( n = 640) were collected between 1984 and 1994 from 24 sites across North America, mostly during the summer. Whales from the various sites were categorized into eight summering locations as identified by mtDNA analysis, as well as four hypothesized wintering areas: Bering Sea, Hudson Strait (Hudson Strait, Labrador Sea, southwest Davis Strait), Baffin Bay (North Water, east Davis Strait), and St Lawrence River. Microsatellite allele frequencies indicated genetic homogeneity among animals from summering sites believed to winter together but differentiation among whales from some of the wintering areas. In particular, beluga from western North America (Bering Sea) were clearly distinguished from beluga from eastern North America (Hudson Strait, Baffin Bay, and St Lawrence River). Based upon the combined data set, the population of North American beluga whales was divided into two evolutionarily significant units. However, the population may be further subdivided into management units to reflect distinct groups of beluga at summering locations.     

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.     

Long-term social structure of long-finned pilot whales (<Emphasis Type="Italic">Globicephala melas</Emphasis>) in the Strait of Gibraltar

The Strait of Gibraltar is inhabited by around 216 pilot whales, which are present all year round, and nothing is known about their social structure. The aim of this study is to analyse the inter-individual association patterns within this pilot whales community to (1) provide an insight on their long-term social system and (2) to assess the relationship between sexes within this social system. Between 1999 and 2006, 23,004 km was sampled in the Strait of Gibraltar, and 4,887 images of dorsal fins of pilot whales were taken from 226 groups. The sex of 56 of the individuals could be determined genetically. The strength of the behavioural relationships between dyads of individuals was calculated, and the temporal aspects of the social structure were evaluated, showing in a non-random social structure made by constant companions. The preferred associations between individuals consisted in associations of males–females. Eight long-term units could be found with different degrees of association rates. Consequently, we propose that, in the Strait, the pilot whales exhibit a hierarchical social system composed of a population encompassing several clans of pilot whales each containing several pods. Pods will then be formed by several line units, similar to killer whale matrilineal units.     

Residency and abundance of sperm whales (Physeter macrocephalus) in Nemuro Strait,Hokkaido, Japan

We examined the trend in residence patterns and abundance of male sperm whales in Nemuro Strait, Japan, based on long-term photo-identification (1,513 survey days, total 2,969 photos) between 2006 and 2017. A total of 225 unique individuals were identified during this study, with an average of 36 (SE = 2.55) new individuals identified in each season. The model chosen by maximum likelihood suggests that residence time around Nemuro Strait is 769 (SE = 372.4) days, with individuals staying in the strait about 48 days (SE = 8.36) per year. While the migration patterns of male sperm whales visiting this area are still unclear, these findings along with previous studies suggest that males move from one breeding area to another neighboring area every several weeks, shifting their home ranges gradually over a period of a few years. The abundance of sperm whales in Nemuro Strait varied greatly from year to year; from 28 (95%CI: 24–44) in 2015 and (95%CI: 22–48) in 2016 to 66 (95%CI: 57–84) in 2011. This study provides important knowledge of abundance and residency for Nemuro Strait, information which will contribute to further research on the social structure and movement pattern of male sperm whales.     

Humpback whales (Megaptera novaeangliae) attend both Mexico and Hawaii breeding grounds in the same winter: mixing in the northeast Pacific

Humpback whales that assemble on winter breeding grounds in Mexico and Hawaii have been presumed to be, at least, seasonally isolated. Recently, these assemblies were declared Distinct Population Segments under the US Endangered Species Act. We report two humpback whales attending both breeding grounds in the same season—one moving from Hawaii to Mexico and the other from Mexico to Hawaii. The first was photo-identified in Maui, Hawaii on 23 February 2006 and again, after 53 days and 4545 km, on 17 April 2006 in the Revillagigedo Archipelago, Mexico. The second was photo-identified off Guerrero, Mexico on 16 February 2018 and again, 49 days and 5944 km later, on 6 April 2018 off Maui. The 2006 whale was identified in summer off Kodiak Island, Alaska; the 2018 whale off British Columbia. These Mexico–Hawaii identifications provide definitive evidence that whales in these two winter assemblies may mix during one winter season. This, combined with other lines of evidence on Mexico–Hawaii mixing, including interchange of individuals year to year, long-term similarity of everchanging songs, one earlier same-season travel record, and detection of humpback whales mid-ocean between these locations in winter, suggests reassessment of the ‘distinctiveness'' of these populations may be warranted.     

Satellite telemetry reveals population specific winter ranges of beluga whales in the Bering Sea

At least five populations (stocks) of beluga whales (Delphinapterus leucas) are thought to winter in the Being Sea, including the Bristol Bay, Eastern Bering Sea (Norton Sound), Anadyr, Eastern Chukchi Sea, and Eastern Beaufort Sea (Mackenzie) populations. Belugas from each population have been tagged with satellite‐linked transmitters, allowing us to describe their winter (January–March) distribution. The objectives of this paper were to determine: (1) If each population winters in the Bering Sea, and if so, where? (2) Do populations return to the same area each year (i.e., are wintering areas traditional)? (3) To what extent do the winter ranges of different populations overlap? Tagged belugas from all five populations either remained in, or moved into, the Bering Sea and spent the winter there. Each population wintered in a different part of the Bering Sea and populations with multiple years of data (four of five) returned to the same regions in multiple years. When data were available from two populations that overlapped in the same year, they did not occupy the shared area at the same time. Although our sample sizes were small, the evidence suggests belugas from different populations have traditional winter ranges that are mostly exclusive to each population.     

Phenological changes in North Atlantic right whale habitat use in Massachusetts Bay

The North Atlantic right whale (Eubalaena glacialis) is one of the world's most highly endangered baleen whales, with approximately 400–450 individuals remaining. Massachusetts Bay (MB) and Cape Cod Bay (CCB) together comprise one of seven areas in the Gulf of Maine where right whales seasonally congregate. Here, we report on acoustically detected presence of right whales in MB over a nearly 6 year period, July 2007–April 2013, a time of both rapid ocean warming throughout the Gulf of Maine and apparent changes in right whale migratory dynamics. We applied an automated detection algorithm to assess hourly presence of right whale “up‐calls” in recordings from a 19‐channel acoustic array covering approximately 4,000 km² in MB. Over the survey, up‐calls were detected in 95% of 8 day periods. In each year, as expected, we observed a “peak season” of elevated up‐call detections in late winter and early spring corresponding to the season when right whales congregate to feed in CCB. However, we also saw an increase in right whale occurrence during time periods thought to be part of the “off‐season.” With the exception of 2009–2010, when acoustic presence was unusually low, the mean percent of hours in which up‐calls were detected increased every year, both during the peak season (from 38% in 2008 to 70% in 2012), and during the summer–fall season (from 2% in 2007 to 13% in 2012). Over the entire study, the peak season start date varied between 17 January and 26 February. Changes in right whale phenology in MB likely reflect broadscale changes in habitat use in other areas within the species range. This study demonstrates the value of continuous long‐term survey datasets to detect and quantify shifts in cetacean habitat use as environmental conditions change and the long‐term continued survival of right whales remains uncertain.     

Some population dynamics of the Bank vole, Clethrionomys glareolus and the Wood mouse, Apodemus sylvaticus in mixed woodland

The population dynamics of Clethrionomys glareolus Schr.and Apodemus sylvaticus (L.) in mixed woodland in County Durham, were studied from March 1963 to January 1965. Two areas of 0.9 ha (2.25 acres) each were trapped monthly and information was obtained on population size, reproduction, survival and growth from marked animals.
Clethrionomys populations increased from June to an autumn peak; then declined, at first rapidly, but then more slowly in winter, before reaching a spring trough. The breeding season of Clethrionomys was from May to December; juveniles were caught from mid-June to December. Survival was in general poor during the breeding season but good at other times. Survival of young born early in the summer was particularly good on one of the areas and some individuals lived long enough to breed in two successive years. On both areas young born early in the year matured rapidly and bred in the year of their birth. Young born in late summer and early autumn ceased growing at a weight of about 14.5 g, remained immature, and formed the bulk of the overwintering population. Growth was completed at the time of sexual maturation the following spring.
Trapping failed to provide adequate samples of juvenile Apodemus in summer to account for subsequent recruitment. The possibility that a substantial proportion of the adult population of this species was also either trap shy or had emigrated temporarily is discussed. Breeding occurred from April until the following January, but the numbers trapped remained very low throughout the early months of the breeding season. Large scale recruitment of young fecund animals into the trap-revealed population occurred during the autumn. Apodemus males continued to grow rapidly during the winter.     

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.     

An analysis of sightings of Cetacea in British waters

An analysis is carried out of all documented sightings of cetaceans in British waters between 1950–1975, received by the Cetacean Group. Two major problems which must be taken into account in such an analysis are difficulties of specific identification and bias from uneven coverage.
The results show that porpoises are present in coastal waters for much of the year. The pattern of movements for this species is rather confused. Most dolphin species show peak numbers in summer, earliest in the north of Britain and later further south. Risso's dolphins may enter British waters rather earlier in spring than other species. Killer whales occur off the west coast of Britain and Ireland mainly between June-September. Pilot whales are seen in North Britain at most times of the year but otherwise enter British waters along the west coast in spring. Bottle-nosed whales and the larger whale species, including the Rorquals, are found only on the north and west coasts in summer and early autumn. For all species, herd size increases at the same time as increase in the numbers of sightings reported. Different species have different herd sizes with the largest occurring amongst porpoise and all dolphin species except Risso's dolphin, and the smallest amongst the large whale species. Herds may be accompanied by young individuals in spring-late summer, depending on the species.     

Occurrence of dwarf minke whales (Balaenoptera acutorostrata subsp.) around the Antarctic Peninsula

The occurrence of dwarf minke whales (Balaenoptera acutorostrata subsp.) around the Antarctic Peninsula was examined based on 406 sightings of minke whales recorded during the Chilean Antarctic Scientific Expeditions and other opportunistic cetacean surveys. Identification of the species was made only for the whales sighted in the proximity of the vessels when the specific diagnostic characters could be confirmed. Of the 406 sightings, 296 were assigned to Antarctic (519 individuals), nine (11 individuals) to dwarf and 101 to unidentified minke whales (149 individuals). Dwarf minke whales were identified by the reported external diagnostic characters for this species. Seven animals occurred around the South Shetland Island and four in the Gerlache Strait. In addition, another two animals were identified as dwarf minke whales in the Bellinghausen Sea in winter 1993, being these the most southern records for this species. These results confirm the occurrence of dwarf minke whales around the Antarctic Peninsula during the summer seasons, as well as in the Bellinghausen Sea in winter. The geographical range of these sightings was comprised between 61°03′ and 69°25′S and between 55°29′ and 86°53′W. These results also suggest that some dwarf minke whales remain in the Antarctic during the austral winter.     

SITE FIDELITY, ASSOCIATIONS, AND MOVEMENTS OF CUVIER'S (ZIPHIUS CAVIROSTRIS) AND BLAINVILLE'S (MESOPLODON DENSIROSTRIS) BEAKED WHALES OFF THE ISLAND OF HAWAI'I

Although the Ziphiidae are the second-most speciose family of cetaceans, information on beaked whale species and populations has been limited by the difficulties in finding and approaching free-ranging individuals. Site fidelity, patterns of association, and movements of two species, Cuvier's ( Ziphius cavirostris ) and Blainville's ( Mesoplodon densirostris ) beaked whales, were assessed using a 21-yr photographic data set from the west coast of the island of Hawai i. Resightings of individuals of both species spanned 15 yr, suggesting long-term site fidelity to the area. Long-term resightings were documented primarily from adult females of both species. Group sizes for both species were small and most groups had only a single adult male present. For Blainville's beaked whales, repeated associations between adult females and adult males were documented for all resightings of adult males over periods from 1 to 154 d. Among adult females, although repeated associations occurred up to 9 yr apart, individuals were seen separately in intervening years. Individuals of both species seen on multiple occasions were typically documented in multiple months/seasons, suggesting they may use the study area throughout the year. Such long-term site fidelity has implications both for potential population structure and for susceptibility of beaked whale populations to anthropogenic impacts.     

Key Factors Determining the Distribution of Beluga Whales, <Emphasis Type="Italic">Delphinapterus leucas</Emphasis> (Pallas, 1776), in River Estuaries of Western Kamchatka

The results of observations on the distribution of beluga whales, Delphinapterus leucas (Pallas, 1776), in three large rivers of western Kamchatka in the summer and autumn seasons are discussed. In the summer, the number of beluga whales in the Khairyuzova, Belogolovaya, and Moroshechnaya rivers reaches 111–250 individuals. Most of the belugas enter the rivers during the flood tidal phase: the number of animals in the estuaries increases along with the rising water level to the maximum value at spring tide. The belugas do not move upstream out of the estuaries and tend to remain in the zone of mixing riverine and marine waters, where 20 species of fish and three species of invertebrates have been identified. At ebb tide, the belugas leave for the sea; however, during a large run of salmon some individuals remain in the estuaries and continue hunting in deep-water areas. The main issue that causes beluga whales to form summer aggregations in Kamchatkan rivers is the hunt for salmon. The distribution of beluga whales in river estuaries is defined by the dynamics and intensity of salmon spawning runs. The preference of beluga whales for these rivers can be explained by the channel type of their estuaries.     

The reproductive cycle and life history of the Arctic copepod Calanus glacialis in the White Sea

Seasonal variations in the gonad development and sex ratio of copepodite stage V (CV) and adults were examined from February to November in order to understand the reproductive cycle and the life history of Calanus glacialis in the White Sea. Gonad maturation, sexual differentiation and moulting to adults take place during the 2nd year of development. Energy accumulation takes place in the spring and summer of the 2nd year. The following autumn/winter is the major period of CV maturation, which occurs independent of food supply. Maturation of males precedes that of females by 2–3 months. The maximum proportions of CV and adult males are found in the population in October and November. The onset of female maturation is observed in February and March, ca. 2 months prior to the spring phytoplankton bloom. Reproduction takes place between April and June. Its termination in the second half of June coincides with the warming of the surface water layer where egg laying takes place. Variations in the gonad morphology throughout the year suggest long life spans and iteroparity of females of C. glacialis in the White Sea. Many of them survive for several months after reproduction and are able to overwinter again. Therefore, females with different life histories co-occur in the population in winter: “young” females recently moulted from the overwintering CVs, and “old” females which have spawned at least once in their life, after which they return to overwintering conditions. In contrast, males have shorter life spans of 3–4 months resulting in a sex ratio skewed toward females at all seasons. Accepted: 27 April 1999