Alaska marine mammal stock assessments, 2005 (original) (raw)
Related papers
Population structure of North Pacific gray whales in light of trans‐Pacific movements
Marine Mammal Science, 2021
Recent findings that some gray whales that feed off Sakhalin Island (SI), Russia, in the western North Pacific (WNP) overwinter in the eastern North Pacific (ENP) indicate that population structure in this species is more complex than originally thought. We generated mitochondrial DNA (mtDNA) control region sequences and microsatellite genotypes (n = 12 loci) from 156 whales sampled off SI and compared them to available data from 106 ENP whales. Significant mitochondrial and nuclear genetic differentiation between the SI and ENP whales was found. Genetic cluster analysis identified two groups among the SI whales, one of which was genetically similar to ENP whales. Photographs collected from the biopsied SI whales showed that both groups comprised whales known to migrate to the ENP, suggesting that the clustering pattern was not reflective of some SI whales interbreeding while overwintering in the WNP. Instead, the genetic differentiation observed between the SI and ENP whales may be due to assortative mating of SI whales while west of eastern migratory routes. The rare but continued reports of gray whales off the coasts of Japan and China, however, confirm that some gray whales overwinter in the WNP and highlight the need to collect additional data from these whales.
Report of the 2006-2007 Census of the Eastern North Pacific Stock of Gray Whales
The southbound migration of the Eastern North Pacific stock of gray whales (Eschrichtius robustus) was documented by the National Marine Fisheries Service's Alaska Fisheries Science Center (AFSC) from 12 December 2006 to 22 February 2007. Research protocol was essentially identical to that used in previous surveys. This involved single observers independently searching for whales and recording data on environmental conditions and the time, location, count, and direction of travel for each sighting. The counting system and observer performance were tested through paired, independent observational effort. The timing of the 2006-2007 southbound migration seemed to be 1 week later than in previous years, with the median date close to 21 January instead of 15 January. Most (80%) of the sightings occurred in January, 17% were in February and only 3% were in December. Counts of gray whales pods during fair to excellent visibility conditions totalled 1,770 pods during the 73 days (651.6...
A Gray Area: On the Matter of Gray Whales in the Western North Pacific
Gray whales occur along the eastern and western margins of the North Pacific. While much is known about the biology and ecology of whales in the eastern North Pacific (ENP), until recently almost nothing was known about whales in the western North Pacific (WNP). In the ENP, gray whales migrate between wintering areas off Baja California, Mexico, to summer feeding areas in the Bering, Beaufort, and Chukchi Seas. In the WNP, gray whales feed during the summer in the Okhotsk Sea off northeast Sakhalin Island and off southeastern Kamchatka in the Bering Sea. During the winter, some gray whales observed feeding off Sakhalin and Kamchatka migrate to the west coast of North America, including Mexico, while others migrate to portions of the WNP off Asia. Genetic comparisons of ENP and WNP gray whales have found significant differences in both nuclear and mitochondrial DNA supporting their management as distinct population stocks. Whaling took a heavy toll on gray whales in both the western ...
Journal of Cetacean Research and Management
Gray whales (Eschrichtius robustus) occur along the eastern and western coastlines of the North Pacific as two geographically isolated populations and have traditionally been divided into the eastern (California-Chukchi) and western (Korean-Okhotsk) populations. Recent molecular comparisons confirm, based on differences in haplotypic frequencies, that these populations are genetically separated at the population-level. Both populations were commercially hunted, but only the eastern gray whale has returned to near pre-exploitation numbers. In contrast, the western population remains highly depleted, shows no apparent signs of recovery and its future survival remains uncertain. Research off Sakhalin Island, Russia between 1995 and 1999 has produced important new information on the present day conservation status of western gray whales and provided the basis for the World Conservation Union (IUCN) to list the population as 'Critically Endangered' in 2000. The information presented here, in combination with potential impacts from anthropogenic threats throughout the range of this population, raises strong concerns about the recovery and continued survival of the western gray whale.
New information on the gray whale migratory movements between the western and eastern North Pacific
International Whaling Commission, 2019
Gray whales have traditionally been considered to consist of two populations, one in the western North Pacific (WNP) and the other in the eastern North Pacific (ENP). The ENP population ranges from wintering areas off Baja California, Mexico, to summer feeding areas in the Bering, Beaufort, and Chukchi Seas. The WNP population feeds off Sakhalin Island and southeast Kamchatka, Russia. Historical evidence indicates that the South China Sea may have been used as a wintering ground in the WNP. Genetic, telemetry and photo-identification comparisons between the ENP and the WNP show some degree of population mixing during the winter. Here we present a multinational effort to evaluate trans-Pacific movements of gray whales identified in both the ENP and WNP. Images of 379 whales identified on the summer feeding grounds off Russia (316 from Sakhalin; 150 from Kamchatka), were compared to 10,685 individuals identified in the wintering lagoons of Baja California, Mexico (1,590 from Laguna Ojo de Liebre; 7,151 from Laguna San Ignacio; and 1,994 from Bahia Magdalena). A total of 43 matches were found, including: 14 Sakhalin-Kamchatka-Mexico, 25 Sakhalin-Mexico, and 4 Kamchatka-Mexico. These matches consist of 22 females, 13 males, and 8 whales of unknown sex. Thirteen whales were observed making round trips (summer-winter-summer), 11 with winter in Mexico and the following summer in Russia, and 6 with summer in Russia and the following winter in Mexico. The others were matched in non-sequential years. These 43 matches, in combination with 11 previous matches, result in 54 gray whales being linked between Russia and Mexico. Movements between the WNP and ENP represents 14.2% of gray whales identified off Sakhalin Island and Kamchatka, and the 0.5% of the gray whales identified in the breeding lagoon of the west coast of Baja California peninsula Mexico.
Assessment of genetic structure among eastern North Pacific gray whales on their feeding grounds
Marine Mammal Science, 2014
Although most eastern North Pacific (ENP) gray whales feed in the Bering, Beaufort, and Chukchi Seas during summer and fall, a small number of individuals, referred to as the Pacific Coast Feeding Group (PCFG), show intra-and interseasonal fidelity to feeding areas from northern California through southeastern Alaska. We used both mitochondrial DNA (mtDNA) and 12 microsatellite markers to assess whether stock structure exists among feeding grounds used by ENP gray whales. Significant mtDNA differentiation was found when samples representing the PCFG (n = 71) were compared with samples (n = 103) collected from animals feeding further north (F ST = 0.012, P = 0.0045). No significant nuclear differences were 1 Corresponding author (e-mail: aimee.lang@noaa.gov). 1 detected. These results indicate that matrilineal fidelity plays a role in creating structure among feeding grounds but suggests that individuals from different feeding areas may interbreed. Haplotype diversities were similar between strata (h PCFG = 0.945, h Northern = 0.952), which, in combination with the low level of mtDNA differentiation identified, suggested that some immigration into the PCFG could be occurring. These results are important in evaluating the management of ENP gray whales, especially in light of the Makah Tribe's proposal to resume whaling in an area of the Washington coast utilized by both PCFG and migrating whales.
Gray whale Eschrichtius robustus population and stock identity
Mammal Review, 2006
1. In response to conservation and management concerns about gray whale Eschrichtius robustus population and stock structure, we provide an overview of the life history and ecology of gray whales as a context for discussion of population and stock structure within the species. Historically eastern and western North Pacific gray whales were managed separately because: (i) their ranges do not overlap; (ii) genetic analyses indicate that the two populations are significantly different; and (iii) eastern gray whales have increased in abundance over the past century while western gray whales have not.
The western gray whale: a review of past exploitation, current status and potential threats
2002
Gray whales (Eschrichtius robustus) occur along the eastern and western coastlines of the North Pacific as two geographically isolated populations and have traditionally been divided into the eastern (California-Chukchi) and western (Korean-Okhotsk) populations. Recent molecular comparisons confirm, based on differences in haplotypic frequencies, that these populations are genetically separated at the population-level. Both populations were commercially hunted, but only the eastern gray whale has returned to near pre-exploitation numbers. In contrast, the western population remains highly depleted, shows no apparent signs of recovery and its future survival remains uncertain. Research off Sakhalin Island, Russia between 1995 and 1999 has produced important new information on the present day conservation status of western gray whales and provided the basis for the World Conservation Union (IUCN) to list the population as 'Critically Endangered' in 2000. The information presented here, in combination with potential impacts from anthropogenic threats throughout the range of this population, raises strong concerns about the recovery and continued survival of the western gray whale.