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Reliable estimates of population abundance and demographics are essential for managing harvested species. Ice‐associated phocids, "ice seals," are a vital resource for subsistence‐dependent coastal Native communities in western and northern Alaska, USA. In 2012, the Beringia distinct population segment of the bearded seal, Erignathus barbatus nauticus, was listed as "threatened" under the US Endangered Species Act requiring greater scrutiny for management assessments. We sought to estimate requisite population parameters from harvested seals by using close‐kin mark‐recapture (CKMR) methods, the first such application for marine mammals. Samples from 1758 bearded seals harvested by Bering, Chukchi, and Beaufort Sea communities during 1998–2020 were genotyped, genetically sexed, and aged by tooth annuli. After rigorous quality control, kin relationships were established for 1484 seals including two parent–offspring pairs (POPs) and 25 potential second‐order kin pairs. Most of the second‐order kin were half‐sibling pairs (HSPs), but four were potential grandparent‐grandchild pairs (GGPs). There were no full sibling pairs, suggesting a lack of mate fidelity. Mitochondrial DNA analysis identified 17 potential HSPs as paternally related, providing substantial evidence of persistent heterogeneity in reproductive success among adult males. The statistical CKMR model incorporates probabilities associated with POPs, HSPs, and GGPs and assumes known ages and a stable population. Our top model accommodates heterogeneity in adult male breeding success and yields an abundance estimate of ~409,000 with a coefficient of variation (CV) = 0.35, which is substantially greater than the "non‐heterogeneity" model estimate of ~232,000 (CV = 0.21), an important difference for managing a harvested species. Using CKMR methods with harvested species provides estimates of abundance with the added opportunity to acquire information about adult survival, fecundity, and breeding success that could be applied to other species of concern, marine and terrestrial. [ABSTRACT FROM AUTHOR]

Photographic and genetic studies have revealed the complex population structure of migratory large whales. Most research and management are geographically based, focusing on either wintering or summering areas, which in most cases fails to capture this complexity. We use examples from humpback whales (Megaptera novaeangliae) and gray whales (Eschrichtius robustus) to illustrate the concept of migratory herds, defined here as conspecific whales that migrate between the same wintering and feeding ground. In cases where individuals show strong fidelity to both feeding and wintering grounds, and therefore to a herd, dispersal between herds can be low enough to render them as demographically independent populations, where population dynamics are determined more by net internal recruitment (births minus deaths) than by immigration from outside sources. In these cases, the migratory whale herd is the appropriate unit to conserve under the ecological paradigm that focuses on groups united by demographic forces. We suggest that when addressing questions focused on ecological timescales for whale species with strong fidelity to migratory destinations, the migratory whale herd is a better initial working hypothesis rather than one based on geographically defined strata. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Boat-based photo-identification research has been carried out on bottlenose dolphins in eastern North Pacific coastal waters off northern Baja California, Mexico and southern and central California, USA from 1981 to 2001. Within these waters, bottlenose dolphins routinely travel back and forth between coastal locations while generally staying within a narrow corridor extending only 1-2 km from the shore. Inter-area match rates for 616 dolphins photo-identified between 1981-2000 in four California coastal study areas (CCSAs) of Ensenada, San Diego, Orange County and Santa Barbara averaged 76%. To explore possible southern range limits for these dolphins, photo-identification surveys were carried out in the coastal waters off San Quintín, Baja California, Mexico between April-August 1990 ( n = 8 surveys) and July 1999 to June 2000 ( n = 12 surveys). The 207 individual dolphins identified off San Quintín were compared to the 616 dolphins identified in the CCSAs. The inter-area match rate between San Quintín and the CCSAs was 3.4% ( n = 7 dolphins). This low rate contrasts sharply with the much higher average match rate of 76% observed between the CCSAs. These differences in match rates suggest that both a California coastal stock and coastal Northern Baja California stock may exist, with only a limited degree of mixing between them. [ABSTRACT FROM AUTHOR]

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 ( FST = 0.012 , P = 0.0045). No significant nuclear differences were 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 ( hPCFG = 0.945, hNorthern = 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. [ABSTRACT FROM AUTHOR]

Range and movement data from boat-based photo-identification surveys of Pacific coast common bottlenose dolphins (Tursiops truncatus), carried out over a 6-yr period from 1996 to 2001, were collated and analyzed. Primary data sources were from surveys carried out in four Southern California Bight study areas: Ensenada (12 surveys), San Diego (95 surveys), Santa Monica Bay (170 surveys) and Santa Barbara (61 surveys). Additional data from surveys in Monterey Bay between 1990 and 1993 (84 surveys) were also included in some analyses. Photographic matches between the San Diego, Santa Monica Bay and Santa Barbara study areas ranged from a low of 42%to a high of 67% and averaged 53%. In addition, 32 of the 58 individuals (55%) identified in Monterey Bay also occurred in one or more of the four Southern California Bight study areas. Back-and-forth inter-study area movements recorded between 1996 and 2001, were exhibited by 157 of the 246 (52%) individuals sighted in two or more study areas. Minimum travel distances ranged from 104 to 965 km, with one individual documented to have traveled from Ensenada to Monterey Bay. The most rapid travel speed was 94.5 km/day. These results reinforce earlier characterizations of coastal bottlenose dolphins being highly mobile and capable of rapid travel along the Baja California and the southern and central California Pacific coastline. It is hypothesized that these extensive movements are related to fluctuations in local, regional and perhaps Pacific-wide oceanic conditions that affect prey productivity and availability; combined with unique foraging strategies that have developed to meet these environmental fluctuations. [ABSTRACT FROM AUTHOR]

The article presents the results of a study which analyzed bite marks and scars on western gray whales (Eschrichtius robustus) by killer whales (Orcinus orca). Topics of discussion include photoidentification of gray whales off Sakhalin Island, Russia, in the North Pacific Ocean, new scars by non-calf whales, and sex ratio among gray whales.

The California coastal stock of bottlenose dolphins (Tursiops truncatus) expanded its range north from the Southern California Bight, its historical range, into Central California coincident with the 1982-1983 El Niño event. Since the late 1980s, bottlenose dolphin sightings north of Central California have been increasingly reported. To determine the present-day northern range limit for these dolphins, photo-identification efforts were carried out from 2007 to 2018 in San Francisco Bay and nearby coastal waters during which 84 individuals were identified. The results demonstrate a significant range expansion along the Northern California coast at least as far as Sonoma County (38.7° N). Comparisons with photo-identification catalogs compiled south of San Francisco from 1981 to 2015 revealed that 92% of the 84 dolphins were matched to Monterey Bay (n = 77), Santa Barbara (n = 27), Santa Monica Bay (n = 29), Orange County (n = 9), Corona Del Mar (n = 2), San Diego (n = 31), and Ensenada, Mexico (n = 1). Many of the 84 dolphins (54%) showed long-range movements across the stock's range between the Southern California Bight and the San Francisco Bay Area. The greatest movement distance recorded was by two individuals first observed in San Diego, California, in the 1980s and subsequently in Puget Sound, Washington (47° N), in 2017, setting a coastal bottlenose dolphin long-distance movement record of at least 2,500 km. [ABSTRACT FROM AUTHOR]