Abstract Pacific harbor seals ( Phoca vitulina richardii ) were surveyed throughout their range along Alaska coasts over a 28-year period. Twelve management stocks, delineated on the basis of evidence for demographic independence, were monitored for abundance and trends. We employed a two-stage Bayesian hierarchical analysis that integrated aerial survey counts with satellite-linked bio-logger haul-out timelines to account for the proportion of seals in the water and not visible to survey observers and cameras. Overall, harbor seals were abundant (201,122 seals in 2023) but, during the span of our study the population (stock) trends varied. The first half of our study was characterised primarily by growth, with a peak abundance of approximately 225,000 seals in 2015. Since then trends have been variable, with some stocks (e.g., Bristol Bay) showing continued growth while others (e.g. Prince William Sound, South Kodiak) declined. The recent regional declines coincided with observed climate anomalies (e.g., marine heatwaves) and the rapid retreat of tidewater glaciers. Our results provide a basis for managing this species in Alaska, which is protected under the Marine Mammal Protection Act; a vital nutritional and cultural resource for Alaska Native communities; and an important sentinel of change in the Northeast Pacific marine ecosystem.

Freshwater populations of typically marine species present unique opportunities to investigate biodiversity, evolutionary divergence, and the adaptive potential and niche width of species. A few pinniped species have populations that reside solely in freshwater. The harbour seals inhabiting Iliamna Lake, Alaska constitute one such population. Their remoteness, however, has long hindered scientific inquiry. We used DNA from seal scat and tissue samples provided by Indigenous hunters to screen for mitochondrial DNA and microsatellite variation within Iliamna Lake and eight regions across the Pacific Ocean. The Iliamna seals (i) were substantially and significantly discrete from all other populations ( [Formula: see text]F st-mtDNA = 0.544, [Formula: see text]Φ st - mtDNA = 0.541, [Formula: see text]F st-microsatellites = 0.308), (ii) formed a discrete genetic cluster separate from all marine populations (modal ∆k = 2, PC1 = 14.8%), had (iii) less genetic diversity (Hd, π, H exp), and (iv) higher inbreeding (F) than marine populations. These findings are both striking and unexpected revealing that Iliamna seals have likely been on a separate evolutionary trajectory for some time and may represent a unique evolutionary legacy for the species. Attention must now be given to the selective processes driving evolutionary divergence from harbour seals in marine habitats and to ensuring the future of the Iliamna seal.

Harbor seals in Iliamna Lake, Alaska, are a small, isolated population, and one of only two freshwater populations of harbor seals in the world, yet little is known about their abundance or risk for extinction. Bayesian hierarchical models were used to estimate abundance and trend of this population. Observational models were developed from aerial survey and harvest data, and they included effects for time of year and time of day on survey counts. Underlying models of abundance and trend were based on a Leslie matrix model that used prior information on vital rates from the literature. We developed three scenarios for variability in the priors and used them as part of a sensitivity analysis. The models were fitted using Markov chain Monte Carlo methods. The population production rate implied by the vital rate estimates was about 5% per year, very similar to the average annual harvest rate. After a period of growth in the 1980s, the population appears to be relatively stable at around 400 individuals. A population viability analysis assessing the risk of quasi-extinction, defined as any reduction to 50 animals or below in the next 100 years, ranged from 1% to 3%, depending on the prior scenario. Although this is moderately low risk, it does not include genetic or catastrophic environmental events, which may have occurred to the population in the past, so our results should be applied cautiously.

Populations of Steller sea lions, northern fur seals, and northern sea otters declined substantially during recent decades in the Bering Sea and Aleutian Islands region, yet the population status of harbor seals has not been assessed adequately. We determined that counts obtained during skiff-based surveys conducted in 1977–1982 represent the earliest estimate of harbor seal abundance throughout the Aleutian Islands. By comparing counts from 106 islands surveyed in 1977–1982 (8,601 seals) with counts from the same islands during a 1999 aerial survey (2,859 seals), we observed a 67% decline over the ∼20-yr period. Regionally, the largest decline of 86% was in the western Aleutians (n = 7 islands), followed by 66% in the central Aleutians (n = 64 islands), and 45% in the eastern Aleutians (n = 35 islands). Harbor seal counts decreased at the majority of islands in each region, the number of islands with >100 seals decreased ∼70%, and the number of islands with no seals counted increased ∼80%, indicating that harbor seal abundance throughout the Aleutian Islands was substantially lower in the late 1990s than in the 1970s and 1980s.

AbstractWe monitored the haul‐out behavior of 68 radio‐tagged harbor seals (Phoca vitulina) during the molt season at two Alaskan haul‐out sites (Grand Island, August‐September 1994; Nanvak Bay, August‐September 2000). For each site, we created a statistical model of the proportion of seals hauled out as a function of date, time of day, tide, and weather covariates. Using these models, we identified the conditions that would result in the greatest proportion of seals hauled out. Although those “ideal conditions” differed between sites, the proportion of seals predicted to be hauled out under those conditions was very similar (81.3% for Grand Island and 85.7% for Nanvak Bay). The similar estimates for both sites suggest that haul‐out proportions under locally ideal conditions may be constant between years and geographic regions, at least during the molt season.

A bstract The abundance of harbor seals ( Phoca vitulina richardii ) has declined in recent decades at several Alaska locations. The causes of these declines are unknown, but there is concern about the status of the populations, especially in the Gulf of Alaska. To assess the status of harbor seals in the Gulf of Alaska, we conducted aerial surveys of seals on their haul‐out sites in August‐September 1996. Many factors influence the propensity of seals to haul out, including tides, weather, time of day, and time of year. Because these “covariates” cannot simultaneously be controlled through survey design, we used a regression model to adjust the counts to an estimate of the number of seals that would have been ashore during a hypothetical survey conducted under ideal conditions for hauling out. The regression, a generalized additive model, not only provided an adjustment for the covariates, but also confirmed the nature and shape of the covariate effects on haul‐out behavior. The number of seals hauled out was greatest at the beginning of the surveys (mid‐August). There was a broad daily peak from about 1100–1400 local solar time. The greatest numbers were hauled out at low tide on terrestrial sites. Tidal state made little difference in the numbers hauled out on glacial ice, where the area available to seals did not fluctuate with the tide. Adjusting the survey counts to the ideal state for each covariate produced an estimate of 30,035 seals, about 1.8 times the total of the unadjusted counts (16,355 seals). To the adjusted count, we applied a correction factor of 1.198 from a separate study of two haul‐out sites elsewhere in Alaska, to produce a total abundance estimate of 35,981 (SE 1,833). This estimate accounts both for the effect of covariates on survey counts and for the proportion of seals that remained in the water even under ideal conditions for hauling out.

The worldwide literature on management of spotted seals, Phoca largha, was reviewed and updated, and aerial surveys weref lown in 1992 and 1993 to determine the species' distribution and abundance in U.S. waters. In April, spotted seals were found only in the Bering Sea ice front. In June, they were seen along deteriorating ice floes and fast ice in Norton Sound. Surveys along most of Alaska's western coast in August and September found over 2,500 spotted seals in Kuskokwim Bay and concentrations of 100-400 seals around Nunivak Island, Scammon Bay, Golovnin Bay/Norton Sound, Cape Espenberg/Kotzebue Sound, and Kasegaluk Lagoon. All of these sites have been used by spotted seals in the past. The sum of the highest counts, irrespective of year, was 3,570 seals (CV =0.06). This is not an abundance estimate for all spotted seals in the Bering Sea, because it does not account for animals in the water, and we did not survey the Asian coast and some islands. Also, spotted seals and harbor seals, Phoca vitulina, are too similar in appearance to be identified accurately from the air, so our results probably include a mix of these species where their ranges overlap.

Marine Mammal ScienceVolume 11, Issue 2 p. 231-240 OBSERVATIONS OF RISSO DOLPHINS, GRAMPUS GRISEUS WITH GRAY WHALES, ESCHRICHTIUS ROBUSTUS Kim E. W. Shelden, Kim E. W. Shelden National Marine Mammal Laboratory, NMFS, NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, BIN C15700, Seattle, Washington 98115-0070, U.S.A.; Hopkins Marine Station, Stanford University, Department of Biological Sciences, Pacific Grove, California 93950, U.S.A.; National Marine Mammal Laboratory, NMFS, NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, BIN C15700, Seattle, Washington 98115-0070, U.S.A.Search for more papers by this authorAlan Baldridge, Alan Baldridge National Marine Mammal Laboratory, NMFS, NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, BIN C15700, Seattle, Washington 98115-0070, U.S.A.; Hopkins Marine Station, Stanford University, Department of Biological Sciences, Pacific Grove, California 93950, U.S.A.; National Marine Mammal Laboratory, NMFS, NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, BIN C15700, Seattle, Washington 98115-0070, U.S.A.Search for more papers by this authorDavid E. Withrow, David E. Withrow National Marine Mammal Laboratory, NMFS, NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, BIN C15700, Seattle, Washington 98115-0070, U.S.A.; Hopkins Marine Station, Stanford University, Department of Biological Sciences, Pacific Grove, California 93950, U.S.A.; National Marine Mammal Laboratory, NMFS, NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, BIN C15700, Seattle, Washington 98115-0070, U.S.A.Search for more papers by this author Kim E. W. Shelden, Kim E. W. Shelden National Marine Mammal Laboratory, NMFS, NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, BIN C15700, Seattle, Washington 98115-0070, U.S.A.; Hopkins Marine Station, Stanford University, Department of Biological Sciences, Pacific Grove, California 93950, U.S.A.; National Marine Mammal Laboratory, NMFS, NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, BIN C15700, Seattle, Washington 98115-0070, U.S.A.Search for more papers by this authorAlan Baldridge, Alan Baldridge National Marine Mammal Laboratory, NMFS, NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, BIN C15700, Seattle, Washington 98115-0070, U.S.A.; Hopkins Marine Station, Stanford University, Department of Biological Sciences, Pacific Grove, California 93950, U.S.A.; National Marine Mammal Laboratory, NMFS, NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, BIN C15700, Seattle, Washington 98115-0070, U.S.A.Search for more papers by this authorDavid E. Withrow, David E. Withrow National Marine Mammal Laboratory, NMFS, NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, BIN C15700, Seattle, Washington 98115-0070, U.S.A.; Hopkins Marine Station, Stanford University, Department of Biological Sciences, Pacific Grove, California 93950, U.S.A.; National Marine Mammal Laboratory, NMFS, NOAA, Alaska Fisheries Science Center, 7600 Sand Point Way NE, BIN C15700, Seattle, Washington 98115-0070, U.S.A.Search for more papers by this author First published: April 1995 https://doi.org/10.1111/j.1748-7692.1995.tb00521.xCitations: 11AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Literature Cited Andrews, R. C. 1914. Monographs of the Pacific cetacea. I. The California gray whale (Rhachianectes glaucus Cope). Its history, habits, external anatomy, osteology and relationships. Memoirs of the American Museum of Natural History (New Series) 1: 227– 287. Baldridge, A. 1972. Killer whales attack and eat a gray whale. Journal of Mammalogy 53: 898– 900. Buckland, S. T., J. M. Breiwick, K. L. Cattanach and J. L. Laake 1993. Estimated population size of the California gray whale. Marine Mammal Science 9: 235– 249. Burrage, B. R. 1964. An observation regarding gray whales and killer whales. Transactions of the Kansas Academy of Science 67: 550– 551. Dohl, T. P., R. C. Guess, M. L. Duman and R. C. Helm 1983. Cetaceans of central and northern California, 1980–1983: Status, abundance, and distribution. Final report submitted to Pacific OCS Region, Minerals Management Service, U.S. Department of the Interior, Los Angeles , California . OCS Study MMS 84–0045. 284 pp. Fiscus, C. H., and K. Niggol 1965. Observations of cetaceans off California, Oregon, and Washington. U.S. Fish and Wildlife Service Special Scientific Report-Fisheries 498. 27 pp. Goley, P. D., and J. M. Straley 1994. Attack on gray whales (Eschrichtius robustus) in Monterey Bay, California, by killer whales (Orcinus orca) previously identified in Glacier Bay, Alaska. Canadian Journal of Zoology 72: 1528– 1530. Hubbs, C. L. 1960. The marine vertebrates of the outer coast. Pages 134– 147 in Symposium: The biogeography of Baja California and adjacent seas. Part II, Marine biotas. Systematic Zoology 9(3 & 4). Kellogg, R. 1940. Whales, giants of the sea. National Geographic 77(1): 35– 90. Kruse, S. L. 1989. Aspects of the biology, ecology and behavior of Risso's dolphin (Grampus griseus) of the California coast. Masters of Science. University of California Santa Cruz. 129 pp. Leatherwood, J. S. 1974. A note on gray whale behavioral interactions with other marine mammals. Marine Fisheries Review 36(4): 50– 51. Leatherwood, S., W. F. Perrin, V. L. Kirby, C. L. Hubbs and M. Dahlheim 1980. Distribution and movements of Risso's dolphin, Grampus griseus, in the eastern North Pacific. Fishery Bulletin, U.S. 77: 95l– 963. Leatherwood, S., R. R. Reeves, W. F. Perrin and W. E. Evans 1982. Whales, dolphins, and porpoises of the eastern North Pacific and adjacent Arctic waters: A guide to their identification. NOAA Technical Report NMFS Circular 444. 245 pp. Leatherwood, S., B. S. Stewart and P. A. Folkens 1987. Cetaceans of the Channel Islands National Marine Sanctuary. Report to NOAA, Channel Islands National Marine Sanctuary, NMFS. 66 pp. Ljungblad, D. K., and S. E. Moore 1983. Killer whales (Orcinus orca) chasing gray whales (Eschrichtius robustus) in the northern Bering Sea. Arctic 36: 361– 364. Morejohn, G. V. 1968. A killer whale-gray whale encounter. Journal of Mammalogy 49: 327– 328. Shane, S. H. 1994. Occurrence and habitat use of marine mammals at Santa Catalina Island, California from 1983–91. Bulletin of Southern California Academy Science 93(l): 13– 29. Tarpy, C. 1979. Killer whale attack. National Geographic 155(4): 542– 545. Ternullo, R. L., N. A. Black, A. Baldridge and D. L. Shearwater 1993. Occurrence, distribution, and predation behavior of killer whales (Orcinus orca) in Monterey Bay. Abstracts of the Tenth Biennial Conference on the Biology of Marine Mammals, November 11–15, Galveston , Texas . Tctomilin, A. G. 1957. Zveri SSSR i prilezhashchikh stran, Vol. IX Kitoobraznye [Mammals of the USSR and adjacent countries, Volume IX Cetacea. [In Russian) Izdatel Akademi Nauk SSSR, Moskva. (Translated by Israel Program for Scientific Translation, Jerusalem, 1967). 717 pp. Citing Literature Volume11, Issue2April 1995Pages 231-240 ReferencesRelatedInformation

Three bowhead whales were found with calves more than once in interyear comparisons of aerial photographs. These indicated calving intervals of 4, 4, and 7 years, the first such direct evidence.