Kathryn J. Frost

Phylogeography, population structure and dispersal patterns of the beluga whale Delphinapterus leucas in the western Nearctic revealed by mitochondrial DNA

The recent evolutionary history, population structure and movement patterns of beluga whales in the western Nearctic were inferred from an analysis of mitochondrial DNA control region sequence variation of 324 whales from 32 locations representing five summer concentration areas in Alaska and north‐west Canada. Phylogenetic relationships among haplotypes were inferred from parsimonious networks, and genetic subdivision was examined using haplotypic frequency‐based indices and an analysis of variance method modified for use with interhaplotypic distance data. MtDNA relationships were characterized by a series of star‐like phylogenies which, when viewed in conjunction with information on haplotype frequency and distribution, suggested a rapid radiation of beluga whales into the western Nearctic following the Pleistocene, and an early divergence of the Beaufort Sea from the Chukchi and Bering Seas subpopulations. Overall nucleotide diversity was low (0.51%) yet all major summering concentrations were significantly differentiated (ΦST= 0.33) from one another. Stratification of samples by gender and age from the three northernmost subpopulations suggested that female cohorts from neighbouring subpopulations were more differentiated than males. Further stratification of adult animals by age revealed that older adults were substantially less subdivided among locations than younger adults, particularly for males, suggesting that dispersal, although limited, is biased toward older adult males. Overall, the patterns of mtDNA variation in beluga whales indicated that the summering concentrations are demographically, if not phyletically distinct. Population structure appears to be maintained primarily by natal homing behaviour, while asymmetries in dispersal may be associated with the type of mating system.

A Bayesian hierarchical model for monitoring harbor seal changes in Prince William Sound, Alaska

Bayesian hierarchical models were used to assess trends of harbor seals, Phoca vitulina richardsi, in Prince William Sound, Alaska, following the 1989 Exxon Valdez oil spill. Data consisted of 4–10 replicate observations per year at 25 sites over 10 years. We had multiple objectives, including estimating the effects of covariates on seal counts, and estimating trend and abundance, both per site and overall. We considered a Bayesian hierarchical model to meet our objectives. The model consists of a Poisson regression model for each site. For each observation the logarithm of the mean of the Poisson distribution was a linear model with the following factors: (1) intercept for each site and year, (2) time of year, (3) time of day, (4) time relative to low tide, and (5) tide height. The intercept for each site was then given a linear trend model for year. As part of the hierarchical model, parameters for each site were given a prior distribution to summarize overall effects. Results showed that at most sites, (1) trend is down; counts decreased yearly, (2) counts decrease throughout August, (3) counts decrease throughout the day, (4) counts are at a maximum very near to low tide, and (5) counts decrease as the height of the low tide increases; however, there was considerable variation among sites. To get overall trend we used a weighted average of the trend at each site, where the weights depended on the overall abundance of a site. Results indicate a 3.3% decrease per year over the time period.

Movements and Behavior of Satellite- tagged Spotted Seals (Phoca largha) in the Bering and Chukchi Seas

Abstract Satellite-linked tags were attached to 12 spotted seals (Phoca largha) captured at a coastal lagoon in the eastern Chukchi Sea during August 1991–1993. Movements of seals were tracked for 32–298 days using the Argos system. Of 9,651 total location records obtained, 7,268 were usable. Individual seals were located on 41–96% of the days that tags were operational. During August–November, tagged seals alternated haul-outs at coastal sites lasting 1–304 h with trips to sea of 14–901 h. Coastal haul-outs occurred at 14 sites in western Alaska and eastern Russia. On several trips to sea, seals covered distances of more than 1,000 km. Movement southward from the Chukchi Sea generally began in October, with most of the seals passing through the Bering Strait during November. Seals first hauled out on sea ice in October (Chukchi Sea) or November (Bering Sea), and generally moved southward during October–December as sea-ice coverage increased. Seven seals, whose transmitters were still operating, spent December to June in the Bering Sea region between Kuskokwim Bay and Anadyr Gulf, which corresponded to the location of the ice front. The seals made active east-west movements within the ice front. Spotted seals are unlike other ice-breeding seals in that they regularly use coastal haul-outs during summer and autumn. Compared to the closely related Pacific harbor seal (Phoca vitulina richardsi), spotted seals make much longer trips to sea and spend longer continuous periods at their haul-outs during summer and autumn.

Diet of beluga whales, Delphinapterus leucas, in Alaska from stomach contents, March-November

At least fi ve stocks of beluga whales, Delphinapterus leucas, are found in Alaska waters: Beaufort Sea, eastern Chukchi Sea, eastern Bering Sea, Bristol Bay, and Cook Inlet. The two northernmost stocks (Beaufort Sea and eastern Chukchi Sea) are highly migratory; the two southernmost stocks (Bristol Bay and Cook Inlet) are nonmigratory. Little is known about the seasonal movements and distribution of the eastern Bering Sea stock. Beluga populations in Alaska are thought to be stable or increasing, except for the Cook Inlet stock which is listed as endangered under the Endangered Species Act. We analyzed stomach contents from beluga whales collected between the months of March and November taken in subsistence harvests, from belugas found dead, and from belugas collected for research. We describe prey species and their percent frequency of occurrence (% FO) as well as potential biases from the seasonality of prey relative to the timing of sampling, and differential feeding and digestion. Diet was highly variable among stocks. The predominant fi sh species of the Beaufort Sea stock was Arctic cod, Boreogadus saida (21% FO), although shrimp (60% FO) and smoothskin octopus, Benthoctopus leioderma (42% FO) were found more frequently. Although the eastern Chukchi Sea stock ate more saffron cod, Eleginus gracilis (7% FO) than Arctic cod (3% FO), shrimp (73% FO) and echiurids (27% FO) were more prevalent than fi sh. The eastern Bering Sea stock had the most diverse diet, and dominant fi sh species included saffron cod (95% FO), rainbow smelt, Osmerus mordax (62% FO), several species of sculpin (Family Cottidae) and fl atfi sh (Family Pleuronectidae), both at 48% FO, and Arctic cod at 43%. Dominant invertebrates included shrimp (86% FO), with polychaetes, isopods, bivalves, amphipods, and echiurids ranging from 29 to 38% FO. Pacifi c salmon, Onchorhyncus spp., predominated over cod in Bristol Bay (81% FO) and Cook Inlet (67% FO) beluga stocks, and invertebrates appeared to be less prevalent prey. In Bristol Bay, smelt were also eaten more often (43% FO) than cod (3% FO), while in Cook Inlet cod were eaten more often (39% FO) than smelt (11% FO). Invertebrates were common in the diet of all Alaska beluga stocks and shrimp (mostly from the family Crangonidae) were the most prevalent. Introduction At least fi ve stocks of beluga whales, Delphinapterus leucas, occur in the waters of Alaska (Fig. 1). These stocks were tentatively identifi ed by their summer distributions (Frost and Lowry, 1990; Richard et al., 2001), and were later confi rmed genetically (O’Corry-Crowe et al., 1997, 2002, 2010). The distribution of beluga whales in Alaska is discontinuous from Yakutat Bay1, 2 to Cook Inlet to Bristol Bay. The entire area from Bristol Bay northward and eastward to Canada is used by belugas; the Bering and Chukchi seas are used year-round and the Beaufort Sea is used in summer (Frost and Lowry, 1990). 1There is a small group of <20 belugas that appear to be resident in Yakutat Bay, a deepwater fi ord (Laidre et al., 2000; Allen and Angliss, 2011) 2O’Corry-Crowe, G., W. Lucey, C. Bonin, E. Henniger, and R. Hobbs. 2006. The ecology, status and stock identify of beluga whales, Delphinapterus leucas, in Yakutat Bay, Alaska. Rep. to U.S. Mar. Mamm. Comm., NMFS-YSB-YTT, 22 p. Beluga whales in Alaska appear to follow one of two life history strategies: migratory and nonmigratory. Migratory stocks use shallow nearshore and deepwater offshore habitats (Hazard, 1988; Frost and Lowry, 1990), and include the eastern Chukchi Sea stock (population size ~4,000 (Allen and Angliss, 2011)) and the Beaufort Sea or Mackenzie stock (population size ~39,000 (Harwood et al., 1996; Allen and Angliss, 2011)). Nonmigratory stocks use shallow, estuarine habitats year-round and include the Bristol Bay and Cook Inlet stocks. The Bristol Bay population is increasing (Lowry et al., 2008) and is estimated to be ~3,000 (Allen and Angliss, 2011). Local sightings and satellite telemetry confi rm that belugas occur in Bristol Bay in all months of the year (Harrison and Hall, 1978; Frost and Lowry, 1990; Lensink3; Quakenbush and Citta4; Quaken bush5). The population in Cook Inlet is estimated to be 312 whales and appears to be decreasing at 1.6% per year (Hobbs et al., 2015). The population declined dramatically between 1994 and 1998 (Hobbs et al., 2000) and the stock was determined to be depleted under the Marine Mammal Protection Act in 2000 (NOAA, 2000); the original cause of the decline is believed to be overharvest. Between 1999 and 2006 the harvest was restricted to fi ve 3Lensink, C. J. 1961. Status report: beluga studies. Alaska Dep. Fish Game, Juneau. Unpubl. rep., 38 p. 4Quakenbush, L., and J. Citta. 2006. Fall movements of beluga whales captured in the Nushagak River in September 2006. Unpubl. rep. to Alaska Beluga Whale Committee, P.O. Box 69, Barrow Alaska 99723, 9 p. 5Quakenbush, L., Alaska Dep. Fish Game, 1300 College Road, Fairbanks. Unpubl. data.

SEROLOGIC SURVEY FOR BRUCELLA SPP., PHOCID HERPESVIRUS-1, PHOCID HERPESVIRUS-2, AND PHOCINE DISTEMPER VIRUS IN HARBOR SEALS FROM ALASKA, 1976–1999

Harbor seals (Phoca vitulina richardsi) were captured in the coastal regions of Southeast Alaska, Gulf of Alaska, Prince William Sound (PWS), and Kodiak Island during 1976–1999. Blood was collected from 286 seals. Sera were tested for evidence of exposure to Brucella spp., phocid herpesvirus-1 (PhoHV-1), phocid herpesvirus-2 (PhHV-2), and phocine distemper virus (PDV). Antibody prevalence rates were 46% (46/100) for Brucella spp., 93% (225/243) for PhoHV-1, 0% (0/286) for PhHV-2, and 1% (2/160) for PDV. Antibody prevalence for Brucella spp. was directly related to host age. Antibody prevalence for PhoHV-1 was higher in PWS as compared to the other three regions. No evidence of mortality attributable to these four agents was observed during the course of this study. Based on the results of this survey, none of these agents is considered a significant mortality factor in harbor seals from the four regions of coastal Alaska included in the study.

Habitat selection and seasonal movements of young bearded seals (Erignathus barbatus) in the Bering Sea.

The first year of life is typically the most critical to a pinniped’s survival, especially for Arctic phocids which are weaned at only a few weeks of age and left to locate and capture prey on their own. Their seasonal movements and habitat selection are therefore important factors in their survival. During a cooperative effort between scientists and subsistence hunters in October 2004, 2005, and 2006, 13 female and 13 male young (i.e., age <2) bearded seals (Erignathus barbatus) were tagged with satellite-linked dive recorders (SDRs) in Kotzebue Sound, Alaska. Shortly after being released, most seals moved south with the advancing sea-ice through the Bering Strait and into the Bering Sea where they spent the winter and early spring. The SDRs of 17 (8 female and 9 male) seals provided frequent high-quality positions in the Bering Sea; their data were used in our analysis. To investigate habitat selection, we simulated 20 tracks per seal by randomly selecting from the pooled distributions of the absolute bearings and swim speeds of the tagged seals. For each point in the observed and simulated tracks, we obtained the depth, sea-ice concentration, and the distances to sea-ice, open water, the shelf break and coastline. Using logistic regression with a stepwise model selection procedure, we compared the simulated tracks to those of the tagged seals and obtained a model for describing habitat selection. The regression coefficients indicated that the bearded seals in our study selected locations near the ice edge. In contrast, aerial surveys of the bearded seal population, predominantly composed of adults, indicated higher abundances in areas farther north and in heavier pack ice. We hypothesize that this discrepancy is the result of behavioral differences related to age. Ice concentration was also shown to be a statistically significant variable in our model. All else being equal, areas of higher ice concentration are selected for up to about 80%. The effects of sex and bathymetry were not statistically significant. The close association of young bearded seals to the ice edge in the Bering Sea is important given the likely effects of climate warming on the extent of sea-ice and subsequent changes in ice edge habitat.

Spotted Seal: Phoca largha

Summary Spotted seals (Phoca largha) occur primarily in seasonally ice-covered seas of the North Pacific Ocean. Breeding populations occur in the Bering Sea, Sea of Okhotsk, Yellow Sea, and Sea of Japan. This species is closely related to the harbor seal (Phoca vitulina). However, these sibling species have adapted very differently to their environments; spotted seals primarily breed and molt on sea ice and harbor seals on land.