Thomas R. Loughlin

HEALTH STATUS OF YOUNG ALASKA STELLER SEA LION PUPS (EUMETOPIAS JUBATUS) AS INDICATED BY BLOOD CHEMISTRY AND HEMATOLOGY

Blood chemistry and hematology were examined in 238 Steller sea lion pups (Eumetopias jubatus) to assess the health status of pups <1 month of age. Failure of juvenile recruitment (possibly due to nutritionally or physiologically compromised pups) into breeding populations has been proposed as a cause of recent declines of this endangered species in Alaska. To identify potential correlations with areas of high population decline, blood chemistry data were considered for three areas: eastern Aleutian Islands (low rates of population decline to stable populations), Gulf of Alaska (high rates of decline), and Southeast Alaska (stable to increasing population). Southeast Alaska pups showed elevated ketone body concentrations (beta-hydroxybutyrate,(beta-HBA)) and depressed glucose levels than pups in the Gulf of Alaska. Over 40% of the pups from Southeast Alaska had elevated beta-HBA concentrations suggesting they underwent longer periods of fasting than seen in pups from other areas. Hematocrit (Hct), hemoglobin concentration (Hb) and water content of the blood exhibited typical mammalian relationships. In summary, blood chemistry and hematology data showed no indication that Steller sea lion pups <1 month old from areas of population decline were nutritionally compromised.

Persistent organochlorines in Steller sea lion (Eumetopias jubatus) from the bulk of Alaska and the Bering Sea, 1976-1981

Abstract Organochlorine pesticides and polychlorinated biphenyls (PCBs) were determined in the blubber and liver of Steller sea lion collected from the bulk of Alaska and the Russian Bering Sea. PCBs were the predominant organochlorines in the blubber, ranging in concentration from 5.7 to 41 μg g−1 (lipid weight) in males and from 0.57 to 16 μg g−1 in females. Concentrations of DDTs (DDT and its metabolites) in the blubber ranged from 2.8 to 17 μg g−1 in males and from 0.19 to 6.5 μg g−1 in females. The levels of chlordane compounds (CHLs) and hexachlorocyclohexanes (HCHs) were one to three orders of magnitude lower than those of PCBs and DDTs. The residue levels of PCBs, DDTs and CHLs in males increased with age, whereas in females they decreased sharply after maturity, suggesting the transfer of organochlorines in large quantities during lactation. Transfer rate of organochlorines through lactation was estimated to be 80% for PCBs and 79% for DDTs of the total body of adult female. Concentrations of organochlorines in the liver of the Steller sea lion from Alaska, on a lipid weight basis, were similar to those in the blubber. In addition, liver showed age-dependent accumulation of PCBs, DDTs and CHLs, similar to that in the blubber. The concentrations of all the organochlorines detected in the liver were clearly correlated with those in the blubber, indicating the lipophilic nature of organochlorines in accumulation and movement in the animal body. Residue levels of PCBs and DDTs in the liver of male Steller sea lions from the Bering Sea were significantly lower than those from Alaska, suggesting that Bering Sea animals have different foraging areas from the animals of the bulk of Alaska.

Northern sea lion distribution and abundance: 1956-80

The present distribution and abundance of the northern sea lion (Eumetopias jubatus) was determined from surveys made between 1975 and 1980 and compared to estimates made approximately 20 years earlier. The previous population estimate of 240,000-300,000 is similar to our estimate of 245,000290,000. Declines appear to have occurred in the eastern Aleutian Islands, Pribilof Islands, and near Kodiak Island in the Gulf of Alaska. Increases may have occurred principally in the western and central Aleutians and west of Kodiak Island. Seasonal movements and indirect and direct effects by humans are considered the likely causes for regional changes in distribution and abundance. J. WILDL. MANAGE. 48(3):729-740 The breeding range of the northern sea lion, the most abundant sea lion in the northern hemisphere, extends around the North Pacific Ocean rim from the Kuril Islands and Okhotsk Sea, through the Aleutian Islands and southern Bering Sea, along Alaskas southern coast, and south to California (Scheffer 1958, Rice 1977). Northern sea lions are gregarious, polygynous, and utilize traditional rookeries and haul-out sites, usually located on remote and exposed islands. Extensive surveys were carried out between 1956 and 1958 along the Alaskan coast in the Gulf of Alaska (Mathisen and Lopp 1963) and in the 1960s in the Bering Sea and Aleutian Islands (Kenyon 1960, 1962c, Kenyon and Rice 1961). Kenyon and Rice (1961) summarized the available data and estimated that the entire northern sea lion population numbered between 240,000 and 300,000 in the late 1950s and early 1960s. Interest in the present status of northern sea lions has been stimulated by concern over the potential interactions between marine mammals, commercial fisheries, and oil and gas exploration in the Gulf of Alaska and Bering Sea and a marked decline in sea lion numbers in the Aleutian Islands (Braham et al. 1980). A coincidence of several recent land-based, boat, and aerial surveys to determine regional distribution and abundance of sea lions resulted in an unusually thorough coverage of sea lion distribution between 1975 and 1980. The objectives of this study are to describe the present world distribution of northern sea lions, to report our estimate of the relative population size, and to compare our estimate to that reported 20 years earlier by Kenyon and Rice (1961). We wish to acknowledge the cooperation of G. A. Antonelis, B. Bartels, M. L. Bonnell, D. G. Calkins, R. L. DeLong, T. J. Early, F. H. Fay, J. M. Francis, M. D. Griswold, C. A. Hansen, M. Hunt, B. W. Johnson, P. A. Johnson, P. Kozloff, J. L. Martin, M. K. Nerini, and A. B. Taber who allowed us to use their unpublished counts of sea lions. A. M. Johnson allowed us to use field records of 1959-60 and 1962-65 Aleutian Island surveys. K. W. Kenyon assisted us in reviewing his data from previous surveys in the Aleutian Islands. Graphics were made by R. P. Radek of the Northwest and Alaska Fish. Cent. Secretarial support was supplied by L. K. Hietala, M. A. Wood, and J. L. Waychoff of the Natl. Mar. Mammal Lab. (NMML). G. A. Antonelis, H. W. Braham, R. L. DeLong, R. L. Gentry, A. M. Johnson, D. W. Rice, D. E. Withrow, J. W. Brooks, and especially D. G. Calkins J. Wildl. Manage. 48(3):1984 729 This content downloaded from 157.55.39.177 on Tue, 15 Nov 2016 04:02:17 UTC All use subject to http://about.jstor.org/terms 730 SEA LION DISTRIBUTION * Loughlin et al. reviewed the manuscript and provided many helpful comments.

VARIATION OF MITOCHONDRIAL CONTROL REGION SEQUENCES OF STELLER SEA LIONS: THE THREE-STOCK HYPOTHESIS

Abstract Sequence variation in the mitochondrial DNA (mtDNA) control region was analyzed from 1,568 individuals representing nearly every rookery (n = 50) at which Steller sea lions (Eumetopias jubatus) are known to breed in significant numbers. Rookeries were grouped into regions and regions into stocks to examine structure at different spatial scales. Haplotype diversity (H = 0.9164 ± 0.0035) was high and nucleotide diversity (π = 0.00967 ± 0.00586) was moderate. No evidence was observed for significant genetic bottleneck effects. Previous studies of mtDNA recognized 2 stocks (eastern and western) and suggested the presence of 2 groups within the western stock. In this study, significant (P < 0.05) divergence of eastern stock (southeastern Alaska to California) animals from western stock animals was supported in analyses at all spatial scales. Likewise, rookeries and regions from Asia were found to be significantly different from all other western stock rookeries. This was most clearly demonstrated in regional comparisons. The Commander Islands rookery clearly associates with Alaskan western stock rookeries, not with the Asian rookeries. Within each of the 3 stocks there is significant isolation by distance among rookeries. This relationship does not hold for interstock comparisons, indicating that there are important barriers to gene flow among stocks. We recommend that the western stock be partitioned west of the Commander Islands, yielding a western stock that ranges from Prince William Sound west to the Commander Islands, and an Asian stock including rookeries from the Kamchatka Peninsula, Kuril Islands, and Sea of Okhotsk. The eastern stock remains unchanged and includes rookeries from southeastern Alaska through California.

Genetic Variability and Population Decline in Steller Sea Lions from the Gulf of Alaska

The western stock of the Steller sea lion (Eumetopias jubatus) was listed as endangered in 1997 due to its decline in numbers since the 1960s. We examined haplotypic diversity using nucleotide-sequence analysis of the control region of the mitochondrial DNA (mtDNA) from animals collected in 1976-1978 from the western and central Gulf of Alaska and compared results to previously published data from animals collected in the 1990s from the same geographic areas. No significant differences were found in frequencies of haplotypes between the two time periods, and genotypic diversity was high for all populations and time periods studied. It is concluded that, despite reduction in numbers, populations in the Gulf of Alaska have not lost appreciable genetic diversity, and if populations are allowed to recover, no long-term change in fitness is expected.

Accumulation of silver in the liver of three species of pinnipeds.

Silver in the three species of pinnipeds [northern fur seal (Callorhinus ursinus), Steller sea lion (Eumetopias jubatus), and harbor seal (Phoca vitulina)] caught in the North Pacific Ocean were analyzed using inductively coupled plasma-mass spectrometry, in order to understand accumulation and distribution of silver in pinnipeds. In northern fur seals, relatively high concentrations of silver were observed in the liver and body hair. Some 70% of the silver burden was concentrated in the liver. Hepatic silver concentrations were significantly correlated to age in northern fur seals (r = 0.766, P < 0.001, n = 49) and Steller sea lions (r = 0.496, P < 0.01, n = 28). Levels of silver concentrations per wet weight (microgram g-1) in the three pinnipeds ranged from 0.04 to 0.55 for northern fur seals, from 0.1 to 1.04 for Steller sea lions and from 0.03 to 0.83 for harbor seals. Silver concentrations in liver for all pinnipeds were significantly correlated with mercury, and selenium (P < 0.001). Molar ratios between silver to selenium approximated 1:180 in northern fur seals, 1:120 in Steller sea lions, and 1:60 in harbor seals. The silver-mercury molar ratios were approximately 1:170 in northern fur seals, and 1:80 both in the other species. Increase in silver accumulation in the liver was caused by the retention in nuclei and mitochondria fraction together with mercury and selenium in the cells of northern fur seals.

VARIATION IN MICROSATELLITES AND mtDNA ACROSS THE RANGE OF THE STELLER SEA LION, EUMETOPIAS JUBATUS

Abstract Genetic variation at 6 nuclear microsatellite loci with biparental inheritance and the maternally inherited mitochondrial DNA (mtDNA) was studied at 3 geographic scales (rookeries, regions, and stocks) in Steller sea lions (Eumetopias jubatus). Genetic variation was high in both nuclear and mtDNA markers as revealed by a near range-wide survey of 21 rookeries. However, population structure was not well defined, and there was no obvious phylogeographic pattern to the distribution of microsatellite alleles. This contrasts with a clear phylogeographic pattern revealed by control-region sequences of mtDNA in which 2 well-differentiated stocks, eastern and western, are defined as well as 2 distinct groups, Asian and central, in the western stock. Effective migration estimates are consistently higher for the nuclear loci than for mtDNA. The difference in patterns between the biparentally and maternally inherited genetic markers can be explained by relatively high male dispersal rates and female philopatry, or else there has been insufficient time since populations have been isolated for the nuclear loci to have diverged. It is recommended that the presently accepted stock structure be retained for management purposes and that further studies be carried out to test the male dispersal hypothesis.

Distribution of heavy metals in muscle, liver and kidney of northern fur seal (Callorhinus ursinus) caught off Sanriku, Japan and from the Pribilof Islands, Alaska

The concentrations of iron, manganese, zinc, copper, cadmium, and mercury were determined in muscle, liver and kidney of 67 northern fur seals (Callorhinus ursinus) collected off Sanriku, Japan, and from the Pribilof Islands, Alaska. Almost all the elements except cadmium were highest in liver. Cadmium levels in kidney were higher than those in liver and muscle for all animals analyzed. Concentrations of mercury increased significantly with age in muscle, liver and kidney, as did iron levels in muscle and liver and cadmium levels in muscle, while manganese concentrations decreased with age in muscle and kidney. The kidney also showed decreased copper concentration with age. Cadmium concentrations of the northern fur seals in this study were higher than the other otariids, reflecting a predominantly squid diet. Concentrations of manganese and mercury were found to be higher in the fur seals caught off Sanriku than in animals from the Pribilof Islands, while those of zinc and cadmium were found to be lower. Variable concentrations of cadmium might have been attributed to those in seawaters. Discriminant analysis of heavy metal concentrations was used to identify habitat. Sixty-three of 67 animals (94%) were correctly classified using this technique. Heavy-metal concentrations in tissues may provide a useful method to elucidate the primary feeding grounds of fur seals.

Bacular size, growth, and allometry in the largest extant otariid, the Steller sea lion (Eumetopias jubatus)

Abstract Bacula are relatively small in terrestrially mating species of pinnipeds (otariids and elephant seals, Mirounga), perhaps reflecting adaptive size reduction to minimize bacular fracture. Fur seals and sea lions (Otariidae) are a good group with which to investigate this question, because most species copulate solely on land and body size varies interspecifically. We studied bacular size and relative growth in the largest extant otariid, the Steller sea lion (Eumetopias jubatus). Bacula roughly tripled in length and increased 30-fold in mass between 1 and 8 years of age. Allometric relationships changed over development; bacular length and mass changed from being initially positively allometric to body length to negatively allometric and isometric, respectively; bacular mass and thickness were positively allometric to body length throughout life, and apical growth was isometric then was positively allometric to bacular length. In adults (>7 years of age), bacula averaged 18.1 cm length (6.2% of body length), 36.7 g mass, and 2.02 g/cm density (mass : length). The baculum of Eumetopias is about the same length relative to body length as in other adult male otariids but is about twice the density, presumably to increase strength. Information on small or aquatically mating species of otariid are needed to extend our findings and interpretations.

Regional differences in the spatial and temporal heterogeneity of oceanographic habitat used by Steller sea lions.

Over the past three decades, the decline and altered spatial distribution of the western stock of Steller sea lions (Eumetopias jubatus) in Alaska have been attributed to changes in the distribution or abundance of their prey due to the cumulative effects of fisheries and environmental perturbations. During this period, dietary prey occurrence and diet diversity were related to population decline within metapopulation regions of the western stock of Steller sea lions, suggesting that environmental conditions may be variable among regions. The objective of this study, therefore, was to examine regional differences in the spatial and temporal heterogeneity of oceanographic habitat used by Steller sea lions within the context of recent measures of diet diversity and population trajectories. Habitat use was assessed by deploying satellite-depth recorders and satellite relay data loggers on juvenile Steller sea lions (n = 45) over a five-year period (2000-2004) within four regions of the western stock, including the western, central, and eastern Aleutian Islands, and central Gulf of Alaska. Areas used by sea lions during summer months (June, July, and August) were demarcated using satellite telemetry data and characterized by environmental variables (sea surface temperature [SST] and chlorophyll a [chl a]), which possibly serve as proxies for environmental processes or prey. Spatial patterns of SST diversity and Steller sea lion population trends among regions were fairly consistent with trends reported for diet studies, possibly indicating a link between environmental diversity, prey diversity, and distribution or abundance of Steller sea lions. Overall, maximum spatial heterogeneity coupled with minimal temporal variability of SST appeared to be beneficial for Steller sea lions. In contrast, these patterns were not consistent for chl a, and there appeared to be an ecological threshold. Understanding how Steller sea lions respond to measures of environmental heterogeneity will ultimately be useful for implementing ecosystem management approaches and developing additional conservation strategies.