An Accounting of the Sources of Steller Sea Lion, Eumetopias jubatus, Mortality

During 1991–2000, the west-are additional mortalities that fueled the ern stock of Steller sea lions, Eumetopias decline. We tabulated the levels of reported jubatus, declined at 5.03% (SE = 0.25%) anthropogenic sources of mortality (sub- per year, statistically significant rates (P < sistence, incidental take in fisheries, and 0.10) in all but the eastern Aleutian Islands research), estimated another (illegal shoot-region. The greatest rates of declines oc-ing), then approximated levels of predation curred in the eastern and central Gulf of Alas-(killer whales and sharks). We attempted to ka and the western Aleutian Islands (> 8.2% partition the various sources of “additional” per year). Using a published correction mortalities as anthropogenic and as addifactor, we estimated the total non-pup pop-tional mortality including some predation. ulation size in Alaska of the western stock We classified 436 anthropogenic mortalities of Steller sea lions to be about 33,000 ani-and 769 anthropogenic plus some predation mals. Based on a published life table and mortalities as “mortality above replace-the current rate of decline, we estimate that ment”; this accounted for 26% and 46% of the total number of mortalities of non-pup the estimated total level of “mortality above Steller sea lions during 1991–2000 was replacement”, respectively. The remaining about 6,383 animals; of those, 4,718 (74%) mortality (74% and 54%, respectively) was are mortalities that would have occurred if not attributed to a specific cause and may be the population were stable, and 1,666 (26%) the result of nutritional stress.

Distribution and biology of prowfish (Zaprora silenus) in the northeast Pacific

The prowfish (Zaprora silenus) is an infrequent component of bottom trawl catches collected on stock assessment surveys. Based on presence or absence in over 40,000 trawl catches taken throughout Alaskan waters southward to southern California, prowfish are most frequently encountered in the Gulf of Alaska and the Aleutian Islands at the edge of the continental shelf. Based on data from two trawl surveys, relative abundance indicated by catch per swept area reaches a maximum between 100 m and 200 m depth and is much higher in the Aleutian Islands than in the Gulf of Alaska. Females weigh 3.7% more than males of the same length. Weight-length functions are W (g) = 0.0164 L2.92 (males) and W = 0.0170 L2.92 (females). Length at age does not differ between sexes and is described by L = 89.3(1 – e–0.181(t+0.554)), where L is total length in cm and t is age in years. Females reached 50% maturity at a length of 57.0 cm and an age of 5.1 years. Prowfish diet is almost entirely composed of gelatinous zooplankton, primarily scyphozoa and salps.

Diving behavior of immature Steller sea lions (Eumetopias jubatus)

Understanding the ontogenetic relationship between juvenile Steller sea lions (Eumetopias jubatus) and their foraging habitat is key to understanding their relationship to available prey and ultimately their survival. We summarize dive and movement data from 13 young-of-the-year (YOY) and 12 yearling Steller sea lions equipped with satellite dive recorders in the Gulf of Alaska and Aleutian Islands (n=18), and Washington (n=7) from 1994 to 2000. A total of 1413 d of transmission (x =56.5 d, range: 14.5–104.1 d) were received. We recorded 222,073 dives, which had a mean depth of 18.4 m (range of means: 5.8−67.9 m; SD=16.4). Alaska YOY dived for shorter periods and at shallower depths (mean depth=7.7 m, mean duration=0.8 min, mean maximum depth=25.7 m, and maximum depth=252 m) than Alaska yearlings (x =16.6 m, 0=1.1 min, x = 63.4 m, 288 m), whereas Washington yearlings dived the longest and deepest (mean depth=39.4 m, mean duration=1.8 min, mean maximum depth=144.5 m, and maximum depth=328 m). Mean distance for 564 measured trips was 16.6 km; for sea lions ≤10 months of age, trip distance (7.0 km) was significantly less than for those >10 months of age (24.6 km). Mean trip duration for 10 of the 25 sea lions was 12.1 h; for sea lions ≤10 months of age, trip duration was 7.5 h and 18.1 h for those >10 months of age. We identified three movements types: long-range trips (>15 km and >20 h), short-range trips (<15 km and <20 h) during which the animals left and returned to the same site, and transits to other haul-out sites. Long-range trips started around 9 months of age and occurred most frequently around the assumed time of weaning, whereas short-range trips happened almost daily (0.9 trips/day, n=426 trips). Transits began as early as 7 months of age, occurred more often after 9 months of age, and ranged between 6.5 and 454 km. The change in dive characteristics coincided with the assumed onset of weaning. These yearling sea lion movement patterns and dive characteristics suggest that immature Steller sea lions are as capable of making the same types of movements as adults.

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.

Differential Expression of Immune Response Genes in Steller Sea Lions (Eumetopias jubatus): An Indicator of Ecosystem Health?

Characterization of the polygenic and polymorphic features of the Steller sea lion major histocompatibility complex (MHC) provides an ideal window for evaluating immunologic vigor of the population and identifying emergence of new genotypes that reflect ecosystem pressures. MHC genotyping can be used to measure the potential immunologic vigor of a population. However, since ecosystem-induced changes to MHC genotype can be slow to emerge, measurement of differential expression of these genes can potentially provide real-time evidence of immunologic perturbations. MHC DRB genes were cloned and sequenced using peripheral blood mononuclear leukocytes derived from 10 Steller sea lions from Southeast Alaska, Prince William Sound, and the Aleutian Islands. Nine unique DRB gene sequences were represented in each of 10 animals. MHC DRB gene expression was measured in a subset of six sea lions. Although DRB in genomic DNA was identical in all individuals, relative levels of expressed DRB mRNA was highly variable. Selective suppression of MHC DRB genes could be indicative of geographically disparate environmental pressures, thereby serving as an immediate and sensitive indicator of population and ecosystem health.

Kelp Forest Ecosystems: Biodiversity, Stability, Resilience and Future

Kelp forests are phyletically diverse, structurally complex and highly productive components of cold-water rocky marine coastlines. This paper reviews the conditions in which kelp forests develop globally and where, why and at what rate they become deforested. The ecology and long archaeological history of kelp forests are examined through case studies from southern California, the Aleutian Islands and the western North Atlantic, well-studied locations that represent the widest possible range in kelp forest biodiversity. Global distribution of kelp forests is physiologically constrained by light at high latitudes and by nutrients, warm temperatures and other macrophytes at low latitudes. Within mid-latitude belts (roughly 40-60degrees latitude in both hemispheres) well-developed kelp forests are most threatened by herbivory, usually from sea urchins. Overfishing and extirpation of highly valued vertebrate apex predators often triggered herbivore population increases, leading to widespread kelp deforestation. Such deforestations have the most profound and lasting impacts on species-depauperate systems, such as those in Alaska and the western North Atlantic. Globally urchin-induced deforestation has been increasing over the past 2-3 decades. Continued fishing down of coastal food webs has resulted in shifting harvesting targets from apex predators to their invertebrate prey, including kelp-grazing herbivores. The recent global expansion of sea urchin harvesting has led to the widespread extirpation of this herbivore, and kelp forests have returned in some locations but, for the first time, these forests are devoid of vertebrate apex predators. In the western North Atlantic, large predatory crabs have recently filled this void and they have become the new apex predator in this system. Similar shifts from fish- to crab-dominance may have occurred in coastal zones of the United Kingdom and Japan, where large predatory finfish were extirpated long ago. Three North American case studies of kelp forests were examined to determine their long history with humans and project the status of future kelp forests to the year 2025. Fishing impacts on kelp forest systems have been both profound and much longer in duration than previously thought. Archaeological data suggest that coastal peoples exploited kelp forest organisms for thousands of years, occasionally resulting in localized losses of apex predators, outbreaks of sea urchin populations and probably small-scale deforestation. Over the past two centuries, commercial exploitation for export led to the extirpation of sea urchin predators, such as the sea otter in the North Pacific and predatory fishes like the cod in the North Atlantic. The largescale removal of predators for export markets increased sea urchin abundances and promoted the decline of kelp forests over vast areas. Despite southern California having one of the longest known associations with coastal kelp forests, widespread deforestation is rare. It is possible that functional redundancies among predators and herbivores make this most diverse system most stable. Such biodiverse kelp forests may also resist invasion from non-native species. In the species-depauperate western North Atlantic, introduced algal competitors carpet the benthos and threaten future kelp dominance. There, other non-native herbivores and predators have become established and dominant components of this system. Climate changes have had measurable impacts on kelp forest ecosystems and efforts to control the emission of greenhouse gasses should be a global priority. However, overfishing appears to be the greatest manageable threat to kelp forest ecosystems over the 2025 time horizon. Management should focus on minimizing fishing impacts and restoring populations of functionally important species in these systems.

Bering Sea and Arctic Ocean Region, 1882 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Behring's Sea and Arctic Ocean : from surveys of the U.S. North Pacific Surveying Expedition in 1855, Commander John Rodgers U.S.N. commanding and from Russian and English authorities, J.C.P. de Kraft, commodore U.S.N. Hydrographer to the Bureau of Navigation ; compiled by E.R. Knorr ; drawn by Louis Waldecker. Corr. & additions to Jan. 1882. It was published by U.S. Navy, Hydrographic Office in 1882. Scale [ca. 1:4,400,000]. Covers the Bering Sea and Arctic Ocean region. The image inside the map neatline is georeferenced to the surface of the earth and fit to a non-standard 'Mercator' projection with the central meridian at 180 degrees west. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. Note: The central meridian of this map is not the same as the Prime Meridian and may wrap the International Date Line or overlap itself when displayed in GIS software. This map shows features such as drainage, cities and other human settlements, territorial boundaries, expedition routes, shoreline features, bays, harbors, islands, rocks, and more. Relief shown by hachures and spot heights. Depths shown by soundings. Includes drawing of Wrangel Island "as seen from Bark Nile of New London ... ; 15 to 18 miles distant". This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection and the Harvard University Library as part of the Open Collections Program at Harvard University project: Organizing Our World: Sponsored Exploration and Scientific Discovery in the Modern Age. Maps selected for the project correspond to various expeditions and represent a range of regions, originators, ground condition dates, scales, and purposes.

The Aleut language, the elements of Aleut grammar with a dictionary in two parts containing basic vocabularies of Aleut and English,

"Aleut-English dictionary, compiled by Richard Henry Geoghegan. A vocabulary of the Aleutian or Unangan language as spoken on the eastern Aleutian Islands and on the Alaska Peninsula, being a translation of the Russian, 'Slovarʹ aleutsko-lisʹevskago yazyka' or 'Dictionary of the Aleut-Fox language', by Ivan Veniaminov, 1834, with additions and annotations by the compiler": p. 89-124.

Experiments in the marking of seals and sea-lions

This report reviews experiments in the marking, for study purposes, of seals, sea-lions, and fur seals in the North Atlantic, North Pacific, and Antarctic regions. Also discussed are the results of studies of the northern fur seal, especially the series from 1940 to 1049 carried out by U.S. Government agents on the Pribilof Islands, Alaska. (PDF contains 38 pages)

Natural mortality rate, annual fecundity, and maturity at length for Greenland halibut (Reinhardtius hippoglossoides) from the northeastern Pacific Ocean

Mortality, fecundity, and size at maturity are important life history traits, and their interactions determine the evolution of life history strategies (Roff, 1992; Stearns, 1992; Charnov, 2002). These same traits are also important for population dynamics models (Hunter et al., 1992; Clark, 1999). It is increasingly important to accurately determine Greenland halibut (Reinhardtius hippoglossoides) life history traits and to correctly assess the status of its stocks because low recruitment or low biomass estimates have led to catch restrictions in the Bering Sea and Aleutian Islands (Ianelli et al.1), the Northeastern Arctic (Ådlandsvik et al., 2004), and the Northwest Atlantic (Bowering and Nedreaas, 2000).

Survey- and fishery-derived estimates of Pacific cod (Gadus macrocephalus) biomass: implications for strategies to reduce interactions between groundfish fisheries and Steller sea lions (Eumetopias jubatus)

Survey- and fishery-derived biomass estimates have indicated that the harvest indices for Pacific cod (Gadus macrocephalus) within a portion of Steller sea lion (Eumetopias jubatus) critical habitat in February and March 2001 were five to 16 times greater than the annual rate for the entire Bering Sea-Aleutian Islands stock. A bottom trawl survey yielded a cod biomass estimate of 49,032 metric tons (t) for the entire area surveyed, of which less than half (23,329 t) was located within the area used primarily by the commercial fishery, which caught 11,631 t of Pacific cod. Leslie depletion analyses of fishery data yielded biomass estimates of approximately 14,500 t (95% confidence intervals of approximately 9,000–25,000 t), which are within the 95% confidence interval on the fished area survey estimate (12,846–33,812 t). These data indicate that Leslie analyses may be useful in estimating local fish biomass and harvest indices for certain marine fisheries that are well constrained spatially and relatively short in duration (weeks). In addition, fishery effects on prey availability within the time and space scales relevant to foraging sea lions may be much greater than the effects indicated by annual harvest rates estimated from stock assessments averaged across the range of the target spec

Charles Henry Gilbert (1859-1928), Naturalist-in-Charge: the 1906 North Pacific Expedition of the Steamer Albatross

Fishery science pioneers often faced challenges in their field work that are mostly unknown to modern biologists. Some of the travails faced by ichthyologist and, later, fishery biologist Charles Henry Gilbert (1859-1928) during his service as Naturalist-in-Charge of the North Pacific cruise ofthe U.S. Bureau of Fisheries Steamer Albatross in 1906, are described here, as are accomplishments of the cruise. The vessel left San Francisco, Calif., on 3 May 1906, just after the great San Francisco earthquake, for scientific exploration of waters of the Aleutian islands, Bering Sea, Kamchatka, Sakhalin, and Japan, returning to San Francisco in December. Because the expedition occurred just after the war between Japan and Russia of 1904-05 floating derelict mines in Japanese waters were often a menace. Major storms caused havoc in the region, and the captain of the Albatross, Lieutenant Commander LeRoy Mason Garrett (1857-1906), U.S.N., was lost at sea, apparently thrown from the vessel during a sudden storm on the return leg of the cruise. Despite such obstacles, Gilbert and the Albatross successfully completed their assigned chores. They occupied 339 dredging and 48 hydrographic stations, and discovered over 180 new species of fishes and many new species of invertebrates. The expedition's extensive biological collections spawned over 30 descriptive publications, some of which remain today as standards of knowledge.

The dusky rockfishes (Teleostei: Socrpaeniformes) of the North Pacific Ocean: resurrection of Sebastes variabilis (Pallas, 1814) and a redescription of Sebastes ciliatus (Tilesius, 1813)

The dusky rockfish (Sebastes ciliatus) of the North Pacific Ocean has been considered a single variable species with light and dark forms distributed in deep and shallow water, respectively. These forms have been subjected to two distinct fisheries separately managed by federal and state agencies: the light deep form is captured in the offshore trawl fishery; the dark shallow form, in the nearshore jig fishery. The forms have been commonly recognized as the light dusky and dark dusky rockfishes. From morphological evidence correlated with color differences in some 400 specimens, we recognize two species corresponding with these color forms. Sebastes ciliatus (Tilesius) is the dark shallow-water species found in depths of 5−160 m in the western Aleutian Islands and eastern Bering Sea to British Columbia. The name Sebastes variabilis (Pallas) is resurrected from the synonymy of S. ciliatus to apply to the deeper water species known from depths of 12−675 m and ranging from Hokkaido, Japan, through the Aleutian Islands and eastern Bering Sea, to Oregon. Sebastes ciliatus is uniformly dark blue to black, gradually lightening on the ventrum, with a jet black peritoneum, a smaller symphyseal knob, and fewer lateral-line pores compared to S. variabilis. Sebastes variabilis is more variable in body color, ranging from light yellow to a more usual tan or greenish brown to a nearly uniform dark dorsum, but it invariably has a distinct red to white ventrum. Synonymies, diagnoses, descriptions, and geographic distributions are provided for each species.

Magma Evolution in the Primitive, Intra-oceanic Tonga Arc: Rapid Petrogenesis of Dacites at Fonualei Volcano

Fonualei is unusual amongst subaerial volcanoes in the Tonga arc because it has erupted dacitic vesicular lavas, tuffs and phreomagmatic deposits for the last 165 years. The total volume of dacite may approach 5 km(3) and overlies basal basaltic andesite and andesite lavas that are constrained to be less than a few millennia in age. All of the products are crystal-poor and formed from relatively low-viscosity magmas inferred to have had temperatures of 1100-1000 degrees C, 2-4 wt % H2O and oxygen fugacities 1-2 log units above the quartz-fayalite-magnetite buffer. Major and trace element data, along with Sr-Nd-Pb and U-Th-Ra isotope data, are used to assess competing models for the origin of the dacites. Positive correlations between Sc and Zr and Sr rule out evolution of the within-dacite compositional array by closed-system crystal fractionation of a single magma batch. An origin by partial melting of lower crustal amphibolites cannot reproduce these data trends or, arguably, any of the dacites either. Instead, we develop a model in which the dacites reflect mixing between two dacitic magmas, each the product of fractional crystallization of basaltic andesite magmas formed by different degrees of partial melting. Mixing was efficient because the two magmas had similar temperatures and viscosities. This is inferred to have occurred at shallow (2-6 km) depths beneath the volcano. U-Th-Ra disequilibria in the basaltic andesite and andesite indicate that the parental magmas had fluids added to their mantle source regions less than 8 kyr ago and that fractionation to the dacitic compositions took less than a few millennia. The 165 year eruption period for the dacites implies that mixing occurred on a similar timescale, possibly during ascent in conduits. The composition of the dacites renders them unsuitable candidates as contributors to average continental crust.