Alaska Fishery Research Bulletin Issues, Vol.10 No. 2 - Winter 2003

The Long-Term Outlook for Salmon Returns to Alaska

Milo D. Adkison and Bruce P. Finney - Vol. 10(2):83-94. 2003.

With the exception of some western Alaska stocks, Alaska's salmon populations are numerically healthy. However, even fisheries on abundant stocks are suffering economically due to sharp declines in the value of the catch. The abundance of Alaskan salmon stocks has fluctuated greatly, both in modern times and prehistorically. These fluctuations are thought to be caused by multi-decadal changes in environmental conditions over large areas that affect many other species as well as salmon. Forecasts of salmon returns are not very reliable, and the potential for significant improvement in their accuracy is low in the short term. A viable fishing industry must be able to adapt to dramatic, persistent, and unanticipated changes in harvest levels. Nonetheless, Alaska's salmon stocks should continue to produce healthy harvests for the foreseeable future, barring significant damage to their habitat either via local activities or global warming.

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Critical Elements of Kvichak River Sockeye Salmon Management

Lowell F. Fair - Vol. 10(2):95-103. 2003.

The Kvichak River of Bristol Bay, Alaska, is one of the world's largest sockeye salmon producing systems. This paper reviews and documents past management practices for the Kvichak River sockeye salmon. Fishery harvests are managed to meet a biological spawning escapement goal set by the State of Alaska and regulated using management plans adopted by the Alaska Board of Fisheries. Several measures of inseason run abundance are used to determine time and area of fishery openings that allow the escapement goal to be met and ensure that escapement is obtained throughout the run. Returns to the Kvichak River have been relatively small for seven of the past eight years. To hasten rebuilding of this run, the Alaska Board of Fisheries implemented additional management plans in 2001 that limit incidental harvests of Kvichak River sockeye salmon. These restrictions were effective in decreasing the catch of Kvichak River sockeye salmon, but total escapements achieved in 2002 and 2003 were still below the lower end of the escapement goals thought to produce the greatest catches in the future. While small runs and resulting low escapement levels have restricted commercial and sport fishery harvests, sustainability of this sockeye salmon run does not appear threatened at this time. The escapement goal for the Kvichak River is set at a level that provides the greatest potential for obtaining maximum sustained yield. While it is unlikely that escapements below the goal will provide high yields, past performance of low escapements has demonstrated that the Kvichak River run is still sustainable and has the capacity to produce large returns when conditions are favorable.

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Biological and Spatial Characteristics of the Weathervane Scallop Patinopecten Caurinus at Chiniak Gully in the Central Gulf of Alaska

Michele M. Masuda and Robert P. Stone - Vol. 10(2):104-118. 2003.

A manned submersible was used to collect biological and behavioral information on a deepwater population of weathervane scallops Patinopecten caurinus near Kodiak Island in the central Gulf of Alaska. Counts and positions of weathervane scallops and 3 additional species groups (anemones [Cribrinopsis fernaldi and Metridium senile], sunflower sea stars Pycnopodia helianthoides, and sea whips [Protoptilum sp. and Halipteris willemoesi]) along 20 fixed transects were compiled from video footage of the seafloor. The study site encompassed areas open to bottom trawling and scallop dredging and areas closed for 11 and 12 years. Statistical methods of circular tests, neighbor K analysis for one-dimensional data, analysis of variance, and Spearman rank correlation coefficient were used to assess weathervane scallop orientation, spatial characteristics, differences in abundance and size distributions between open and closed areas, and faunal associations. Orientation of weathervane scallops was directed with most oriented towards the strongest, prevailing bottom currents or the reciprocal, weaker currents. Adult weathervane scallops were aggregated in patch lengths ranging from less than 10 m to over 700 m. In 1999 only, the open area had higher prerecruit abundance relative to recruit abundance than the closed area. Weathervane scallop density (number of scallops m-2) was not significantly lower in the open than in the closed area. There was some evidence of positive spatial associations between adult weathervane scallops and both large sea whips and anemones, and negative spatial association between adult weathervane scallops and sunflower sea stars. Juvenile weathervane scallops exhibited positive spatial association with anemones. Weathervane scallop density tended to be high in areas of high sea whip density and low in areas of high sunflower sea star density.

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Effect of Parasitism by Philonema agubernaculum (Nematoda: Philometridae) on the Ability of Dolly Varden to Capture Prey in Fresh and Salt Water

Adam Moles - Vol. 10(2):119-123. 2003.

Dolly Varden Salvelinus malma parasitized by a single nematode Philonema agubernaculum had significantly reduced ability to capture pink salmon fry Oncorhynchus gorbuscha in laboratory tests. Predator-prey trials, in which half the Dolly Varden were parasitized, were conducted in fresh water and salt water. Unparasitized Dolly Varden in fresh water captured a mean of 64% of the pink salmon during the test period and unparasitized Dolly Varden in salt water captured 61% of their available prey in the time allotted. In contrast, parasitized Dolly Varden in fresh water captured 32% of their prey as opposed to 29% in salt water. Nematode parasitism has the potential to reduce the foraging ability of Dolly Varden in the laboratory under conditions of abundant food, but the broader ecological consequences remain unclear.

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Pop-up Archival Transmitting (PAT) Tags: A Method to Investigate the Migration and Behavior of Pacific Halibut Hippoglossus stenolepis in the Gulf of Alaska

Andrew C. Seitz, Derek Wilson, Brenda L. Norcross and Jennifer L. Nielsen - Vol. 10(2):124-136. 2003.

Pop-up archival transmitting (PAT) tags provide a fisheries-independent method of collecting environmental preference data (depth and ambient water temperature) and migration distance. In this study, we evaluate the use of pop-up archival transmitting tags as a method to investigate demersal fish. We report the results from eight pop-up archival transmitting tagged Pacific halibut Hippoglossus stenolepis (from 107 to 165 cm FL) that were released in and around Resurrection Bay, Alaska. Commercial fishermen recovered three tags, while five tags transmitted data to Argos satellites. Horizontal migration was not consistent among fish as four Pacific halibut remained in the vicinity of release while the other four traveled up to 358 km from the release site. Vertical movement was not consistent among fish or over time; however, they spent most of their time at depths of 150 to 350 m. The minimum and maximum depths reached by any of the Pacific halibut were 2 m and 502 m, respectively. The fish preferred water temperatures of approximately 6°C, but experienced temperatures between 4.3 and 12.2°C. Light attenuation with depth prevented geolocation software and light sensing hardware from accurately estimating geoposition for the majority of days. The methods, adapted from investigations on large pelagic fish, proved to be effective for studying Pacific halibut in the northern Gulf of Alaska. PAT tags allowed us to obtain high accuracy locations of the fish at the end of the tag deployments as well as preliminary data to identify approximate seasonal locations and to characterize their depth and temperature characteristics. By using PAT tags, we will be able to ensure tag returns during the winter season (which is closed to fishing) and gain valuable biological information even if fish migrate large distances or to unexpected locations.

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Growth of Male Tanner Crabs Chionoecetes bairdi in a Southeast Alaska Estuary

Robert P. Stone, Michele M. Masuda, and John E. Clark - Vol. 10(2):137-148. 2003.

Growth of male Tanner crabs Chionoecetes bairdi from a glacial Southeast Alaska estuarine population was studied during 1999 and 2000. Premolt crabs were collected in situ by scuba divers and held in the laboratory until molting occurred (less than or equal to 33 d). An interannual difference in growth was not found, but growth was significantly greater (2.3% to 6.2%) than that observed for Kodiak Island area crabs during the 1970s. Current management of Tanner crabs throughout Alaska is based on growth estimated for Kodiak Island crabs in the 1970s. A significant change in allometric growth occurred at 96.5 mm carapace width. Growth was reduced for crabs held in the laboratory >13 d, crabs missing three or more premolt limbs, and crabs missing two or more postmolt limbs. Crabs attained large-claw status over a wide size range (approximately 125.0 to 178.9 mm postmolt carapace width) and among large-clawed crabs a percent increase in chela height was not associated with a percent decrease in growth. Growth data indicated that the majority (53% to 70%) of Tanner crabs harvested in the Southeast Alaska commercial fishery during most years were newly recruited to the fishery.

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