scholarly journals Feeding selectivity of larval walleye pollock Theragra chalcogramma in the oceanic domain of the Bering Sea

1995 ◽  
Vol 120 ◽  
pp. 1-10 ◽  
Author(s):  
N Hillgruber ◽  
LJ Haldorson ◽  
AJ Paul
Keyword(s):  
Bering Sea ◽  
Walleye Pollock ◽  
Theragra Chalcogramma ◽  
Feeding Selectivity ◽  
Walleye Pollock Theragra Chalcogramma ◽  
The Bering Sea ◽  
Oceanic Domain

Relating trends in walleye pollock (Theragra chalcogramma) abundance in the Bering Sea to environmental factors

1995 ◽  
Vol 52 (2) ◽  
pp. 369-380 ◽  
Author(s):  
Gordon Swartzman ◽  
Emily Silverman ◽  
Neal Williamson
Keyword(s):  
Water Column ◽  
Bering Sea ◽  
Walleye Pollock ◽  
Additive Models ◽  
Theragra Chalcogramma ◽  
Thermocline Depth ◽  
Depth Range ◽  
Walleye Pollock Theragra Chalcogramma ◽  
Shelf Slope ◽  
The Bering Sea

Generalized additive models (GAM), a nonparametric regression method with less restrictive statistical assumptions than traditional regression methods, were used to model the trend in mean abundance of Bering Sea walleye pollock (Theragra chalcogramma) as a function of ocean environmental conditions including water column depth, temperature at 50 m, and depth of the thermocline. Acoustic survey data collected in the summers of 1988 and 1991 were used to test these relationships. In both surveys, mean walleye pollock abundance was highest in areas having a 70–130 m depth range and where the 50-m temperature was close to 2.5 °C. Thermocline depth, while not itself significant, had a significant effect on walleye pollock abundance through interactions with both bottom depth and temperature at 50 m. Walleye pollock in the top 50 m of the water column (mostly juveniles) were influenced differently by temperature and thermocline depth than the adult walleye pollock, which were generally deeper in the water column. The depth, temperature, and thermocline preferences of walleye pollock are hypothesized to be linked to food availability which is, in turn, related to temperature regimes or fronts along the Bering Sea shelf slope.

Climatic and economic drivers of the Bering Sea walleye pollock (Theragra chalcogramma) fishery: implications for the future

2013 ◽  
Vol 70 (6) ◽  
pp. 841-853 ◽  
Author(s):  
Alan C. Haynie ◽  
Lisa Pfeiffer
Keyword(s):  
Climate Change ◽  
Bering Sea ◽  
Climate Models ◽  
Walleye Pollock ◽  
Spatial And Temporal Variation ◽  
Theragra Chalcogramma ◽  
Climate Change Scenarios ◽  
Walleye Pollock Theragra Chalcogramma ◽  
The Impact ◽  
The Bering Sea

This paper illustrates how climate, management, and economic drivers of a fishery interact to affect fishing. Retrospective data from the Bering Sea walleye pollock (Theragra chalcogramma) catcher–processer fishery were used to model the impact of climate on spatial and temporal variation in catch and fishing locations and make inferences about harvester behavior in a warmer climate. Models based on Intergovernmental Panel on Climate Change scenarios predict a 40% decrease in sea ice by 2050, resulting in warmer Bering Sea temperatures. We find that differences in the value of catch result in disparate behavior between winter and summer seasons. In winter, warm temperatures and high abundances drive intensive effort early in the season to harvest earlier-maturing roe. In summer, warmer ocean temperatures were associated with lower catch rates and approximately 4% less fishing in the northern fishing grounds, contrary to expectations derived from climate-envelope-type models that suggest fisheries will follow fish poleward. Production-related spatial price differences affected the effort distribution by a similar magnitude. However, warm, low-abundance years have not been historically observed, increasing uncertainty about future fishing conditions. Overall, annual variation in ocean temperatures and economic factors has thus far been more significant than long-term climate change-related shifts in the fishery's distribution of effort.

Mitochondrial DNA Analysis of Walleye Pollock, Theragra chalcogramma, from the Eastern Bering Sea and Shelikof Strait, Gulf of Alaska

1992 ◽  
Vol 49 (2) ◽  
pp. 319-326 ◽  
Author(s):  
Timothy J. Mulligan ◽  
Robert W. Chapman ◽  
Bonnie L. Brown
Keyword(s):  
Mitochondrial Dna ◽  
Bering Sea ◽  
Dna Analysis ◽  
Gulf Of Alaska ◽  
Fishing Effort ◽  
Walleye Pollock ◽  
Theragra Chalcogramma ◽  
Eastern Bering Sea ◽  
Walleye Pollock Theragra Chalcogramma ◽  
The Bering Sea

Increased fishing effort in the international waters of the Aleutian Basin has focused much interest on defining the stock structure of walleye pollock, Theragra chalcogramma, in the Bering Sea. Variation in mitochondrial DNA (mtDNA) was examined via restriction endonuclease digestions in 168 walleye pollock from three areas in the eastern Bering Sea and from Shelikof Strait, Gulf of Alaska. Nine endonucleases produced variant restriction patterns both within and among populations. A total of 50 restriction sites were revealed along the mtDNA molecule. Two dominant genotypes were found in 39 and 21 individuals, respectively. Fifty-one genotypes (78% of the total) were represented by a single specimen. Clustering of genetic distances suggests the existence of several walleye pollock stocks in the Bering Sea and Gulf of Alaska. Genetic divergence among stocks may be related to the prevailing current patterns found in these areas.

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