The relative influence of temperature and size-structure on fish distribution shifts: A case-study on Walleye pollock in 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.

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Interannual differences in the diet composition and stomach fullness indexes of Walleye Pollock during the feeding period in the Anadyr-Navarinsky region of the Bering Sea

Trudy VNIRO ◽

10.36038/2307-3497-2021-183-61-74 ◽

2021 ◽

Vol 183 ◽

pp. 61-74

Author(s):

S.E. Frenkel ◽

◽

E.N. Kuznetsova ◽

A.V. Presnyakov ◽

A.I. Glubokov ◽

...

Keyword(s):

Bering Sea ◽

Diet Composition ◽

Walleye Pollock ◽

Stomach Fullness ◽

Feeding Period ◽

The Bering Sea

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Spatial modeling of Bering Sea walleye pollock with integrated age-structured assessment models in a changing environment

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2013-0020 ◽

2013 ◽

Vol 70 (9) ◽

pp. 1402-1416 ◽

Cited By ~ 24

Author(s):

Peter-John F. Hulson ◽

Terrance J. Quinn ◽

Dana H. Hanselman ◽

James N. Ianelli

Keyword(s):

Climate Change ◽

Bering Sea ◽

Walleye Pollock ◽

Spatially Explicit ◽

Parameter Estimates ◽

Effective Sample Size ◽

Climate Change Effects ◽

Spatially Explicit Models ◽

Distribution Shifts ◽

Age Structured

Climate change may affect the spatial distribution of fish populations in ways that would affect the accuracy of spatially aggregated age-structured assessment models. To evaluate such scenarios, spatially aggregated models were compared with spatially explicit models using simulations. These scenarios were based on hypothetical climate-driven distribution shifts and reductions in mean recruitment of walleye pollock (Gadus chalcogrammus) in the eastern Bering Sea. Results indicate that biomass estimates were reasonably accurate for both types of estimation models and precision improved with the inclusion of tagging data. Bias in some aggregated model scenarios could be attributed to unaccounted-for process errors in annual fishing mortality rates and was reduced when estimating effective sample size or time-varying selectivity. Spatially explicit models that allow estimation of variability in movement and ontogenetic parameters (specified as a random walk process) were shown to be feasible, whereas models that misspecified ontogenetic movement and climate change effects resulted in biased biomass and movement parameter estimates. These results illustrate that more complex models may characterize processes better but may be less robust for management advice.

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The power of acoustics in ocean observing systems: A case study in the Bering Sea

The Journal of the Acoustical Society of America ◽

10.1121/1.4755028 ◽

2012 ◽

Vol 132 (3) ◽

pp. 1915-1915

Author(s):

Jennifer L. Miksis-Olds ◽

Laura E. Madden

Keyword(s):

Bering Sea ◽

Ocean Observing ◽

Ocean Observing Systems ◽

The Bering Sea ◽

Observing Systems

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

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2012-0265 ◽

2013 ◽

Vol 70 (6) ◽

pp. 841-853 ◽

Cited By ~ 18

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.

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