MEPS 503:111-122 (2014)  -  DOI: https://doi.org/10.3354/meps10736

The spatial distribution of euphausiids and walleye pollock in the eastern Bering Sea does not imply top-down control by predation

Patrick H. Ressler*, Alex De Robertis, Stan Kotwicki

NOAA, National Marine Fisheries Service, Alaska Fisheries Science Center, 7600 Sand Point Way NE, Seattle, Washington 98115, USA
*Corresponding author:

ABSTRACT: Although euphausiids of the genus Thysanoessa (‘krill’) are a key zooplankton taxon in the Bering Sea ecosystem, the processes controlling variation in the standing stock of these animals are not well understood. Both forcing by temperature (‘bottom-up’) and predation (‘top-down’) have been proposed. If strong top-down forcing were present, a negative relationship would be expected between the standing stock of euphausiids and that of walleye pollock Gadus chalcogrammus, their single most important predator in the Bering Sea. We developed multiple regression models using survey data collected over several years to test the hypothesis of a negative relationship between local (mesoscale) densities of these animals. We used the models to evaluate the relative importance of pollock biomass and water temperature in predicting euphausiid biomass, and found that temperature was a far better predictor, a result that is not consistent with dominant top-down control of euphausiids by pollock predation.


KEY WORDS: Alaska · Bering Sea · Walleye pollock · Theragra chalcogramma · Euphausiids · Thysanoessa · Gadus chalcogrammus · Acoustics · Top-down · Bottom-up · GAM


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Cite this article as: Ressler PH, De Robertis A, Kotwicki S (2014) The spatial distribution of euphausiids and walleye pollock in the eastern Bering Sea does not imply top-down control by predation. Mar Ecol Prog Ser 503:111-122. https://doi.org/10.3354/meps10736

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