Variation in the distribution of walleye pollock (Theragra chalcogramma) with temperature and implications for seasonal migration

• Main Authors: Kotwicki, Stan, Buckley, Troy W., Honkalehto, Taina, Walters, Gary
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2005
• Subjects: Biology; Ecology; Fisheries; Bering Sea; Theragra chalcogramma
• Online Access: http://aquaticcommons.org/9016/; http://fishbull.noaa.gov/1034/kotw.pdf; http://aquaticcommons.org/9016/1/kotw.pdf

Aspects of the feeding migration of walleye pollock (Theragra chalcogramma) in the eastern Bering Sea (EBS) were investigated by examining the relationship between temperatures and densities of fish encountered during acoustic and bottom trawl surveys conducted in spring and summer between 1982 and 2001. Bottom temperature was used as an indicator of spring and summer warming of the EBS. Clusters of survey stations were identified where the density of walleye pollock generally increased or decreased with increasing water temperature. Inferences about the direction and magnitude of the spring and summer feeding migration were made for five length categories of walleye pollock. Generally, feeding migrations appeared to be northward and shoreward, and the magnitude of this migration appeared to increase with walleye pollock size up to 50 cm. Pollock larger then 50 cm showed limited migratory behavior. Pollock may benefit from northward feeding migrations because of the changes in temperature, zooplankton production, and light conditions. Ongoing climate changes may affect pollock distribution and create new challenges for pollock management in the EBS.