Schooling pattern of eastern Bering Sea walleye pollock and its impact on fishing behavior
نویسندگان
چکیده
Walleye pollock (Theragra chalcogramma) form persistent midwater and near-bottom schools in the daytime during the winter spawning season in the eastern Bering Sea (EBS). Two spawning areas in the EBS, north of Unimak Island and near the Pribilof Islands, are also the main fishing grounds. To study the schooling pattern of pollock and its impact on fishing behavior on these two fishing grounds, a principal component analysis with instrumental variables (PCAIV) was done using acoustic and observer data from 2003 and 2005. Significant differences between the school descriptors made it possible to distinguish schooling patterns among areas and years. The harvester searched for fish aggregations which were caught in a different manner when the schooling pattern changed. School density had more effect than school size on fishing behavior. Aggregations were less dense in 2003 compared to 2005, and the harvester tended to fish with higher speed and longer tows when it encountered less dense aggregations.
منابع مشابه
Spatial and Temporal Variability in Size at Maturity of Walleye Pollock in the Eastern Bering Sea
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