Seasonal and Geographic Variation in Condition of Juvenile Walleye Pollock in the Western Gulf of Alaska

Abstract Body length, length-specific weight, and length-specific whole-body energy content (WBEC) of juvenile walleye pollock Theragra chalcogramma were examined for evidence of seasonal and geographic variation. Identifying the impact of winter on these measures of fish condition was of primary concern, but we also sought to determine whether condition varies among different geographic regions. The 2000 year-class of walleye pollock was sampled in the western Gulf of Alaska during four seasons (the autumn of 2000 and the winter, summer, and autumn of 2001), and the study area was divided into three regions (Kodiak, Semidi, and Shumagin). In each region, length-specific weight decreased from autumn to winter by up to 17%, subsequently increasing into the summer by 13–20%. Significant seasonal changes in length-specific WBEC varied by region but reflected the same trends as length-specific weight. Walleye pollock from the Kodiak region were in better condition than those from other regions, as evidenced b...