Regional, interannual and size-related variation of age 0 year walleye pollock whole body energy content around the Pribilof Islands, Bering Sea

Mean whole energy content (Ewb) of age 0 year walleye pollock Theragra chalcogramma was 19·928 KJ g 1 dry mass in 3943 fish collected from different habitats around the Pribilof Islands frontal structure, south-east Bering Sea, during September 1994–1996 and 1999. It varied, however, with habitat type. Fish residing offshore had higher Ewb than fish residing inshore of the frontal regions. Age 0 year walleye pollock Ewb changed in a non-linear fashion with fish size, with larger juveniles typically having higher Ewb. Size thresholds were identified at which the relationship between age 0 year walleye pollock Ewb and LS changed. One such threshold was found at 46 mm where Ewb reached a local minimum. Another threshold was found at 80 mm beyond which Ewb tended to remain constant with size. Overall mass-length and Ewb-length residuals were highly correlated with each other (r=0·73, P 0·0001). The slope of the regression, however, was higher for smaller fish. Possible mechanisms are proposed to explain the observed ontogenetic variation in nutritional status and the role of age 0 year walleye pollock late summer Ewb on survival over their first critical winter of life. 2002 The Fisheries Society of the British Isles