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

Abstract

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.