Energy Density and Length of Juvenile Pink Salmon Oncorhynchus gorbuscha in the Eastern Bering Sea from 2004 to 2007: a Period of Relatively Warm and Cool Sea Surface Temperatures

Abstract

Juvenile pink salmon (Oncorhynchus gorbuscha) were examined in the eastern Bering Sea from 2004 to 2007 to assess the influence of ocean temperature on whole body energy content (WBEC), length, and diet. Fish were collected during the United States Bering-Aleutian Salmon International Study (U.S. BASIS) surveys in the eastern Bering Sea. Warmer spring and summer sea surface temperatures prevailed from 2004 to 2005 on the eastern Bering Sea shelf, whereas cooler spring and summer sea surface temperatures occurred from 2006 to 2007. Juvenile pink salmon changed diet between the warm and cool years. Walleye pollock Theragra chalcogramma dominated the diet (> 50% wet mass) in warm years, while walleye pollock were nearly absent from the diet in cool years. Juvenile pink salmon lengths were significantly longer in warm years but WBEC was significantly lower. We interpret our results to indicate that length is not always a reliable measure of energy status.