FALL AND SPRING SOMATIC ENERGY CONTENT FOR ALASKAN PACIFIC HERRING (CLUPEA-PALLASI VALENCIENNES 1847) RELATIVE TO AGE, SIZE AND SEX

During the fall of 1995 and spring of 1996, the whole body energy cont ent (WBEC) of Pacific herring (Clupea pallasi Valenciennes 1847) from Prince William Sound, Alaska, was examined. Somatic energy (kJ.g(-1) w et wt.) exhibited a wide range of values relative to fish length. In t he fall young of the year (YOY) recruits had an average of 5.7 kJ.g(-1 ) wet wt. for whole body samples vs. 8.0 for age 1 and 9.4-10.2 kJ.g(- 1) for fish of ages 2 to 7. The following spring the 1995 year class w hich had just survived their first winter averaged 4.4 kJ.g(-1) wet wt . for somatic samples, and age 1 fish had similar values, while herrin g ages 2 to 7 had WBEC > 5 kJ.g(-1). The difference in somatic energy content between adult male and female fish captured in fall and again in the spring just prior to spawning, was about 4 kJ.g(-1) wet wt., or about a 40% change. The difference in mean values for somatic energy content for YOY herring was only about 1.4 kJ.g(-1) suggesting either the recruits ate more food during the winter than the adults, had lowe r energetic needs, or only those with higher than average energy store s survived the winter. The fall measures of WBEC showed the YOY and ag e 1 fish stored markedly less energy to over-winter than older herring . Thus, energetically the recruiting year class, and those entering th eir second winter, are the most at risk of over-winter mortality. (C) 1998 Elsevier Science B.V.