INTRAANNUAL AND INTERANNUAL VARIATION IN THE RELATIVE CONDITION AND PROXIMATE BODY-COMPOSITION OF ARCTIC CISCOES FROM THE PRUDHOE BAY-REGION OF ALASKA

Weight and length data collected during the summers from 1984 through 1994 were used to examine the seasonal life history strategy of Arctic ciscoes Coregonus autumnalis collected from Prudhoe Bay, Alaska. Diff erences in observed and predicted weight were used to determine if con dition increases during the summer feeding season when energy reserves are accumulated and decreases during winter when energy reserves are depleted. Data from proximate body analyses of lipid and protein conte nt collected from 1991 to 1993 also were examined. Condition was index ed as residual values generated from a whole population least-squares regression of log(e)-transformed weight and length data. For data pool ed by individual year-classes, we tested the conceptual hypothesis tha t mean residual value, mean lipid content, and mean protein content in creased during summer and decreased during winter. For the 12 year-cla sses examined, concurrent mean residual values supported our conceptua l hypothesis in 61 of 76 instances (P < 3.0 E-7), but for mean lipid c ontent and mean protein content, our hypothesis was supported in only 13 of 21 cases (P = 0.14) and had to be rejected. However, 6 of the 8 failures in lipid change and 7 of 13 failures in residual change were associated with summer 1991. Data suggested that Arctic ciscoes did no t accumulate lipid reserves during summer 1991 and that relative condi tion analysis detected this anomaly in nearly every year-class examine d. Results were therefore consistent with a strategy of accumulating e nergy reserves in summer and depleting those reserves to survive the A rctic winter.