Seasonal and interannual variation in the allometry of energy allocation.in juvenile striped bass

Survival rates during the first winter of life are strongly size dependent and variable in many temperate fish populations. Starvation is often implicated as the cause of size-dependent first-winter mortality, and interannual variation in energy accumulation and the allocation between growth and storage is a likely source of variability. We examined these processes in young-of-the-year Hudson River striped bass Morone saxatilis, which are known to experience size-selective winter mortality and a winter energy deficit. Neutral-lipid and lean-tissue masses were determined for fish of five consecutive year classes collected through the first year of life. Differences in scaling relationships between body length and neutral-lipid and lean-tissue mass were used to infer patterns of resource allocation. Lipid reserves scaled isometrically with body length in summer but increased at a greater rate than did body length in autumn and winter. Lean-tissue allometries were less variable but followed a similar seasonal cycle. Allometric slopes were homogeneous across years, but significant interannual variation in length-specific lipid content and lean-tissue mass in the later half of the growing season indicated variable allocation patterns. During winter, up to 21% of total energy content and 50% of neutral-lipid stores were depleted. The-results indicate that energy allocation patterns result from interactions among season, ontogenetic stage, and body size. The variation in growth, allocation, and severity of the winter energy deficit likely interact to determine first-winter survival.