RELATIONSHIP OF RELATIVE WEIGHT (WR) TO PROXIMATE COMPOSITION OF JUVENILE STRIPED BASS AND HYBRID STRIPED BASS

The relative weight (W(r)) index is commonly used to assess fish condition. However, little is known about the relationship of W(r) to physiological condition. Whole-body proximate analysis quantifies the general chemical composition of fish but is impractical and too costly for large-scale application to natural populations. Relative weight may offer an alternative method to estimate body composition. We raised juvenile striped bass Morone saxatilis and hybrid striped bass M. saxatilis female x M. chrysops male under controlled conditions for a 12-week period and then determined their proximate compositions. Analysis of relationships between W(r) and proximate components indicated that W(r) may be used for estimating body composition and gross energy in juvenile striped bass and hybrid striped bass; W(r) was correlated with percent crude fat, crude protein, ash, visceral fat, and ash-free dry-weight gross energy. Additionally, W(r) was correlated with relative growth and the change in total length for the experimental period. Reserve energy (visceral fat) predicted from W(r) may provide a measure of overwintering fitness and suitability of juvenile striped bass and hybrid striped bass for stocking.