CHRISTOPHER D. SMITH AND GENE R. WILDE, Department of Range, Wildlife, and Fisheries Management, Texas Tech University, Lubbock, Texas 79409, USA

Food deprivation in larval and post-larval fishes has long been thought to be a cause of year class failure. Methods to detect starvation in larval fishes have been applied to several marine species, but very few freshwater species. We developed an index of nutritional status for post-larval largemouth bass Micropterus salmoides based on morphological changes during food deprivation. Bass were either fed or unfed. A truss network, along with additional measurements of standard length and body depth at the anal vent, was applied to 163 largemouth bass, 8-13 mm. A size-free discriminant function analysis was used to distinguish between fed and unfed largemouth bass. Mean discriminant scores for fed and unfed fish were significantly different (P < 0.01). Three characters, anchored at the insertion point of the pelvic fin and the body depth at the anal vent, were most capable in discriminating between fed and unfed bass. Fed fish had significantly higher (P < 0.01) ratios of the four measurements to standard length. Any of these ratios allows nutritional status of larval largemouth bass to be quickly and easily determined.