Growth and Survival of Hybrid Sunfish Larvae in the Laboratory under Different Feeding and Temperature Regimes

Abstract

The objective of this study was to determine the effects of different feeding protocols and temperatures on growth and survival of hybrid fry of female green sunfish Lepomis cyanellus × male bluegill L. macrochirus. At swim-up (5–6 d posthatch), we divided larvae into three different treatments: feedings of brine shrimp Artemia franciscana for 0, 3, or 7 d followed by a 3-d weaning period to a commercial diet. We monitored fish growth and survival through 28 d posthatch. Significant differences in growth were not evident at 28 d posthatch, but survival in the 7-d treatment (mean, 37%; SE, 2.6%) was significantly higher than that in the other treatments. In a second experiment comparing three different temperatures (19, 21, and 24°C) and two feeding regimes (live brine shrimp for 3 and 7 d before weaning to commercial feed), temperature regimes did not significantly affect growth. At 28 d posthatch, larvae fed brine shrimp for 7 d were significantly longer than those fed for 3 d. At 21°C and 24°C, larvae fed brine shrimp for 7 d were significantly heavier than those fed for 3 d. Within the specific feeding regimes, larvae cultured at 21°C were significantly heavier than those at 19°C and 24°C. Survival (28% to 41%) did not differ significantly among the treatments. The initial brine shrimp feeding regime affects fish growth more than do temperatures within the 19–24°C range. When using brine shrimp to culture larval green sunfish × bluegill hybrids for at least 7 d, survival rates of approximately 40% can be expected.