Minimizing Time Fed Rotifers Maximizes Hybrid Striped Bass Larval Growth in Recirculating Aquaculture Systems

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AbstractHybrid Striped Bass (HSB; White Bass Morone chrysops × Striped Bass M. saxatilis) represent a valuable sector of the U.S. aquaculture industry. Despite their commercial importance, one factor limiting the growth of the HSB industry is the lack of refined methods to rear larvae in tanks, including the lack of knowledge about optimal rearing conditions, feeding behavior, and efforts to reduce the time larvae spend utilizing live foods. Four‐day‐old HSB larvae were stocked into two recirculating aquaculture systems (72.0–73.9 larvae/L) maintained at 18°C and 26°C. Larvae were fed three times daily with either rotifers Brachionus plicatilis (60 rotifers · mL−1 · tank−1 · d−1) or brine shrimp Artemia sp. (12 Artemia · mL−1 · tank−1 · d−1) according to the designated replicated treatment for 2–12 d in 2‐d increments where larvae were progressively weaned from rotifers onto Artemia. The number of days fed rotifers (DFR) had no significant effect on survival of larvae reared at either 18°C (46.6%) or 26°C (30.2%). However, there was a significant difference in larval survival between the two temperatures. Larvae were measured at the conclusion of the study, and those reared at 18°C were shorter (8.00 mm TL) than those reared at 26°C (9.59 mm TL); TL and body depth of larvae varied significantly among treatments by temperature, DFR, and their interaction. These results demonstrate that minimizing the time spent feeding on rotifers maximized the growth of HSB larvae. Results also indicate that Artemia is a suitable diet for 6‐d‐old larval HSB and that the fish can easily be weaned from rotifers at both optimum (26°C) and suboptimum (18°C) culture temperatures while maintaining suitable growth. Notably, this was achieved with no significant drop in survival. Additional research is needed to optimize Artemia nauplius feeding regimes to minimize the time for which HSB must be given live feeds in order to wean to a dry diet more quickly while optimizing growth and survival.