Feeding Trials with Hatchery-Produced Gulf of Mexico Sturgeon Larvae

Survival and growth in larval Gulf of Mexico sturgeon Acipenser oxyrinchus desotoi fed live and formulated diets were evaluated. Live foods consisted of brine shrimp Artemia sp. and California blackworms Lumbriculus variegatus. Formulated diets consisted of commercially produced pellets and two experimentally formulated sturgeon starter diets (SS). Feeds were first offered at 5 d posthatch, 2 d before initiation of exogenous feeding. Significant differences (P < 0.05) in larval survival and growth were observed among dietary treatment groups. First-feeding larvae readily accepted the live food, especially brine shrimp decapsulated cysts, and they exhibited high survival (>95%) and specific growth rate (12%; SGR, logarithmic growth per unit time). In contrast, commercially formulated feeds were poorly accepted at the onset of feeding, and their use resulted in nearly complete mortality (>99%) by 3 weeks. First-feeding larvae, however, displayed preference for an experimentally formulated sturgeon starter diet (SS 9501), but survival (21.5%) and SGR (5.5%) were low by 3 weeks. Diet-switching experiments revealed that survival and growth rate of first-feeding larvae increased if they were fed brine shrimp for 1 week (>95% survival; SGR = 10.4%) and then switched to SS 9501 (83.8% survival; SGR = 10.0%). Also, after approximately 4–5 weeks, fish were easily weaned from live food or SS 9501 to the semimoist BioDiet starter diet (>70% survival). After 3–4 weeks of feeding on BioDiet, juveniles were converted to a variety of other commercial diets with no deaths.