The Atlantic Croaker Micropogonias undulatus (Sciaenidae) is a candidate species for marine baitfish aquaculture in the southeastern United States because of its high value and common use as live bait by recreational fishers. However, an efficient larviculture procedure has not been reported to date; development of such a procedure was the impetus for this study. Embryos were obtained from captive broodstock that were induced to spawn volitionally by using a single injection of a luteinizing hormone releasing hormone agonist. Larvae were cultured at low density (initial density = 6.4 larvae/L) via intensive culture methods, including the use of recirculating filtration systems and of rotifers, brine shrimp Artemia spp., and micropellets as larval foods. The trial was performed in six 1,100‐L tanks at a salinity of 14–29‰, with average rearing temperatures of 23.6°C and 24.6°C. At the completion of the study (39 d posthatch), mean SLs were 24.7 mm (SE = 0.738) for larvae cultured at 24.6°C and 23.0 mm (SE = 0.624) for larvae cultured at 23.6°C. Mean survival at 39 d posthatch was 25.9% and did not differ significantly between temperature groups. This work demonstrated a successful methodology for intensive larviculture of Atlantic Croakers and can serve as a platform for the experimentation that will be necessary to develop economically viable procedures for intensive production of this species.
Eggs of Acartia tonsa and Parvocalanus crassirostris were contaminated with ciliates (Euplotes sp.) and exposed to five concentrations of sodium hypochlorite (25, 55, 105, 205, and 405 mg/L) for durations of 15 s, 5 min, 15 min, or 30 min to assess the efficacy of household bleach for removing the ciliates. Eggs from each exposure treatment were incubated for 40 h (A. tonsa) or 12 h (P. crassirostris) to assess hatch. The presence of living ciliates was evaluated after incubation, and the egg hatch rate (%) for the copepods was estimated for each treatment and in controls. Exposure to 105 mg/L total chlorine for 15 s killed all of the ciliates and reduced the copepod hatch rate by less than 26% with respect to controls in both species. Exposure to 55 mg/L for 15 min or 25 mg/L for 30 min also killed the ciliates and achieved a mean copepod hatch rate of 38.5% and 58.1% of the control‐group hatch rate, respectively, in A. tonsa. Treatments for 5 min or longer reduced the hatch rate for P. crassirostris eggs by at least 76% at all of the concentrations that we tested.
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