World Aquaculture Magazine - September 2021

WWW.WA S .ORG • WORLD AQUACULTURE • SEP TEMBER 2021 35 Eggs were stocked at varying densities relative to the quantity spawned. Experimental trials and individual cohort performances informed researchers as to what culture protocols yielded the highest survival. Hatch occurred ~24 h after fertilization. The larval rearing tanks received water exchanges from 0-2 days post-hatch (DPH) and only overnight water exchanges after feeding began (Fig. 9) to maximize live food feeding efficiency and to remove uneaten feed and wastes. Salinity was maintained between 33-36 g/L and temperature was controlled with a chiller to stay between 19-23 C. Tisochrysis lutea algae (~150,000 cells/mL) was added to each larval tank daily from 1 to 25 DPH to provide shade and nutrient enrichment for live food organisms. Larval tanks were siphoned daily and the standpipe screen was cleaned as needed. Enriched rotifers were fed to each tank twice daily to maintain a density >10/mL. Rotifers were enriched with N-Rich Pro Plus (Reed Mariculture). Copepod ( Parvocalanus crassirostris ) nauplii were fed at a density of 8/mL twice daily. Experiments with larvae to 15 DPH (Fig. 10) revealed better survival with increasing percentage of copepod nauplii versus rotifers fed, increased algal density, and increased duration of copepods being fed. Individual tank survival to 15 DPHwas as high as 30 percent during experiments and batch effects were observed throughout the spawning season. Dry diet (Otohime B1) was fed starting at 8 DPH. Dry diet was fed from 8 to 100 DPH, increasing in particle size fromB1 to B2 to C1 to C2. Dry diet was offered up to eleven times daily and was accepted more readily by hogfish after metamorphosis (Fig. 11). A constant, slowwater exchange was started 11 DPH. Artemia nauplii were fed 12 to 45 DPH, when the larvae underwent metamorphosis. Artemia weaning began at 35 DPH and allowed for transition to another larger tank (Fig. 12). Thousands of F1 juveniles (Fig. 13) were produced in 2021 in anticipation of further grow-out research being conducted through 2021 and beyond. Future Considerations Optimistic results from egg incubation trials, grow-out trials, and continued spawning indicate that hogfish culture is feasible on a large commercial scale. The UF-IRECC-AL continues to have daily spawns with a production of 5.8 million fertilized eggs produced in 11 months (Fig. 7). Thousands of fish from early spawns are being used for ongoing research to define optimal larval and juvenile grow- out methods. Further research is planned for grow-out to market size, harem formation, and optimized broodstock harem formation. The critical information obtained from the first aquaculture research on hogfish shows great aquaculture potential as a possible foodfish candidate and for species conservation. ( C O N T I N U E D O N P A G E 3 6 ) FIGURE 8. Hogfish embryos. FIGURE 9. First-feeding hogfish larvae. FIGURE 10. Larval hogfish at 15 DPH. FIGURE 11. Juvenile hogfish at 28 DPH after having undergone metamorphosis.