WWW.WA S .ORG • WORLD AQUACULTURE • SEP TEMBER 2022 39 of cohort stocking and harvesting in freshwater ponds to provide suppliers and anglers with an alternative to reliance on seasonally available wild stocks. Acknowledgments This research was funded by Agricultural Research Service (586066-5-042), National Institute of Food and Agriculture (1006942) and Mississippi Agricultural and Forestry Experiment Station. Notes Brittany Chesser and Peter Allen Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Mississippi State, MS, USA. Corresponding author email: bmchesser@gmail.com References Burger, W., S.W. Ramee, C.M. Culpepper, III, C.C. Green and P.J. Allen. 2018. Demonstration of survival, growth, and reproduction of Gulf killifish Fundulus grandis in freshwater ponds. North American Journal of Aquaculture 80:88-96. Chesser, B.M. and P.J. Allen. 2020. Comparison of stocking time and density on Gulf killifish growth in freshwater ponds. Aquaculture Research 51:3452-3459. Ramee, S., C. Green and P.J. Allen. 2016. Effects of low salinities on osmoregulation, growth, and survival of juvenile Gulf killifish. North American Journal of Aquaculture 78:8-19. Tucker, C.S., and L.R. D’Abramo. 2008. Managing high pH in freshwater ponds. SRAC Publication No. 4604. juvenile fish, which are more vulnerable to high pH (Tucker and D’Abramo 2008). In the second study, density effects on growth rate and survival were evaluated. Juveniles, 7-9 weeks old, were stocked at 25,000 fish/ha or 50,000 fish/ha. Similar to the first study, densities were assigned randomly to three ponds and all ponds were evaluated for 12 weeks. Survival did not differ between densities and fish at both densities grew to over 7.5 cm in length on average. Although individual growth in length was lower in the higher density (Table 1), killifish at both densities reached market size in 29-31 days. Although density impacts growth rate, fish at both densities grew at rapid and steady rates. The rapid growth rates in these studies indicate ponds could be harvested earlier than the 12-wk timeframe. Growth was greatest during the first 40 days after stocking and market size was reached in 3-5 weeks. These results indicate multiple cohorts can be stocked throughout warmer months and grown to market size in one season at a stocking density of at least 50,000 fish/ha. Needed next steps include the development of an economic model to assess profitability of a two- or three-step culture process that includes use of intensive culture systems during earlier life stages and grow-out in freshwater ponds to market size. This rearing system would be beneficial for use of freshwater ponds throughout the seasonal growth period. Experiments are also needed to evaluate yet greater densities and increased frequency FIGURE 2.Gulf killifish at harvest. The rapid growth rates in these studies indicate ponds could be harvested earlier than the 12-wk timeframe. Growth was greatest during the first 40 days after stocking and market size was reached in 3-5 weeks. These results indicate multiple cohorts can be stocked throughout warmer months and grown to market size in one season at a stocking density of at least 50,000 fish/ha. TABLE 1. Effects of stocking time and density on growth and survival of Gulf killifish in freshwater ponds. Tr ea tmen t Mean g r owt h ( cm/wk) Mean sur v i va l (%) Year 1: Cohort 1 (June) 0.71 40 Year 1: Cohort 2 (July) 0.60 79 Year 2: 25,000 fish/ha 0.76 75 Year 2: 50,000 fish/ha 0.71 72
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