EFFECTS OF STOCKING DENSITY, SALINITY, AND LIGHT-INTENSITY ON GROWTH AND SURVIVAL OF SOUTHERN FLOUNDER PARALICHTHYS LETHOSTIGMA LARVAE

Four separate studies were done on Southern flounder Paralichthys leth ostigma larvae during first feeding and metamorphosis to determine the effects of stocking density, salinity, and light intensity on growth and survival, One study used stocking densities of 10, 20, 40, and 80 fish/L during first feeding; the second study compared the growth and survival of larvae stocked at 20 and 33 ppt; and a third experiment ev aluated stocking; densities of in and 3/L under two different light in tensities (1,600 lux vs 340 lux) during metamorphosis, The fourth expe riment tested the effects of different salinities (0, 10, 20 and 30 pp t) on larval growth and survival during metamorphosis, Growth and surv ival (overall 6.9%) were not significantly different (P > 0.05) for st ocking rates up to 80/L. Larvae placed into 20 ppt salinity had surviv al through first feeding similar to that of larvae raised at 33 ppt, D uring metamorphosis, light intensity had no effect (P > 0.05) on growt h or survival, but fish stocked at 3/L had significantly lower (P < 0. 05) survival than fish at 1/L, Complete mortality of larvae occurred a t 0 ppt, Growth and survival past metamorphosis were not significantly different (P > 0.05) at 10, 20 and 30 ppt, but unmetamorphosed fish d id not survive to day 60 at 10 ppt, Based on these results, practical larviculture of Southern Bounder may require a two-step process with h igh stocking rates (80 fish/L) through first feeding and lower densiti es (1/L) through metamorphosis. Fingerling production in fertilized nu rsery ponds might be possible at salinity as low as 20 ppt.