| Abstract: | Heretofore few quantitative studies on the tolerance of red drum (Sciaenops ocellata Linnaeus) to freshwater (FW) or dilute sea water have been conducted. In the laboratory we subjected larval and juvenile stages of red drum to dechlorinated FW for 96 hours and found 5% survival in larvae (23-day-old, 6.2 mm SL), 70% for postlarvae (34 and 47-day-old, 16.2 mm to 19.7 mm SL) and 95% for juveniles (57-day-old, 56.9 mm SL). Survival in control salinities of 10 ppt was 90% or greater. The results indicate that tolerance to dilute media is size dependent. In a separate experiment growth of juvenile red drum (52 mm SL) over a 30-day period was compared in two raceways with flow-through supplies of dechlorinated FW, and SW of ambient (35±2 ppt) salinity. SW fish grew significantly larger (P < .01) than those acclimated to FW. Within both treatments a large size differential developed with time. Food conversion efficiency was improved and appetite drive was enhanced in the SW treatment. Percent survival after 30 days was comparably high (93%) in both treatments. Fast growth and high survival of juvenile (>20 mm SL) red drum promote the feasibility of this valuable sport and commercial species in both FW and SW aquaculture. Its potential as a control fish in FW fishery management deserves further investigation. |
