The culture of estuarine fishes in net pens and cages in a power plant cooling system.
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A total of 11 species of estuarine fish were cultured in net pens and cages at different times from September 1, 1978 to June 30, 1979, at the Houston Lighting & Power Company's Cedar Bayou Generating Station near Baytown, Texas. Low salinity during the last 4 months of the period made it difficult to keep fish alive. An attempt was made to overwinter Florida pompano (Trachinotus carolinus). An infestation of Trichodina sp. in the gills of the fish caused over 90% mortality 3 weeks after stocking in November. The survivors died when the temperature dropped to 9 C in January. A comparison was made between net pens and cages for the culture of black drum (Pogonias cromis). Growth and food conversion efficiency of black drum was slightly better in net pens than in cages. The black drum in the cages were lost due to rough weather in December and January. Those in the net pens died in April when the salinity dropped to less than 1 ppt for more than 1 week. A vinyl coating containing tri-butyl tin oxide as a antifoulant was applied to the net pens and found to be effective in preventing fouling. No maintenance of the net pens was required in the 323 days they were immersed in water. An experiment was conducted to determine the optimum stocking density of Atlantic croaker (Micropogonias undulatus) in cages. Fish stocked at 5 kg/m3 had a greater growth rate and food conversion efficiency than those stocked at 10, 15, or 20 kg/m3. Production increased as stocking density increased. Highest production was achieved at a stocking density of 20 kg/m3. The increase in production was not proportional to the increase in stocking density. Guidelines to determine the optimum stocking density were established. Three feed types were compared for black drum culture in cages. Black drum fed a commercial diet containing 40% protein had a better growth and food conversion efficiency than those fed a diet containing 36% protein or ground fresh fish. Fish fed the 36% protein diet had a higher condition factor than those fed either of the other 2 diets. Other species used as biological monitors in the cooling system at various times during the study period were striped mullet (Mugil cephalus), pinfish (Lagodon rhomboides), Fundulus grandis, F. similis, Cyprinodon variegatus, blue catfish (Ictalurus furcatus) and redfish (Sciaenops ocellata).