Kirk Strawn

Depth distributi.on of tarpon (Megalops atlantica), pinfish (Lagodon rhomboides), Atlantic Croaker (Micropogon undulatus), black drum (Pogonias cromis), and striped mullet (Mugil cephalus) placed in cylindrical cages extending from the surface to the bottom of the thermal effluent of a steam-electric power plant was monitored daily using a depth locator. Temperature,conductivity, pH, dissolved oxygen, turbidity, and gas saturation levels were recorded immediately after recording the depth distribution data. Overall trends suggested that intraspecific interaction had an effect on fish...

Channel catfish (Ictalurus punctatus), were reared in 1.0 m' cages suspended in the intake canal of a cooling reservoir. Effects of density were tested by stocking cages in replicates of 4 at densities ranging from 500 to 900 fish in increments of 25 individuals. There was a significant increase in net production and variation in length and a signifi· cant decrease in feed efficiency, mean fish weight, and percentage of harvestable-size fish as stocking density increased. Survival was not affected by number of fish per cage.

Individual heat resistance times were determined in 180 min experiments during June 1974 through September 1975 for 8 species of crustaceans and 47 fishes taken directly from the intake canal of the P. H. Robinson Generating Station, Bacliff, Texas. Indi· vidual r,esistance times increased with an increase in capture temperature and with a decrease in test temperature. June-September is the most thermally critical period of the year for animals transported by the power plant from intake water and exposed to hot discharge effluent. During the rest of the year, nearly all organisms survived...

Blue crabs, Callinectes sapidus, stocked in cages at two different densities both with and without artificial habitats were compared for growth and survival in a power plant discharge canal and in a pond. Survival was higher for crabs in the pond but growth was significantly greater for those in the discharge canal. Artificial habitats increased survival of crabs cultured in the discharge canal but had no effect on those caged in the pond. In the laboratory no significant differences were found in weight, carapace width, or survival of crabs selected at random in regards to molting cycle...

Threadfin shad can be successfully maintained in aquaria for long periods on a diet of newly hatched brine shrimp. They quickly die at 5.0 and will survive the winter in a lake that does not go below 90C.