Seasonal Abundance and Distribution of Marine Fishes at A Hot-Water Discharge in Galveston-Bay, Texas

Abstract

Biological and hydrological data were collected once each month Jan 1968-Dec 1969 at 11 offshore (trawl) and 6 beach (seine) stations in the discharge area of the P.H.Robinson Generating Stn at Galveston Bay, Texas. During all but hot months, most fishes appeared attracted to the effluent. During hot weather, they generally avoided the uncooled effluent in the immediate discharge area. Water temp decreased rapidly with distance from the outfall. The heated water flowed at the bottom rather than top of the water column during 2 of the 24 collecting trips. A few Gulf menhaden (during 1 of the 2 temp inversions) and sea catfish were killed in the summer by heat. The lowest elevated temp a sp avoided was 30{degree}C by the Gulf menhaden. Most spp were abundant in water up to 33-35{degree}C. Sea catfish and Atlantic croaker did not strongly avoid the effluent until temp exceeded 37{degree} and sand seatrout and striped mullet were collected in 40{degree}C water. The observed detrimental effects on the fish fauna in the discharge area of the power plant operating at either the 900 or 1465 mw capacity were negligible and restricted to hot months. Beneficial and potentially beneficial aspects were indicated during most months. Most fishes would not avoid the immediate discharge area if June-Sept effluents were cooled a few degrees before reaching Galveston Bay. Fishes are best served by no cooling of effluent during the remainder of the yr.