Cold Shock Susceptibility of Blue Tilapia from the Susquehanna River, Pennsylvania

Abstract

Abstract A population of blue tilapia Oreochromis aureus, a native species of Africa and southern Asia, became established in the Susquehanna River, Pennsylvania, after escaping from the Brunner Island Aquaculture Facility. It appears that blue tilapias are able to survive low water temperatures during winter by congregating in thermal effluents. The objective of this study was to determine the susceptibility of the Susquehanna River population to cold shock, and the conditions necessary to eliminate these fish from the thermal effluent at Pennsylvania Power and Light's Brunner Island Steam Electric Station. Blue tilapias were acclimated to 20° and 15°C and then exposed to sublethal and lethal temperatures under three patterns of temperature reduction–rapid cold shock or one of two rates of gradual temperature decrease (1°C/h or 3°C/h) to lethal temperatures–each test lasting 96 h and involving 20 fish per test group. Among fish acclimated to 20°C and immediately exposed to test temperatures, none died at...