Movement of Yellow Perch (Perca flavescens) and White Sucker (Catostomus commersoni) in a Nearshore Great Lakes Habitat Subject to a Thermal Discharge

Abstract

The thermal discharge from the Nanticoke Generating Station caused both yellow perch (Perca flavescens) and white sucker (Catostomus commersoni) to increase sharpness of turns, decrease distance between turns, and to orient into the current generated by the discharge. Conversely, fish released in thermally unaffected habitats referenced movement to the shoreline, turned less sharply, and swam greater distances between turns. The tendency for localization of movement was increased for both species when in the influence of the discharge. Swimming speeds were less for fish encountering the discharge; however, these fish had to contend with currents generated by the effluent thus making comparisons anomalous. Exposure of fish to elevated temperatures was brief and ranged from a few excursions into thermally elevated areas to approximately 9 h. Fish transplanted from unaffected areas to the discharge area showed behavior similar to fish caught and released at the discharge site. Two fish tracked when cooling water was discharged at ambient temperature suggested that current had a role in causing the observed changes in behavior.