Evaluation of a Hidrostal Pump Fish Return System

Abstract

We tested the effectiveness of a Hidrostal pump and filtered mercury vapor light system for attracting, concentrating, and transporting fish commonly impinged on water intake structures of thermal electric generating stations on the Great Lakes. In general, the Hidrostal pump effectively transported test fish with relatively low mortality rates. Mortality varied among fish species, with rainbow trout (Salmo gairdneri) significantly hardier than yellow perch (Perca fiavescens) and alewife (Alosa pseudoharengus). Mortality also generally increased at higher pumping speeds, while mortality of yellow perch was greater in a long transport loop than in a short transport loop. In tests of fish attraction and capture, the addition of a filtered mercury vapor light significantly increased the efficiency of fish capture of the Hidrostal pump transport system. Other directive cues (bubble curtains, strobe lights, and electric fields) did not significantly improve the efficiency of the Hidrostal pump-mercury vapor light system. Capture efficiency varied significantly among fish species and increased with duration of the test period.