Use of Thermal Gradient Tanks in the Determination of Temperature Preferenda of Selected Estuarine Fishes

Abstract

The preferred temperature of juvenile Brevoortia patronus, Micropogon undulatus and Mugil cephalus and adult Menidia beryllina was determined in a 9.75m horizontal gradient tank. Juvenile fishes were used for all species except Menidia, and were acclimated to 20C. Individual fish were placed in a gradient tank with a 20 degree range and allowed to select a preferred temperature. Preferred temperature was found to be 20-25C for Micropogon undulatus, 21-30C for Mugil cephalus, 17-27C for Brevoortia patronus, and 21-29C for Menidia beryllina. The data collected indicates that many estuarine fishes may adapt efficiently to a wide temperature range. The comparison of field distribution data to experimentally determined temperature preference data shows a good correlation. However, significant field abundance of these fishes at temperatures below those found to be preferred indicates factors other than temperature influence fish distribution.