GROWTH-RESPONSES OF AGE-0 WHITE PERCH AND YELLOW PERCH FROM FIELD-ENCLOSURE EXPERIMENTS

In this paper, we investigate the potential for competition between ag e 0 white perch Morone americana and yellow perch Perca flavescens in field-enclosure experiments. In 1986 and 1987, different densities of white perch and yellow perch were stocked into cages in the western ba sin of Lake Erie and their growth responses determined. Fish were weig hed and measured pre- and post-stocking. In 1986 when fish were food-l imited, individual growth of both species were negatively affected by increased total fish density; yellow perch to a greater extent. In 198 7, experiments were carried out later in the year at lower temperature s. Yellow perch were shown to feed and continue to grow at lower water temperatures than white perch. We conclude that competition in summer may be mitigated in the fall because of differences in thermal optima between these two species.