The influence of submerged pulpwood on feeding and condition of fishes in a reservoir

Abstract

One hundred and forty years of log driving in the Kennebec River, Maine, left an estimated one to two million cords of submerged pulpwood logs, with major accumulations in reservoirs such as Wyman lake. Commercial salvaging of these logs began in 1978, which prompted a study to assess the importance of these logs to fishes and the potential effects of log salvaging. Vertical gill nets were set in Wyman Lake, in areas with and without logs, to measure fish densities and to obtain specimens for analysis of food habits and body conditions. Yellow perch (Perca flavescens) were more abundant in sites without logs (P < .05), but suckers (Catostomus spp.) were more abundant in sites with logs (P < 0.05). Yellow perch preyed primarily on cladocerans in sites without logs and on larger invertebrates in sites with logs, implying a difference in prey availability between study sites. Although the yellow perch and common shiners captured in non-log areas were longer than those in log areas (P < 0.05), their body conditions were not significantly different. Moderate log salvage operations would probably have little effect on the body conditions and abundances of fishes in Wyman Lake, if precautions were taken to avoid disruption of spawning and nursery areas at critical times of the year; impacts would vary in other lakes with differing topography and species compositions.