The Determination of the Population and Range of Brook Trout in a Pond
The following study was conducted on a man-made pond, the physical conditions of which were comparable to those of a beaver-made pond. Like a beaver-pond, the man-made pond was formed by the damming of a small stream and. allowing the pond to take the form of the stream valley. Like a beaver dam, the man-made dam allowed tor a continual flow of water through it. And like many beaver porns, the average depth of this pond was approximately four and one-half feet. That the physical conditions of the man-made pond were comparable to those of a beaver-made pond was indicated by the fact that this stream, which has remained essentially unchanged tor the last forty years, had previously been dammed by beaver and that during the course of this study two beaver took up residence on the pond. It is here suggested that the procedures used and the conclusions reached in this study of brook trout in a man-made pond may in every way be applied to a study of brook trout in a beaver-made pond. The first purpose at this study was to determine the number of brook trout in the pond and thereby have some measure of the pond's suitability as a habitat for brook trout. The second purpose of this study was to determine the range, that is, the forage area, of brook trout in a pond which, to my knowledge has never been ascertained. Gerking did conclude, however, in a lengthy survey of two Indian streams where fish were caught, marked, and re-caught, that four-fifths of the fish surveyed remained in the same pond. That is, four-fifths of the fish surveyed had a home range. Likewise, Hunt, in a survey of Lawrence Creek, Wisconsin, concluded that approximately four-fifths of the trout in that stream had a home range of three-quarters of a mile or 1ess.