The Effect of Competition with Yellow Perch on the Survival and Growth of Planted Brook Trout, Splake, and Rainbow Trout in a Small Ontario Lake

Abstract

Abstract Matched plantings of hatchery-reared yearling brook trout (Salvelinus fontinalis) and splake (Salvelinus namaycush × S. fontinalis) or brook trout and rainbow trout (Salmo gairdneri) were made in Little Minnow Lake for 6 yr prior to and 6 yr following the introduction of yellow perch (Perca flavescens). The mean return for each kilogram of fish planted was 3.3, 6.8, and 6.1 kg, respectively, for brook trout, splake, and rainbow trout in pre-perch years but after yellow perch became established the mean returns were 0.4, 0.9, and 0.8 kg, respectively, all less than the weight planted. The 1967, 1969, and 1972 year classes of yellow perch successively dominated the fish community and yellow perch biomass fluctuated between 20 and 30 kg/hectare. The establishment of yellow perch resulted in a drastic change in the food habits of the planted salmonids and a reduction in their growth rates in excess of 50%. The evidence strongly indicates that planted salmonids could not compete successfully with yell...