Long-Term Trout Production Dynamics inValley Creek, Minnesota

Abstract

Abstract Long-term studies in Valley Creek, Minnesota, continued from April 1965 to April 1986. Initially, the brook trout Salvelinus fontinalis was the only trout species present, but both rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta later entered the study section. Brook trout declined after severe floods, recovered, declined again after an extreme sedimentation, and continued to decline while brown trout increased. Brook trout biomass, initially at 184 kg/ha, decreased to 4 kg/ha at the end of the period, a reduction of 98%. Rainbow trout entered the study section when floods overflowed private ponds, but their population did not reach high levels. After its entrance, the brown trout increased to predominate the trout fauna with a final biomass of 201 kg/ha. At the end of the study period, brook trout biomass remained at 2% of all trout species, rainbow trout at 5%, and brown trout at 93%. Maximum annual production by brook trout, near the beginning of the 21-year period, was 171 kg/h...