Overwinter Mortality of Trout in Temple Fork of the Logan River

by Cerven, Daniel Richard

The objectives of this study were to determine the mortality rates of trout in Temple Fork of the Logan River during the winter of 1970-1971 and to identify factors related to trout mortality. Trout in seven 100-m sections of the 7 3-km stream were sampled by electroshocking in October, December, February, and April. Captured trout were weighed measured and tagged or fin-clipped. Scale samples were taken for age determinations and the fish were returned to the creek. Water temperature, snow cover, and anchor ice were monitored. Three species of trout were found in Temple Fork: brown, rainbow, and cutthroat trout. Daily instantaneous mortality rates were calculated for both marked trout and estimated numbers in the stream.