Post-Stocking Performance of Catchable-Size Hatchery Rainbow Trout with and without Pectoral Fins

Abstract

We compared returns to the creel, survival, movements, and growth of several groups of hatchery rainbow trout (Salmo gairdneri), half with fully developed pectoral fins and half without pectoral fins. We stocked the fish at two locations on two different dates in Idaho's Portneuf River during 1979, and used angler interviews and electrofishing to assess their characteristics. There was no significant difference in total numbers of angler-caught trout with and without pectoral fins (632 vs. 630) or trout with and without pectoral fins (163 vs. 179) caught by electrofishing. There also was no significant difference in growth for 15 groups of trout measured at eight 2-week intervals throughout the summer after stocking. There was no significant difference in the movement of the two different groups of fish. Most (66% of total recovered) were recaptured within a few hundred meters of the stocking site. Only 17 trout (of 8,000 stocked in 1979) were reported caught in 1980, indicating poor over-winter survival and/or extensive movement from the study areas.