We conducted an electrofishing injury study to evaluate potential effects of sampling procedures on survival and health of hatchery rainbow trout Oncorhynchus mykiss (187-307 mm total length) stocked into an Ozark stream. We assessed two groups of trout: one group had acclimated to stream conditions for 1 month; the other group was handled and transported just before the study. Each group was sampled by electro-fishing (boat-mounted, 60-Hz AC) and seining (controls), resulting in four treatment groups (N = 21). We held fish for 48 h to evaluate mortalities in that period, then euthanized all fish and examined them for hemorrhages and spinal damage. No fish died during the 48-h holding period, indicating that our procedures did not cause significant sampling-related mortality among stocked trout in Brush Creek. Spinal damage was observed in 5% of fish collected with electrofishing but in none of the control fish. We found hemorrhages in 90% of electrofished trout but none in control fish, and recently handled and hauled trout had a greater occurrence and severity of hemorrhaging.
Additional publication details
Electrofishing injury and short-term mortality in hatchery-reared rainbow trout stocked into an Ozark stream