Movement and Fate of Stocked Rainbow Trout in an Alabama Tailwater

Abstract

Hypolimnetic discharge from reservoirs in the southern U.S. provides water temperatures cold enough to support Rainbow Trout Oncorhynchus mykiss fisheries in regions where they otherwise could not exist. The Sipsey Fork tailwater in Alabama provides such an opportunity and is stocked with Rainbow Trout monthly. In a recent creel survey, less than 25% of the Rainbow Trout stocked each month were harvested and few trout appeared to persist in the system more than 3-4 weeks. The objective of this study was to describe post-stocking dispersal and fate of the non-harvested Rainbow Trout. In March, June, and October 2017, and January 2018, cohorts of Rainbow Trout were radio tagged and tracked to document movement patterns and to determine longevity in the fishery. Tagged Rainbow Trout from all cohorts dispersed an average of 4.1 km (SE = 0.3075 km). Only 30% of tagged Rainbow Trout remained alive 5-weeks post-stocking. The extent of predation on Rainbow Trout was assessed using a bioenergetics approach. Electrofishing surveys and diet analysis of predators identified Striped Bass as the primary predators of Rainbow Trout in the Sipsey Fork. Bioenergetics simulations revealed that approximately 500 Striped Bass living continuously in the tailwater from March through October could consume all Rainbow Trout stocked each month. Knowledge regarding the dispersal and fate of stocked Rainbow Trout in this system can improve management of the fishery.