Post-Stocking Recovery of Hatchery-Reared Trout: Dispersal Direction, Species and Behavioral Influences

Hatchery-reared trout are commonly released into streams throughout the United States, primarily for the purpose of increasing recreational angling opportunities.  The loss of hatchery-reared trout from the areas where they were initially released is a concern for cold-water fisheries managers.  In order to increase our understanding of the post-stocking loss of hatchery-reared trout and improve current management of cold-water fisheries, we examined the survival rates, dispersal, and behavioral characteristics of recently stocked salmonids.  The number of trout recaptured following release was low, with the majority of loss occurring within the first two weeks of release.  However, recapture rates increased over time for individuals that remained within the study areas for the two week period after initial release.  No interspecific differences in survival or recapture rates were observed among brook, brown, and rainbow trout.  Movements of trout ranged from 0.62 km to 29.77 km from the point of initial release and were predominantly in the downstream direction.  During behavioral observations, trout that had remained within the area of initial release initiated more aggressive encounters and were more active than trout that had dispersed to sites beyond the area of release.  Classification and regression tree analysis was successfully used to classify individual trout as either resident (individuals remaining within the study area for six weeks post-release) or non-resident (individuals moving outside of the study area following release) based on the observed behavioral characteristics of the fish.  Movement and loss of hatchery trout from stream reaches where they were planted continues to represent a significant challenge to fisheries managers