| Hatchery-reared trout are commonly released into streams throughout the United States, including Pennsylvania, mainly for the purpose of increasing recreational angling opportunities. The loss of hatchery-reared trout from the areas they were initially released has recently become a concern throughout Pennsylvania for cold-water fisheries managers. In order to increase our understanding of the post-stocking loss of hatchery-reared trout, and to improve current management of cold-water fisheries, we examined the survival rates, dispersal, behavior, and great blue heron predation of recently stocked salmonids. The number of trout recaptured after release was low, with the majority of the loss occurring within the first two weeks of release. No interspecific differences in survival and recapture rates were observed among brook, brown, and rainbow trout. Trout remaining within the area of initial release were consistently smaller, in terms of total length and mass, than those that had dispersed beyond the area of initial release. During behavior 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. The loss of hatchery reared trout appeared to be a combination of active dispersal and mortality due to predation. We suggest several possible changes in management plans to limit the post-stocking loss of hatchery-reared trout and associated negative ecological interactions with other fishes. |
