Assessing Effects of Stocked Trout on Nongame Fish Assemblages in Southern Appalachian Mountain Streams

Abstract

Fisheries managers are faced with the challenge of balancing the management of recreational fisheries with that of conserving native species and preserving ecological integrity. The negative effects that nonnative trout species exert on native trout are well documented and include alteration of competitive interactions, habitat use, and production. However, the effects that nonnative trout may exert on nongame fish assemblages are poorly understood. Our objectives were to quantify the effects of trout stocking on native nongame fish assemblages intensively on one newly stocked river, the North Toe River, North Carolina, and extensively on other southern Appalachian Mountain streams that are annually stocked with trout. In the intensive study, we adopted a before–after, control–impact (BACI) experimental design to detect short-term effects on the nongame fish assemblage and found no significant differences in fish density, species richness, species diversity, or fish microhabitat use associated with trout stocking. We observed differences in fish microhabitat use between years, however, which suggests there is a response to environmental changes, such as the flow regime, which influence available habitat. In the extensive study, we sampled paired stocked and unstocked stream reaches to detect long-term effects from trout stocking; however, we detected no differences in nongame fish density, species richness, species diversity, or population size structure between paired sites. Our results revealed high inherent system variation caused by natural and anthropogenic factors that appear to overwhelm any acute or chronic effect of stocked trout. Furthermore, hatchery-reared trout may be poor competitors in a natural setting and exert a minimal or undetectable impact on native fish assemblages in these streams. These findings provide quantitative results necessary to assist agencies in strategic planning and decision making associated with trout fisheries, stream management, and conservation of native fishes.

Received March 19, 2013; accepted June 11, 2013

ACKNOWLEDGMENTS

We thank Ben Wallace, Justin Dycus, Patrick Cooney, Scott Favrot, Brad Garner, Christen Brown, Michael Fisk, Josh Raabe, Stephen Poland, Kyle Rachels, and Jeremy Remmington for their assistance in the field. Comments from Doug Besler, Rob Dunn, Julie Harris, and Ken Pollock improved earlier versions of this manuscript. This project was funded with Sport Fish Restoration Funds through the NCWRC (Project F-68, Study 10). Jake Rash, Doug Besler, Mallory Martin, and Kent Nelson of the NCWRC administered funding and offered guidance and insight in this project. The North Carolina Cooperative Fish and Wildlife Research Unit is jointly supported by North Carolina State University, NCWRC, U.S. Geological Survey, U.S. Fish and Wildlife Service, and the Wildlife Management Institute. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.