Effects of stocked trout on native nongame riverine fishes

Stocking waters with hatchery-reared trout species (Salmonidae) to support recreational fisheries is common practice; however, the effects on native nongame fish communities are poorly understood.  We conducted research during 2008-2009 on the North Toe River, North Carolina, a high gradient Appalachian Mountain river.  We employed a BACI (before-after-control-impact) experimental design with snorkeling surveys to intensively quantify density and microhabitat use of the fish community at a treatment reach and two downstream reference reaches before and after trout stocking.  We also extensively backpack electrofished other stocked trout waters across North Carolina paired with unstocked reference sites.  Our intensive study detected no significant changes in fish density, microhabitat use, or community composition as a result of stocking, but we observed differences between years at all sites.  This suggests the fish community responded to environmental conditions, but not differentially in the stocked site.  We also detected no differences in density, community composition, or average fish weight among paired electrofished sites.  Our results suggest minimal ecological effects of trout stocking on the nongame fish assemblage, relative to the inherently high variability in fish community dynamics.  These findings may assist agencies in planning for recreational fisheries and nongame fish conservation efforts in coldwater river ecosystems.