Semester

Fall

Date of Graduation

2025

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Division of Forestry and Natural Resources

Committee Chair

Kyle Hartman

Committee Member

Stuart Welsh

Committee Member

David Thorne

Abstract

Understanding the extent that anglers targeting stocked trout end up harvesting wild Brook Trout Salvelinus fontinalis addition to studying how non-native trout species affect native Brook Trout populations is important for effective management and conservation in the central Appalachian Mountains. This thesis addresses these concerns in two parts. The first chapter used a combination of creel surveys and non-lethal morphometric methods to estimate wild Brook Trout harvest rates on four stocked streams during the West Virginia spring stocking season. A generalized linear model was developed to determine the origin (wild vs. hatchery) of Brook Trout harvested by anglers. This differentiation model was based on three easily collected, non-lethal field metrics: caudal fin erosion (adapted from existing fin erosion scales), total fish length, and a slope value calculated from circuli spacing on scales. The model achieved 97% classification accuracy and a Cohen’s kappa of 0.93, indicating strong agreement with known-origin fish. Of 77 Brook Trout of unknown origin collected during creel surveys, the model predicted that 3.89–5.19% were of wild origin. Although this harvest rate is low compared to that of stocked fish, it may still represent a meaningful source of wild Brook Trout mortality in systems with high angler effort and low wild Brook Trout abundance. Angler-harvested fish predicted to be wild were only encountered in Gandy Creek and the South Branch Potomac River, while no wild Brook Trout were identified at Little River or the North Fork South Branch Potomac River. High stocking rates, angler preference for larger fish, and frequent catch-and-release of smaller trout likely contributed to the low wild harvest rates. Overall, harvest of wild Brook Trout by stocked trout anglers likely has less impact on populations than catch-and-release mortality (including culling) and anglers targeting wild Brook Trout outside the stocking season. The second chapter examined whether the presence of non-native trout, either stocked or naturalized, affects the abundance, size structure, and total biomass of Brook Trout in West Virginia streams. Streams in the native range of Brook Trout are frequently supplemented with hatchery-raised trout, and in many of these streams non-native trout species have become naturalized. Little is known about how these non-native species may influence Brook Trout populations. This study used long-term electrofishing data from 838 stream surveys across 117 different streams, collected by West Virginia University and the U.S. Forest Service from 2003 to 2024. Linear mixed effects models were used to test relationships between Brook Trout population metrics and non-native trout presence, with non-native trout presence and stream wetted width as predictor variables and stream name and year, and bedrock geology age as random effects. For each Brook Trout population metric none of the best fit models based on AIC were statistically significant. Although not statistically significant, the model predicted a slight increase in Brook Trout abundance when non-native trout were present. Similarly, Brook Trout biomass, average length, and young-of-year abundance showed no significant differences when non-native trout were present. These results suggest that the presence of non-native trout in the streams examined does not negatively impact wild Brook Trout populations. Greater stream productivity in systems with non-native trout and the abundance of smaller cold tributaries that favor Brook Trout may help mitigate negative competitive interactions.

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