Effects of Unconventional Oil and Gas Development on Brook Trout Occupancy within an Actively Developing Watershed

Presentation: PowerPoint

Author(s): Eric R. Merriam Post-doctoral Research Assistant School of Natural Resources West Virginia University

Abstract: We conducted a large-scale assessment of unconventional oil and gas (UOG) development effects on brook trout distribution. We compiled 2231 collection records from the Upper Susquehanna River watershed, USA. We used boosted regression tree analysis to model occurrence probability at the 1:24,000 scale. Finally, we predicted occurrence within all un-sampled stream segments and quantified changes in occurrence attributed to UOG development. We predicted occupancy with a high degree of certainty (AUC>0.80). Agriculture was the dominant predictor of occurrence (~25% relative influence); however, UOG was retained in the final model (~2%). Approximately 45% of streams were predicted as occupied (probability >0.56), and 23% were identified as ‘high priority’ trout streams (>0.80). A total of 1214 streams were affected by UOG. Of those, UOG resulted in a loss of predicted occurrence in ~75 (6%) streams, 35 (3%) of which were ‘high priority’ trout streams. Streams wherein UOG resulted in a loss of predicted occupancy had intermediate levels of other stressors, suggesting the effects of UOG are most relevant in streams on the edge of the occupancy threshold due to pre-existing degradation.