Response of Brook Trout Biomass to Strategic Wood Additions in the East Branch Nulhegan River Watershed, Vermont

Abstract

AbstractHistoric logging and log driving have severely degraded fish habitat in many northeastern United States rivers, including the East Branch Nulhegan River, Vermont. To improve the habitat of Brook Trout Salvelinus fontinalis, 43 large woody material structures were constructed using chain saws and grip hoists in the East Branch Nulhegan River and two of its tributaries. The purpose of this study was to assess the effects of these “strategic wood additions” on Brook Trout biomass. Nine pairs of control and treatment sites were electrofished annually for 2 years prior to wood additions and for 4 years afterward. Wood loading increased at treatment sites by 183 to 1,557 pieces/ha, resulting in total wood loadings at these sites ranging from 251 to 1,557 pieces/ha (18 to 66 pieces per 100 m). By the second year of posttreatment sampling, average Brook Trout biomass at treatment sites had approximately tripled. Mean Brook Trout biomass decreased at control sites the first year after wood was added but then rebounded to pretreatment levels, suggesting that added wood contributed to a net increase in Brook Trout abundance in the system and did not simply concentrate fish in favorable habitats. Fisheries managers can consider strategic wood additions as a potential tool for improving Brook Trout habitat and bolstering their populations in streams where the lack of large wood is the most important limiting factor.