Distribution, Status, and Land Use Characteristics of Subwatersheds within the Native Range of Brook Trout in the Eastern United States

Abstract

We examined and summarized existing knowledge regarding the distribution and status of selfsustaining populations of brook trout Salvelinus fontinalis at the subwatershed scale (mean subwatershed area ¼ 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.

Siblingship tests connect two seemingly independent farmed Atlantic salmon escape events

“…In the present study, we implemented siblingship tests for the first time, which led to an increase in the accuracy and confidence of assignment of the salmon escapees back to their farm(s) of origin. The identification of the relationships among siblings, either those that share 1 (half sibling) or both (full sibling) parents, has formerly been utilised to address a wide variety of questions in biology and ecology, such as elucidating fine-scale patterns of larval dispersal for a rocky reef fish on the open coast (Schunter et al 2014), determining individual variability in reproductive success (Hudy et al 2008, Liu & Ely 2009 and dispersal (Hudy et al 2008), providing some insight into the mating systems by inferring genotypes of unknown parents (Wang 2004, Kanno et al 2011) and tracing market product to the farm of origin in the event of detection of disease or toxins in the market fish (Hayes et al 2005).…”

Annual Changes in Seasonal River Water Temperatures in the Eastern and Western United States

“…The study area in the eastern U.S. included the native range of the eastern brook trout Salvelinus fontinalis as defined by the Eastern Brook Trout Joint Venture [19]. See DeWeber and Wagner [20] for the details.…”

“…See DeWeber and Wagner [20] for the details. This region was selected because the eastern brook trout is a cold water species of concern throughout much of its native range and one that has received considerable research and management attention within the context of the potential effects of climate change on suitable thermal habitat [19,21]. The UCRB was selected because it differs in climate, physiography and land use compared to the eastern U.S., and therefore, changes in the drivers of thermal habitat, such as climate change, may differ in these two regions.…”

Genetic Characteristics of Southern and Northern Brook Trout (Salvelinus fontinalis) Populations at the Zone of Contact

“…This species was once abundant in coldwater lakes and streams throughout its range, but environmental disturbances such as deforestation, development, and pollution: and the introduction of non-native rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta) have drastically reduced the number and sizes of wild populations [2].…”