A Regional View of the Margin: Salmonid Abundance and Distribution in the Southern Appalachian Mountains of North Carolina and Virginia

Abstract

In the southern Appalachian Mountains, native brook trout Salvelinus fontinalis and introduced rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta are at the southern extremes of their distributions, an often overlooked kind of marginal habitat. At a regional scale composed of the states of Virginia and North Carolina, species were found to be distributed along latitudinal and elevational gradients. Native brook trout remain most common and abundant, decreasing both from north to south and from high to low elevations. Sympatry increases to the south, where rainbow and brown trout become more successful. For the region as a whole and within major drainages, allopatric and sympatric brook trout were generally found at higher elevations and rainbow and brown trout at lower elevations. Among drainages, elevations at which allopatric brook trout and rainbow trout are found generally increased to the south. A measure of effective elevation, which adjusts elevation for latitude, most clearly separated allopatric and sympatric brook trout from allopatric rainbow and brown trout.