Amencan Fisheries Society 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 ele-vations 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. In the southern Appalachian Mountains, salmonids are at the southern margin of their dis-tributions in eastern North America. The original distribution of brook trout Salvelinus fontinalis, the only native salmonid, extended down the spine of the Appalachian Mountains through western Virginia and North Carolina and eastern Tennes-set to northeastern Georgia (MacCrimmon and Campbell 1969). Stockings have not notably ex-tended the distribution of brook trout in the southern Appalachians. Rainbow trout Oncorhyn-thus mykiss and brown trout Salmo trutta were introduced into the region in the late 19th and early 20th centuries. In this paper I will refer to the three species collectively as “trout.” In the Great Smoky Mountains of North Car-olina and Tennessee, introduced rainbow trout have generally been successful at lower elevations, and between the 1930s and the 1970s brook trout have been increasingly restricted to upper head