Genetic assignments for migratory bull trout captured in the Walla Walla and Umatilla rivers: assessing connectivity through genetic analyses

Bull trout (Salvelinus confluenus) spawn in cold, headwater streams and express a variety of life histories categorized by migration strategy. In the Columbia Basin, residents remain in their natal stream; fluvial and adfluvial bull trout, after rearing a year or two in their natal stream, migrate out to larger tributaries and lakes, respectively, for feeding and rearing then return to spawn in their natal stream. Migration is thus a critical component of bull trout life history and directly impacts their growth and reproductive success. Because of severe population declines, some related to migration impediments, bull trout were listed as threatened throughout the coterminous United States in 1999 (USFWS 2002). Studies are now underway to assess migration patterns, distribution, and abundance of bull trout as baseline information for recovery planning.