Cooperative Fish and Wildlife Research Units Program: Montana Fishery
Education, Research and Technical Assistance for Managing Our Natural Resources

Buffalo Bill Reservoir (BBR) and the North Fork Shoshone River are two of the most popular fisheries in the Cody Region. These waters are managed as wild trout fisheries consisting of Yellowstone Cutthroat Trout (YSC), Rainbow Trout (RBT), Rainbow X Cutthroat hybrids (RXC), and few Brown Trout (BNT). Lake Trout (LAT), illegally introduced Walleye (WAE) and few Yellow Perch are also present in BBR. White and Longnose suckers are the primary components of the non-game fishery. Adult Rainbow and Yellowstone cutthroat trout migrate into the North Fork Shoshone River drainage in March through May spawn in tributaries and return to the reservoir in late summer. Migrant spawners range from 12 to 20 inches in length and from 4 to 9 years in age. Many juvenile trout out-migrate the year they are hatched, but some remain in tributaries for up to two years. Juvenile trout remain in the reservoir until they reach maturity. Historically, a majority of anglers on BBR have targeted Oncorhynchus spp. (i.e., YSC, RBT, and RXC). The illegal introduction of WAE (discovered in 2008) has the potential to negatively affect the existing trout fishery. A graduate research study (Johnson et al. in progress) is currently underway to determine food web dynamics and per-capita consumption of Oncorhynchus spp. by LAT and WAE. While this study is not complete, preliminary analysis indicates Oncorhynchus spp. comprise a substantial component of WAE diet in BBR. Furthermore, WAE have naturally recruited to the reservoir annually and the predation impacts from WAE likely have not yet been fully realized. Spawning congregations of WAE have been identified by FMCY which may provide opportunities to suppress this population. The proposed graduate study would aim to complement the ongoing study to identify management actions that could ensure the long-term persistence of the BBR Oncorhynchus spp. fishery.