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

Rio Grande Cutthroat trout Oncorhynchus clarkii virginalis (RGCT) represents the most southern subspecies of cutthroat trout, endemic to the Rio Grande, Canadian, and Pecos basins of New Mexico and southern Colorado. The subspecies currently occupies less than 12% of its historic range, and as such, the Mescalero Apache Tribe has partnered with the U.S. Geological Survey-New Mexico Cooperative Fish and Wildlife Research Unit, New Mexico State University, U.S. Fish and Wildlife Service, and the New Mexico Department of Game and Fish to meet mutually shared goals of restoring and maintaining a Pecos strain of RGCT on tribal lands. The goal of this project was to assess the suitability of the Rio Ruidoso within the Mescalero Reservation to support a self-sustaining RGCT population by conducting a systematic and comprehensive survey to characterize water quality, physical habitat (stream size, channel gradient, channel substrate, habitat complexity, riparian vegetation cover and structure, migration barriers), macroinvertebrate assemblages, and fish communities. Seven-100 m reaches throughout three major tributaries of the Rio Ruidoso within the Tribal lands were sampled during baseflow conditions October 2010, May 2011, and June 2012. Despite the onset of severe drought of 2011, water quality, physical habitat, and fish populations revealed that the Rio Ruidoso and its three tributaries would most likely support a self-sustaining RGCT population. Pools were abundant (mean, 8.9 pools/100 m), large amount of instream woody debris was present (range, 3.8-45.6 pieces/100 m), and instream dataloggers revealed daily maximum stream temperatures rarely exceeded the water quality criteria for coldwater fishes, however, the presence of frazil and anchor ice may limit fish distribution in the winter. Aquatic macroinvertebrate samples revealed a community of benthic invertebrates reflective of high quality cool to cold water. Overall densities of brown trout, rainbow trout and brook trout were high (overall mean, 0.23 fish/m2) and were in good condition (mean relative weight range, 84.51-117.89). Should the Mescalero Apache Tribe decide to introduce RGCT, we recommend a barrier be placed below the confluence of Middle and South Fork of the Rio Ruidoso. This would protect against invasion of non-native fishes and create approximately 12 km of perennial flow. We recommend the North Fork of the Rio Ruidoso not be considered for reintroduction due to easy access for the public to reintroduce non-natives into the watershed. Lastly, we recommend implementation of a long term monitoring program of RGCT to ensure no subsequent incursion of non-native fishes.