Habitat Requirements, Vital Rates, and Movement Patterns of Three Endemic Fish in the San Rafael River, Utah

The native Colorado River Basin ichthyofauna represents one of the most imperiled fish assemblages in the world. Habitat alteration, water development, fragmentation, and interactions with non-native species have led to severe declines in both distribution and abundance of many endemic fishes. The bluehead sucker (Catostomus discobolus), flannelmouth sucker (Catostomus latipinnis) and roundtail chub (Gila robusta) are species native to the Colorado River Basin which have experienced severe declines in abundance and distribution and thus, placement on the Utah Sensitive Species List. However, all three species are found in the San Rafael River in southern Utah, providing an area of high conservation priority. Our goal is to estimate vital rates, migration patterns, and habitat requirements for each species and life stage, the critical components for completing robust population viability analyses and to evaluate management options. In 2007, we sampled fish from 22 systematically selected (random seed) 300-m stream reaches. All fish were weighed, measured, and released. Target species were PIT tagged. Habitat parameters were recorded in each sampled reach. Although non-native fish comprised the majority of our catch, 20 native fish were PIT tagged, including flannelmouth sucker and roundtail chub of multiple age classes, along with a pair of adult bluehead sucker. Age-0 flannelmouth sucker distribution showed a strong correlation with backwater habitat. Although successful reproduction was documented, recruitment was likely negligible as water development and drought led to the near-complete dewatering of the San Rafael River in the summer of 2007. Future research will include the installation of a solar-powered antennae and additional early-spring sampling. The data collected as part of this study will be used to develop a population viability model, including source and sink dynamics that will allow resource managers to plan future research, assess vulnerability, and rank management options for these sensitive species