Population and Survival Estimates of Catostomus latipinnis in Northern Grand Canyon, with Distribution and Abundance of Hybrids with Xyrauchen texanus
Douglas ME and Marsh PC. 1998. Population and Survival Estimates of Catostomus latipinnis in Northern Grand Canyon, with Distribution and Abundance of Hybrids with Xyrauchen texanus. Copeia. 1998(4):915-925
Population sizes, movements, and potential hybridization were examined for two indigenous Colorado River fishes, Catostomus latipinnis (flannelmouth sucker) and Xyrauchen texanus (razorback sucker) in the Little Colorado River (LCR) of Grand Canyon National Park and the Navajo Nation (Coconino County, AZ). Catostomus latipinnis is a "species of concern," and X. texanus is federally listed as endangered. Within Grand Canyon, both occur in greatest abundance in the LCR and its confluence with the mainstem Colorado River. During a 50-trip period (1 July 1991-27 June 1995), 2619 unique individuals (> 150 mm TL) were evaluated, consisting of 2578 C. latipinnis and 41 putative X. texanus/C. latipinnis hybrids. Cormack-Jolly-Seber estimates (adjusted for effort) were calculated by trip for C. latipinnis and ranged from 1591-5214 (average 2507). Seasonal estimates indicated peak movements in spring and autumn (especially the former). During 1991-1993, survival estimates of C. latipinnis were stable over all adult size classes (defined by overall body size) but decreased within larger size classes during 1994. Population estimates remained stable during the four years of the study. It is unknown whether C. latipinnis is at carrying capacity within Grand Canyon. A population estimate of putative X. texanus/C. latipinnis hybrids ranged from 8-136 (average 30) for 26 (of 48) trips. Xyrauchen texanus is a transitory member of Grand Canyon's indigenous fish community, moving through the canyon to more viable habitat up- or downriver. This aspect of its life history is now curtailed by Glen Canyon Dam, at the northern terminus of Grand Canyon.
- Type
- Journal Article
- Authors
- Douglas, Michael; Marsh, Paul
- Units
- GLCA , GRCA
- Keywords
- Animal Studies, AZ, Colorado River, Endemic Species, Fish, Flannelmouth Sucker (Catostomus latipinnis), Habitat Utilization, Little Colorado River, Migration, Population Dynamics, Razorback Sucker (Xyrauchen texanus), Threatened & Endangered Species