Database
Lower Colorado River

Marsh & Associates, LLC (M&A) has assumed the role as a central repository of field data gathered by the Lower Colorado River Lake Mohave Native Fish Work Group (NFWG) since 2008, and prior thereto since creation of the Lower Colorado River Native Fish Database (database) at Arizona State University (ASU) in 1988. The NFWG formed in 1990 with representation from Arizona Game and Fish Department (AZGFD), ASU, U.S. Geological Survey, Nevada Department of Wildlife (NDOW), Bureau of Reclamation (Reclamation), U.S. Fish and Wildlife Service (USFWS), and National Park Service (NPS). The primary mission of the NFWG is to capture and rear native Colorado River fish for repatriation, in particular Razorback Sucker (Xyrauchen texanus). A functional wild population of Razorback Sucker no longer exists in Lake Mohave, but a population of repatriated fish does, and these fish spawn successfully every year. However, predation by non-native fishes precludes survival to the juvenile life stage so fish to support management must be harvested before they are decimated. 

The Lower Colorado River Native Fish Database (database) maintains native fish stocking and passive integrated transponder (PIT) tag data for the lower Colorado River (LCR). This includes lakes Mead, Mohave, and Havasu, and the river downstream from Parker Dam, which are defined as Reaches 1, 2, 3, and 4/5 of the Lower Colorado River Multi-Species Conservation Program (LCR MSCP). A primary purpose of the database is to support periodic estimation of population abundance of Razorback Sucker in Reach 2 on behalf of species conservation in the LCR basin, which is based upon adult monitoring data (excluding remote sensing). M&A handled data from 22,239 tagged fish during fiscal year 2024 for all reaches, including data on Razorback Sucker, Bonytail (Gila elegans), Flannelmouth Suckers (Catostomus latipinnis), and hybrids between the two sucker species.