Gila River Basin Monitoring

Long-term monitoring at multiple spatial scales through time (i.e., temporal) provides important insight on distribution, abundance, and dynamics of stream fish communities. In 1994, a long-term monitoring program was initiated by Bureau of Reclamation (Reclamation) as a requirement imposed by Fish and Wildlife Service (FWS) to monitor fish populations in selected waters of the Gila River basin due to impacts of the Central Arizona Project (CAP) on federally listed fishes (FWS 1994, 2001, 2008).  FWS determined that the canal and its interconnected channels had potential to degrade fish habitat as the CAP provided a mechanism for dispersal of non-native fishes into surrounding aquatic systems.

The initial monitoring program objective was to provide baseline data on distribution and abundance of non-native fishes in the CAP canal system and its primary connected waters. In 2012, Reclamation and FWS in collaboration with Arizona Game and Fish Department (AZGFD) and New Mexico Department of Game and Fish (NMDGF) shifted focus further upstream of the CAP canal system to gather information on the status of wild populations of federally listed and candidate fishes.

Currently, the objective for the monitoring program is to identify presence and distribution of each target species in the streams being monitored. Secondarily, evaluate fish community structure to determine relative abundance of focal species within the community of co-occurring fishes. Moving forward, the program goal will be to better assess conservation status of federally listed focal species by calculating population size indices, determining fish assemblage structure including non-natives, documenting reproduction and recruitment, and determining geographic extent for each focal species (Mosher et al. 2020).