Technical Report

Habitat Use of Rio Grande Silvery Minnow

URL: https://webapps.usgs.gov/mrgescp/documents/Dudley%20and%20Platania_1997_Habitat%20Use%20of%20RGSM.pdf

Date: 1997/12/17

Author(s): Dudley R.K., Platania S.P.

Publication: Final report prepared for New Mexico Department of Game and Fish and U.S. Bureau of Reclamation, 88 p.

Abstract:

The primary purpose of this study was to characterize habitat use of Rio Grande silvery minnow at two sites, Rio Rancho and Socorro, in the Middle Rio Grande, NM. Habitat use was determined through a series of measurements of depth, velocity and substrate taken in the area where fish were collected. Habitat availability was measured along permanent transects at each site.

Rio Grande silvery minnow was relatively abundant at both sampling localities, but was more numerous and comprised a greater percentage of the total catch at Socorro than at Rio Rancho. Red shiner, western mosquitofish, flathead chub, fathead minnow, longnose dace and white sucker were present in moderate numbers at both sites, but the other 12 species collected during the study accounted for less than 5% of the total catch. Although the abundance of fish varied widely across time within sites, the majority of all fish were collected at the Socorro, NM site.

The mesohabitats most commonly occupied by all size-classes of Rio Grande fishes were low water velocity habitats over small substrata. Longnose dace occupied areas with greater water velocities and correspondingly larger substrata more frequently than did the rest of the ichthyofaunal community. Several other species (red shiner, flathead chub and channel catfish) also preferred higher velocity habitats but not to the degree exhibited by longnose dace. There was generally a higher degree of spatial separation between species at Socorro than at Rio Rancho. There was a moderate shift of fishes into lower water velocity habitats in the winter months.