Community Structure of Stream Fishes in the Upper Brazos River

Kenneth G. Ostrand and Gene R. Wilde, Department of Range, Wildlife, and Fisheries Management, Texas Tech University, Lubbock, Texas 79409-2125

The Brazos River has been altered throughout its course by the construction of reservoirs. Such alterations have been implicated in reductions in distribution and abundance of several species of minnows in Great Plains streams. In the Brazos River, distribution and abundance of the speckled chub Macrhybopsis aestivalis, plains minnow Hybognathus placitus, smalleye shiner Notropis buccula, and the sharpnose shiner Notropis oxyrhynchus, have declined in recent years. We collected fish from 13 sites in the upper Brazos River during 1997. A total of 14 species of fish were collected, of which Red River pupfish Cyprinodon rubrofluviatilis comprised the largest proportion (37.9%), followed by plains minnow (25.2%), smalleye shiner (14.8%), sharpnose shiner (7.4%), and speckled chub (0.8%). Abundance of sharpnose shiner and smalleye shiner were positively correlated with turbidity (P < 0.05). Red River pupfish abundances were positively correlated (P < 0.05), and smalleye shiner abundances were negatively correlated with conductivity (i.e., salinity) (P < 0.05). Conductivity decreased and turbidity increased with stream order (P < 0.05). Fish species diversity differed among 4th (D₂ = 0.53), 5th (D₂ = 0.83), and 6th (D₂ = 0.75) stream orders (P < 0.001). Patterns in the structure of stream fish assemblages in the upper Brazos River indicate that conductivity and turbidity are important abiotic variables.

Copyright © 1999
Texas Chapter of the American Fisheries Society
Last modified: 03/03/04 04:15:38 PM