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Mesohabitat Use and Community Structure of Brazos River Fishes in the Vicinity of the Proposed Allens Creek Reservoir

Frances P. Gelwick, Raymond Y. Li

This report was produced by TAMU graduate student Raymond Li, under the supervision of TAMU Wildlife and Fisheries Department researcher Fran Gelwick. This research was largely supported by the Texas Water Development Board and this report was transmitted to TWDB. Li was funded with a 2002 TWRI Mills Scholarship, which provided a $1,000 grant to assist in this project.

To accommodate projected increases in the demand for water, the Texas Water Development Board (TWDB) adopted the Texas Water Plan in 1997. The Texas Water Plan identifies Allens Creek as a potential reservoir site to supply water for the growing populations of Fort Bend and Brazoria counties and central Texas. Water from the lower Brazos River will be diverted to the proposed 142,982 acre-feet reservoir. This project was designed to provide information concerning Brazos River fish communities. To assist in modeling reduced instream flows 15th, 30th, and 50th percentile discharges of the summer and winter seasons were targeted for fish collections. Previous studies documenting fishes occurring near our study reach can be found in Linam et al. (1994) and Winemiller et al. (2000). Studies reporting fish communities of tidal portions and upper reaches of the Brazos River can be found in Johnson (1977), Wilde and Ostrand (1999), Winemiller and Gelwick (1999), and Ostrand and Wilde (2002). McEachran and Fechhelm (1998) lists documented species occurrences in the Brazos River watershed.

This report provides information on habitat characteristics and fish assemblages across 15th, 30th, and 50th percentile discharges in summer and winter. The objectives of this project were to: (1) delineate and photodocument riffle, run, and pool mesohabitats within our study reach; (2) characterize and quantify the fishes occurring in identified mesohabitats; (3) determine indicator species of mesohabitats based on fish distributions; and (4) calculate an Index of Biotic Integrity for the reach.

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