J. B. Thomas Reservoir - 2011 Survey Report

Prepared by John Clayton and Charles Munger
Inland Fisheries Division
District 1-A, Canyon, Texas

This is the authors' summary from an 18-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in J.B. Thomas Reservoir were surveyed in 2011 using electrofishing. Trap net surveys in 2011 and gill net surveys in 2012 were not conducted due to continued dropping lake levels and inability to launch a survey boat. This report summarizes the results of the electrofishing survey and contains a management plan for the reservoir based on those findings.

Reservoir Description

J.B. Thomas Reservoir is a 7,820-acre impoundment (constructed in 1952) on the main stream of the Colorado River. The dam is located 16 miles southwest of Snyder and west of State Highway 208, in Scurry County, Texas. The reservoir is owned by the Colorado River Municipal Water District and provides water to three member cities. The reservoir has a drainage area of 3,950 square miles; however, it experiences frequent water level fluctuations. The reservoir has declined steadily from approximately 3,917 acres in 2005 to 473 acres in 2012 due to drought and municipal water pumping. Angler access is good as most of the shoreline is accessible; however, there is currently no usable boat ramp. At the time of sampling, habitat consisted primarily of sand/silt and rocky shore.

Management History

Important sport fish include largemouth bass, white crappie, and catfish. The sport fish populations have only been managed with statewide regulations.

Fish Community

• Prey species: Catch rates for gizzard shad in the reservoir have declined from 399.5 fish/hour in 2007 to 114.0 fish/h in 2011. Although the Index of Vulnerability has also declined from 98 to 80, most shad were still available as prey to predators. Electrofishing catch of bluegills declined from 52.0 fish/h in 2007 to 24.0 fish/h in 2011, but it was up from 14.0 fish/h in 2003. No bluegill over 5 inches in length were collected.
• Catfishes: Due to low lake levels, catfish populations were not surveyed in 2012.
• White bass: Due to low lake levels, white bass populations were not surveyed in 2012.
• Largemouth bass: Electrofishing catch rates for largemouth bass increased from 27.0 fish/h in 2007 to 63.0 fish/h in 2011. Body condition was good; however, low lake levels and loss of habitat may have limited reproduction as indicated by no juvenile fish being collected during the survey.
• White crappie: Catch rates from a special project conducted by Texas Parks and Wildlife’s Heart of the Hills Fisheries Science Center in September 2010 indicate that white crappie were very abundant, but few fish sampled were of legal size. Growth was poor and 90% of the fish were below legal size.

Management Strategies

Conduct general monitoring with trap nets, gill nets, and electrofishing in 2015-2016. If lake levels rise to adequate levels allowing a survey by boat, conduct additional surveys to evaluate the effects of drought and low water levels on fish populations.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-221-M-2 Statewide Freshwater Fisheries Monitoring and Management Program