Lake Balmorhea - 2005 Survey Report

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Prepared by Mandy K. Scott and C. Craig Bonds
Inland Fisheries Division
District 1-C, San Angelo, Texas

This is the authors' summary from a 20-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Balmorhea Reservoir were surveyed in 2005 using electrofishing and trap nets, and in 2006 using gill nets and non-standard electrofishing. This report summarizes the results of the surveys and contains a management plan for the reservoir based on those findings.

Reservoir Description

Balmorhea Reservoir is a 573-acre impoundment located in the Pecos River Basin approximately 5 miles southwest of Balmorhea. Due to heavy irrigation demand, the reservoir water level usually drops severely each summer, reaching a low point in the fall, and then refills from spring inflows during the winter. However, water levels fluctuated less during 2004-2005 due to above-average rainfall. Balmorhea Reservoir experienced a mild golden alga (Prymnesium parvum) bloom and subsequent fish kill in winter 2004. A more severe bloom and fish kill occurred in winter 2006. Habitat was mostly nondescript shoreline or flooded dead terrestrial vegetation, with a small amount of native emergent vegetation.

Management History

Important sport fish include largemouth bass, redear sunfish, white crappie, and catfish. The fish populations were mostly eradicated in August 1998 in an effort to eliminate the introduced sheepshead minnow and improve the sportfish population that had been overtaken by carp, large shad, and small sportfish. TPWD re-stocked the reservoir with channel and blue catfish, Northern largemouth bass, sunfish, and white crappie during 1998-2001. A special research project included the introduction of triploid Florida largemouth bass from 1999 through 2003. Genetic analyses demonstrated that some cross-breeding was occurring between Northern and Florida largemouth bass, indicating that not all of the stocked Florida largemouth bass were sterile. After the fish kill of 2004, TPWD restocked the reservoir with fingerling blue and channel catfish, bluegill, and Northern largemouth bass, and adult white crappie.

Fish Community

• Prey species: Gizzard shad abundance and availability to predators were good. Bluegill abundance was also good, with mostly small individuals. Large redear sunfish were present in good numbers in fall 2005. Additional daytime electrofishing showed that bluegill and redear sunfish abundance may have been negatively impacted by the winter 2006 golden alga bloom.
• Catfishes: The catfish populations appeared to be non-existent.
• Largemouth bass: Largemouth bass were moderately abundant in fall 2005, but size structure was only fair; it is likely that most of the bass were products of recent stockings. Body condition was good. Additional electrofishing indicated that largemouth bass abundance may have been negatively impacted by the winter 2006 golden alga bloom.
• White crappie: Abundance was extremely low despite recent stockings.

Management Strategies

• Conduct additional gill netting in 2008.
• Stock bluegill, blue catfish, channel catfish, largemouth bass, and white crappie in 2007 to improve those fisheries.
• Discuss with controlling authorities the issue of possible overharvest from the inlet canal, and conduct a public meeting if needed.
• Work with controlling authorities to apply for state boat ramp grant.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-30-R-31 Statewide Freshwater Fisheries Monitoring and Management Program