Nasworthy Reservoir - 2006 Survey Report

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 33-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Nasworthy Reservoir were surveyed in 2006 using electrofishing and trap nets, and in 2007 using gill nets. Anglers were interviewed from September 2003 to August 2004 during a creel survey. This report summarizes the results of the surveys and contains a management plan for the reservoir based on those findings.

Reservoir Description

Nasworthy Reservoir is a 1,598-acre impoundment located on the southwestern edge of San Angelo, Texas in Tom Green County. It is a shallow, turbid reservoir with stable water levels and extensive emergent vegetation. Access is good with numerous public boat ramps and parks.

Management History

Important sport fish include largemouth bass, white crappie, and channel catfish. Palmetto (hybrid striped) bass have been stocked since the 1970s, and managed with an 18-inch minimum length limit. Red drum were once an important game species, but the discontinued operation of the power plant on Nasworthy Reservoir beginning in 2003 eliminated this fishery that was dependent on the plant’s heated water effluent.

Fish Community

• Prey species: Bluegill and gizzard shad were present in good numbers, but few gizzard shad were small enough to be available to predators. Few bluegills over 6 inches were present, and some anglers fished for and harvested this species.
• Catfishes: Blue catfish and flathead catfish were present in low numbers. Channel catfish were the most popular species for anglers at Nasworthy, and a high number were harvested. Channel catfish abundance and size structure were good.
• Temperate basses: White bass were present in low abundance, and were not targeted by many anglers. Palmetto bass (hybrid striped bass) were abundant, but very few fish over 18 inches were present. Few people fished specifically for palmetto bass in the creel survey.
• Largemouth bass: Largemouth bass abundance was good, but large fish were uncommon. Body condition was poor to fair, and growth was slow to moderate. This species was one of the most popular among anglers, especially anglers fishing from boats. About half of the legal-size bass caught by anglers were harvested.
• White crappie: White crappie were abundant; however, relatively few fish were legally harvestable (≥ 10 inches). All legal-size fish caught by anglers in the creel survey were harvested. White crappie were the fourth-most-popular species for anglers. Growth rates for crappie were moderate.

Management Strategies

• Investigate possible reasons for lack of large palmetto bass, skip 2008 stocking, and, if new information warrants continued stocking, request fingerlings at 4/acre every other year.
• Present alternative largemouth bass length limits to stakeholder groups and explore changing the regulation to improve size structure.
• Conduct management stocking of threadfin shad in spring 2008.
• Conduct standard electrofishing, trap netting, and gill netting in 2008-2009, and 2010-2011.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-30-R-32 Statewide Freshwater Fisheries Monitoring and Management Program