Nasworthy Reservoir - 2018 Survey Report

Prepared by Lynn D. Wright
Inland Fisheries Division - San Angelo District

This is the autho'rs 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 2018 using electrofishing, trap netting and in 2019 using gill netting and tandem hoop netting. Anglers were surveyed from June 2018 through May 2019 with a creel survey. Historical data are presented with the 2018-2019 data for comparison. 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 1,380-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. Red Drum were once an important game species, but the discontinued operation of the power plant on Nasworthy Reservoir in 2003 eliminated this fishery that was dependent on the plant’s heated water effluent. Palmetto Bass (Striped Bass x White Bass hybrid) were stocked from 1974 to 2007. In 2018 Palmetto Bass stockings resumed at a higher stocking density in an attempt to restructure the Gizzard Shad population.

Fish Community

• Prey species: Threadfin Shad were present in the reservoir. Electrofishing catch of Gizzard Shad was adequate, however Gizzard Shad IOV was poor. Electrofishing catch of Bluegill was slightly lower than previous years with most from 2 to 6 inches long.
• Catfishes: The Channel Catfish population had good size structure with fish up to 26 inches observed during sampling. Channel Catfish was the most sought after species in Nasworthy Reservoir. Blue Catfish were present in the reservoir in low abundance.
• Temperate basses: White Bass were present in the reservoir in low abundance. Palmetto Bass were abundant due to high density stocking in spring 2018.
• Largemouth Bass: The Largemouth Bass population continued to be characterized by poor size structure and slow growth. Largemouth Bass below the slot limit tended to be in poor condition while bass above the slot were in good condition. Nearly 16% of all anglers at Nasworthy Reservoir fished for Largemouth Bass.
• White Crappie: White Crappie were abundant and continued to have slow growth and poor condition. Most crappie reached legal size in 3.4 years.

Management Strategies

• Stock Palmetto Bass fingerlings at 75 fish/acre in 2020 to restructure the Gizzard Shad population.
• Recommend dropping the 10-inch minimum length limit on crappie to allow harvest of smaller crappie.
• Continue to evaluate the special slot regulation on Largemouth Bass with annual fall electrofishing surveys in 2020 and 2022 and a creel survey in 2022-2023.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-221-M-5 Inland Fisheries Division Monitoring and Management Program