Choke Canyon Reservoir - 2017 Survey Report

Prepared by Greg Binion and Dusty McDonald
Inland Fisheries Division – Corpus Christi District

This is the authors' summary from a 40-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations were surveyed in 2017 using electrofishing and in 2018 using gill netting to assess population trends for important sport fishes. Anglers were surveyed from 1 January 2018 to 30 June 2018. Historical data are presented with the 2017-2018 data for comparison. This report summarizes the survey results and contains a management plan for the reservoir based on those findings.

Reservoir Description

Choke Canyon is a 25,989-acre reservoir (averaged 13,056 acres in 2017-2018) located on the Frio River in the Nueces River Basin, approximately 80 miles south of San Antonio. Its main purposes are water supply and recreation. The reservoir has a history of substantial water level fluctuations. The substrate is composed primarily of silt, sand, clay, and some gravel/rock. Littoral habitat consisted of native aquatic vegetation, periodically flooded terrestrial vegetation, standing timber, and seasonally abundant water hyacinth and hydrilla.

Management History

Important sport fish species include Largemouth Bass, Blue and Channel catfishes, White Bass, and crappie. Recent management efforts have focused on control of nuisance aquatic vegetation, compiling catch and harvest statistics on important sport fish species, documenting catch of trophy Largemouth Bass, and supplementing the Largemouth Bass population with stockings. The district has worked with the City of Corpus Christi to develop and implement a water hyacinth control program. District staff conducted herbicide treatments of water hyacinth from 2008 through 2015 totaling 926 acres. Since 2016, water hyacinth herbicide applications have been conducted through private contractors including treatments in 2016 (132 acres), 2017 (566 acres), and 2018 (104 acres). Staff annually monitored access areas where invasive vegetation could restrict use. Angler harvest of all sport fishes has been regulated according to statewide size and bag limits.

Fish Community

• Prey species: Gizzard and Threadfin Shad were present in the reservoir in low abundance. Sunfishes formed the primary forage base. Electrofishing catch of Bluegill was high and consistent with prior surveys. Several Bluegill greater than 6-inches were collected. The majority of prey species were adequate size for predator fish.
• Alligator Gar: The reservoir continues to support a robust Alligator Gar population. Anglers harvested an estimated 98 Alligator Gar through the first 6 months of 2018. A new waterbody record was caught in 2017 (8-feet, 216 pounds).
• Catfishes: Blue Catfish abundance remained high and size structure comprised a wide size range of fish. Angler success for Blue Catfish was high and anglers harvested an estimated 40,156 fish. Channel and Flathead Catfish were present in low abundance.
• White Bass: Abundance of White Bass was low throughout the survey period; however, all fish collected in 2018 were > 10 inches and thus available for angler harvest. Anglers harvested an estimated 3,101 fish in 2018 and angling catch rate decreased to 0.54/fish per hour.
• Largemouth Bass: Largemouth Bass abundance was high and size structure was balanced. Growth was excellent and mean age at legal length was 1.7 years. Largemouth Bass were the most sought sport fish species in the reservoir.
• White Crappie: White Crappie was the 4th most sought sport fish in the reservoir and was an important component to the overall sport fishery, especially for harvest oriented anglers.

Management Strategies

• Continue to manage sport fish populations under existing harvest regulations.
• Continue to assist the City of Corpus Christi with the water hyacinth control program.
• Monitor access areas with annual nuisance vegetation surveys where water hyacinth and hydrilla could restrict use.
• Stock Florida Largemouth Bass to maintain high level of trophy production potential and continue to collect data for Largemouth Bass trophy database.
• Develop an Alligator Gar monitoring program to track population and fishery trends.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-221-M-3 Inland Fisheries Division Monitoring and Management Program