Choke Canyon Reservoir - 2019 Survey Report

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

This is the authors' summary from a 44-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations were surveyed in 2019 using electrofishing and multifilament gill netting (Alligator Gar) and in 2020 using gill netting and low frequency electrofishing to assess population trends for important sport fishes. Anglers were surveyed from January through June 2020.  Historical data are presented with the 2019-2020 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 17,147 acres in 2019-2020) 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 gravel/rock.  Littoral habitat consisted of native aquatic vegetation, periodically flooded terrestrial vegetation, standing timber, hydrilla, and seasonally abundant water hyacinth.

Management History

Important sport fish species include Largemouth Bass, Blue and Channel Catfishes, White Bass, and crappie.  Alligator Gar are also an important component to the overall fishery. 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, supplementing the Largemouth Bass population with stockings, and developing an Alligator Gar monitoring program. 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 (926 total acres).  Since 2016, water hyacinth herbicide applications have been conducted through private contractors including treatments in 2016 (132 acres), 2017 (566 acres), 2018 (104 acres), and 2019 (5 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 Shad were present in high abundance and formed the primary forage base.  Bluegill and Redear Sunfish were present in low abundance.  The majority of prey species collected were adequate size for most predator fish.    
• Alligator Gar:  The reservoir continues to support a robust Alligator Gar population.  Anglers harvested an estimated 185 Alligator Gar through the first 6 months of 2020.  Several trophy-sized (≥ 6 ft) Alligator Gar were harvested by anglers.  A new waterbody record was established 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 52,384 fish.  Channel and Flathead Catfish were present in low abundance. 
• White Bass:  Abundance of White Bass was low throughout the survey period; half of the fish collected in 2020 were > 10 inches and thus available for angler harvest.  Angler harvest was high in 2020 and angling catch rate increased to 1.3/fish per hour. 
• Largemouth Bass:  Largemouth Bass abundance decreased from prior surveys and size structure was primarily comprised of smaller individuals.  Growth was excellent and mean age at legal length was 1.8 years.  Largemouth Bass were the most sought sport fish species in the reservoir; including both tournament and non-tournament anglers.
• Crappies:  Crappies remained an important component to the overall sport fishery, especially for harvest-oriented anglers.  Angling catch was 1.3/h and total harvest was 10,682 fish.

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 the Largemouth Bass trophy database. 
• Continue to refine the Alligator Gar monitoring program to track population trends and monitor harvest through the mandatory harvest reporting system.

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