Calaveras Reservoir - 2023 Survey Report

Prepared by Fernando Carvallo and Mitchell Nisbet
Inland Fisheries Division – San Antonio District

This is the authors' summary from a 32-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Calaveras Reservoir were surveyed in 2023 using electrofishing and in 2024 using gill netting. Historical data are presented for comparison. This report summarizes the results of recent surveys and contains a management plan for the reservoir based on those findings.

Reservoir Description

Calaveras is a 3,110-acre reservoir located on the southeast side of San Antonio in Bexar County, Texas. It was built in 1969 by City Public Service Energy (CPSE) for power plant cooling, and later opened for recreation. Recreation access is controlled by Thousand Trails Management Services, Inc., and paid entry is required. Water level is maintained at or near conservation pool by pumping from the San Antonio River. Aquatic plant coverage in the reservoir is minimal and primarily bulrush.

Management History

Important sport fishes include Red Drum, Blue Catfish, and Channel Catfish. Calaveras has been stocked regularly with Red Drum and Hybrid Striped Bass since the 1970s to maintain populations, however Hybrid Striped Bass stocking was discontinued in 2017 due to low stocking success and low forage abundance. Red Drum continue to be stocked annually. All sport fish are currently managed with statewide regulations, except Red Drum and Blue and Channel Catfish. Red Drum have a 3 fish daily bag limit and 20-inch minimum length limit and no maximum length limit. Blue and Channel Catfish regulations were amended to an aggregate daily bag limit of 15 fish and a minimum length limit of 14 inches in 2021.

Fish Community

• Prey species: Gizzard Shad and Bluegill were the primary prey species in the reservoir and Threadfin Shad, Blue Tilapia, and Redear Sunfish are also available as prey species. Combined relative abundance of prey species in the reservoir was slightly greater in the most recent survey compared to the previous survey and remains sufficient to support existing predator species populations.
• Catfishes: Relative abundance slightly increased during the study period for Channel Catfish and while higher than the previous study period, was lower than the historical average. Relative abundance has continued to decline for Blue Catfish and was lower than the historical average. In 2021 catfish angling comprised 9% of total angling effort, and angler success slightly was improved from 2017 but still lower than in previous years.
• Hybrid Striped Bass: Hybrid Striped Bass were not detected in the 2024 gill net survey. In 2021, Hybrid Striped Bass angling comprised 0.7% of total angling effort with few fish available for anglers due to the discontinuation of stocking.
• Largemouth Bass: No Largemouth Bass were sampled in our surveys and no anglers reported catches. A negligible fishery likely exists with low relative abundance.
• Red Drum: Red Drum were the most sought-after sport fish in the reservoir. Their relative abundance during the study period was increased and was higher than the historical average. In 2021, Red Drum angling comprised 72% of total angling effort and Red Drum catch success was substantially higher than in previous surveys.

Management Strategies

• Stock Channel Catfish or Blue Catfish fingerlings annually from 2024-2027.
• Continue annual stockings of Red Drum fingerlings at 200 fish/acre but discontinue Hybrid Striped Bass stocking until shad species increase back to historic levels.
• Conduct biennial gill net surveys to monitor populations of Red Drum, Channel Catfish, Blue Catfish, and Hybrid Striped Bass and creel survey sampling in 2026 to quantify the sport fishery and evaluate stocking effectiveness.
• Inform the public about the negative impacts of aquatic invasive species and conduct a vegetation survey in 2026.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-221-M-6 Inland Fisheries Division Monitoring and Management Program