Calaveras Reservoir - 2019 Survey Report

Prepared by Randy Myers and Mitchell Nisbet
Inland Fisheries Division – San Antonio District

This is the authors' summary from a 34-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Calaveras Reservoir were surveyed in 2019 using electrofishing and in 2018 and 2020 using gill netting. Historical data are presented for comparison. This report summarizes the results of the 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, Hybrid Striped Bass, Blue Catfish, and Channel Catfish. Stockings of Red Drum and Hybrid Striped Bass have occurred most years since the mid-1970s and are required to maintain their populations. Advanced-size Sunshine Bass (4-6 inches), purchased by CPSE, were stocked in 2014-2017. Numerous other species were stocked historically, including marine fishes, to provide additional, unique angling opportunities. All sport fish are currently managed with statewide regulations, except Red Drum which have a 20-inch minimum length limit and no maximum length limit. Various Largemouth Bass harvest regulations have been used, and the current minimum length limit of 14 inches was implemented in 2015.

Fish Community

• Prey species: Gizzard Shad and Bluegill were the primary prey species in the reservoir. Threadfin Shad, Blue Tilapia, and Redear Sunfish are also important 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.
• Channel and Blue 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 2017, catfish angling comprised 20% of total angling effort, and catfish catch success (mean catch/h) was substantially lower in 2017 than in previous years.
• Hybrid Striped Bass: Relative abundance during the study period was very low and well below the historic average. In 2017, Hybrid Striped Bass angling comprised 2% of total angling effort with similar catch success as the previous survey conducted in 2010.
• Largemouth Bass: Relative abundance remained low and only a negligible fishery exists.
• 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 2017, Red Drum angling comprised 60% of total angling effort and Red Drum catch success was substantially higher than in previous surveys.

Management Strategies

• Continue the moratorium on stocking Hybrid Striped Bass until Shad spp. abundance increase to historic average level.
• Stock Channel Catfish and Blue Catfish fingerlings annually from 2020-2022.
• Continue annual stockings of Red Drum fingerlings at 200/acre.
• Conduct biennial gill net surveys to monitor populations of Red Drum, Channel Catfish, Blue Catfish, and Hybrid Striped Bass and creel survey sampling in either 2021 or 2022 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 2023.

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