Medina Reservoir - 2016 Survey Report

Prepared by Randall Myers
Inland Fisheries Division
San Antonio District

This is the author's summary from a 27-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Medina Reservoir were surveyed using electrofishing in 2016 and gill netting in 2017. Historical data are presented with the 2016-2017 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

Medina Reservoir (5,410 acres) was constructed in 1913 and is located on the Medina River in Medina and Bandera counties, Texas. It was built for irrigation water supply. The reservoir experienced a considerable water level increase in 2015 filling to conservation pool elevation from 80 feet low. As a result, boat ramps re-opened. Most of the shoreline is characterized as rock bluff or rocks and gravel. Flooded terrestrial vegetation is currently the predominant fisheries habitat type.

Management History

Important sport fish include Largemouth Bass, Palmetto Bass, and White Bass. All species have been managed under statewide regulations. Florida Largemouth Bass fingerlings have been stocked infrequently and most recently in 2016 when fisheries habitat was optimal for survival. Palmetto Bass have been stocked on an irregular basis due to variable availability and water level fluctuations.

Fish Community

• Prey species: Gizzard Shad, Threadfin Shad, and sunfish spp., primarily Bluegill, comprise the prey community. Gizzard Shad abundance increased immediately after reservoir refill and then decreased. Bluegill abundance has continued to increase. These species were sufficiently abundant as a group, and sufficiently sized to support existing predators.
• Catfishes: Both Blue Catfish and Channel Catfish abundance has remained consistently low. Blue Catfish population size structure has improved, whereas Channel Catfish population size structure was poor.
• White Bass: Abundance was lower in 2017 than in 2011 when water level was lower by about 25 feet. The majority of fish collected in 2017 exceeded 10 inches total length (TL), and all sizes of fish exhibited good body condition.
• Palmetto Bass: Abundance was lower in 2017 than in 2011. Fish collected in 2017 ranged in size from 12 to 23 inches. Smaller individuals likely resulted from the most recent stocking which was conducted in 2016 following reservoir refill in 2015. The larger fish collected in 2017 were likely from stockings conducted in 2011, prior to the prolonged low-water level event.
• Largemouth Bass: Relative abundance increased tremendously following reservoir refill in 2015. Florida genotype fish represented a greater fraction of the population in 2016 (17%) than in 2012 (3%). The population is mostly comprised of sub-legal length fish. Growth was moderate and could have been negatively influenced by high fish density. Age-0 and age-1 fish averaged 5.5 and 11.0 inches TL, respectively, in 2016.

Management Strategies

• Maintain the Palmetto Bass fishery by annually stocking 5-15 fish/acre.
• Inform the public about the negative impacts of aquatic invasive species, and monitor for presence of aquatic invasive species during routine fish population and habitat surveys.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-221-M-2 Inland Fisheries Division Monitoring and Management Program