Inks Reservoir - 2017 Survey Report

Prepared by Marcos J. De Jesus and Mukhtar Farooqi
Inland Fisheries Division
San Marcos District

This is the authors' summary from a 36-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Inks Reservoir were surveyed in 2017 using electrofishing and in 2018 using gill netting. Historical data are presented with the 2017-2018 data for comparison. This report summarizes the results of the surveys and contains a fisheries management plan for the reservoir based on those findings.

Reservoir Description

Inks Reservoir is a 768-acre impoundment of the Colorado River. It was constructed in 1938 by the Lower Colorado River Authority (LCRA) hydroelectric power, recreation, and water supply. The reservoir is located within the Llano uplift eco-region, and its shoreline length is 20.5 miles. Public access is only available through the state park. This stable-level rocky reservoir has plenty of structural fish habitat and some cover in the form of timber, emergent aquatic vegetation, and artificial fish attractors.

Management History

Sport fish include Largemouth Bass, sunfish species, Morone species, and catfish species. Recent management plans have recommended continuing monitoring populations under existing regulations. The Florida subspecies of Largemouth Bass was stocked in the reservoir in the late 1980s and early 1990s to increase Florida Largemouth Bass genetic influence in the population. Channel Catfish have been stocked by the Inks Dam National Fish Hatchery through an agreement with the LCRA or when surplus fish become available. Efforts to develop a trophy Sunshine Bass fishery were started in 2016. Recent efforts to mitigate the loss of fish habitat, due to reservoir aging, have included installing artificial and natural cover habitat, sunfish spawning gravel beds, and underwater green lights.

Fish Community

• Prey species: Gizzard Shad, Threadfin Shad, Bluegill, and Redbreast Sunfish were the predominant sources of forage. Shad abundance declined significantly, possibly due to immigrating predators during flood events.
• Catfishes: Channel and Blue Catfish were present in low-to-moderate abundance. Flathead Catfish were present in low abundance.
• Temperate basses: White Bass abundance remained low since the last survey. Striped Bass and Sunshine Bass have been historically present in low abundance. Immigration from Lake Buchanan during flood releases has been responsible for the Striped and Sunshine Bass population occurring in Inks Reservoir. Both species are stocked at Buchanan Reservoir. A major flood event in 2016 likely accounted for increased immigration from Buchanan Reservoir to establish at Inks. Anecdotal reports of high concentrations of moronid species followed the flood event.
• Black basses: Largemouth Bass were present in moderate to high numbers. Total catch rates and catch rates for fish ≥14 inches increased, respectively, since the previous survey. Largemouth Bass growth rate remained similar since the last survey. Presence of trophy-size individuals adds an appealing component to the fishery. Inks Reservoir also contained Guadalupe Bass.

Management Strategies

• Resume stocking Sunshine Bass fry at low densities, if needed in 2020.
• Stock Florida Largemouth Bass in 2019.
• Continue to refurbish aquatic fish habitat sites and promote the fishery.
• Inform the public about the negative impacts of aquatic invasive species.
• Conduct additional gill netting surveys in 2019 and 2020, and general monitoring surveys with gill nets and electrofishing in 2021-2022.
• Access and vegetation surveys will be conducted in 2021.

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