Granbury Reservoir - 2009 Survey Report

Prepared by Michael S. Baird and John Tibbs
Inland Fisheries Division
District 2-B, Waco, Texas

This is the authors' summary from a 29-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Granbury Reservoir were surveyed in 2009 with a boat electrofisher and in 2010 using gill nets. This report summarizes the results of the surveys and contains a management plan for the reservoir based on those findings.

Reservoir Description

Granbury Reservoir is an 8,700-acre impoundment located within the Brazos River system in Hood County, Texas. Near constant water level is maintained by a spillway consisting of 16 tainter gates and 2 sluice gates; retention time has been estimated at 260 days. Primary water uses include storage of flood and storm waters, municipal water supply, power plant cooling, and recreation. Granbury Reservoir has only moderate productivity yet the fishery has been hampered by golden algae since 2001. Habitat features were dominated by extensive bulk heading and natural shoreline.

Management History

Sportfishes in Granbury Reservoir are currently managed with statewide regulations with the exception of a 16-inch minimum length limit on largemouth bass. Important sport fish include largemouth bass and striped bass. Both have been affected by nearly annual, toxic golden alga blooms since 2001. Efforts to mitigate these losses have included collection of biannual fisheries data, annual striped bass stockings, and Florida largemouth bass stockings.

Fish Community

• Prey species: The prey base is currently stronger than ever, with numbers and catch rates of all species at or near an all-time high.
• Catfishes: Blue catfish were collected in good numbers for the first time since their original stocking in 1991. The channel catfish population looked better than ever, with individuals from 5 to 25-inches represented, and in good condition. Flathead catfish, although few in number, were also observed at higher frequencies than past surveys.
• Temperate basses: The white bass catch rate improved over previous surveys, while population size structure and condition varied. The striped bass population looked better than it has in over a decade with both good numbers of fish being recruited and good numbers of fish in the 18 to 25-inch size range. Condition indices were excellent.
• Largemouth bass: The largemouth bass catch rate was slightly higher than previous surveys. Although population structure was good, no fish were collected over 18 inches, and condition indices were noticeably lower.
• White crappie: White and black crappie are present in the reservoir in low numbers, but trap netting was not conducted in 2009. Recent anecdotal information suggested anglers were catching good numbers of legal-sized fish during spring 2010.

Management Strategies

• Sample the reservoir with electrofishing and gill netting every two years and continue assisting with golden alga research.
• Sample white crappie with trap netting and obtain a tier 3 or tier 4 largemouth bass age and growth sample in 2013.
• Adjust the annual striped bass stocking rate as needed.
• Inform controlling authorities about new exotic species threats to Texas waters, and work with those authorities to display appropriate signage, educate constituents, and understand appropriate enforcement actions.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-30-R-35 Statewide Freshwater Fisheries Monitoring and Management Program