H-4 (Gonzales) Reservoir - 2007 Survey Report

Prepared by John Findeisen and Greg Binion
Inland Fisheries Division
District 1-E, Mathis, Texas

This is the authors' summary from a 23-page report. For a copy of the complete report, use the download link in the sidebar.

H-4 Reservoir was surveyed in the fall 2007 using trap nets and electrofishing and in the spring 2008 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

H-4 is a 696-acre reservoir on the Guadalupe River in Gonzales County and is controlled by the Guadalupe-Blanco River Authority (GBRA). The reservoir was impounded in 1931 to provide water for a hydroelectric plant and recreational uses. The substrate is composed primarily of silt, sand, clay, and some gravel and rock. Angler and boat access was limited to only one pay-to-use boat ramp. There were no handicap specific facilities. At the time of sampling, the habitat was composed of boat docks, stumps, floating-leaved vegetation, limited submersed and emergent vegetation, and water hyacinth.

Management History

Important sport fish species include channel catfish, largemouth bass, and crappie. Anglers have reported catching white, palmetto and striped bass from this reservoir but these species were not collected in gill net surveys. Palmetto and striped bass migrate downstream from a stocked upstream reservoir (Canyon Lake). Flathead catfish were present in the reservoir and blue catfish have been stocked in this reservoir but have yet to become the dominant catfish species as seen in other reservoirs throughout Texas. The 2004 management plan focused on working with GBRA on constructing a new boat ramp and increasing bank access and monitoring nuisance aquatic vegetation. The GBRA does not own enough land surrounding the reservoir to construct a new boat ramp and increase bank access. The GBRA contracted a certified commercial applicator to conduct herbicide treatments, specifically for water hyacinth, since the last report. Beginning in 2007 GBRA and TPWD started working cooperatively towards a better focused control of water hyacinth. A nuisance aquatic management plan was drafted in January 2008. Hydrilla, once present in the reservoir, was last observed in 2004.

Fish Community

• Prey species: Gizzard shad, threadfin shad, and several sunfish species were the primary forage species available to predators. Relative abundance of gizzard shad has continuously increased since 2003. Additionally, the percentage of gizzard shad available to most predators has also increased.
• Catfishes: Blue, channel, and flathead catfish were present in the reservoir with channel catfish being the dominant species. The majority of channel catfish collected were legal size (> 12 inches) with several over 20 inches in total length.
• Black basses: Largemouth, Guadalupe, spotted, and smallmouth bass were present in the reservoir with largemouth bass being the most abundant. Recruitment of largemouth bass appears to be limited as very few adult-sized individuals were collected. Complex habitat types such as fallen trees and submersed aquatic vegetation were insufficient to support abundant black bass populations.
• Crappie: White and black crappie were present in the reservoir with white crappie being the most abundant. Poor habitat may be limiting crappie recruitment as well.

Management Strategies

• Continue managing the fish populations under current regulations.
• Continue to work with GBRA on controlling water hyacinth, enhance habitat, and monitor the spread and colonization of East Indian hygrophila. Introductions of native aquatic vegetation will be explored and implemented once water hyacinth is controlled. East Indian hygrophila has become established in the boat ramp slough; however, floating fragments were found throughout the reservoir.
• Additional spring electrofishing surveys will be conducted to further assess largemouth bass, sunfish, and shad populations.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-30-R-33 Statewide Freshwater Fisheries Monitoring and Management Program