Casa Blanca Reservoir - 2006 Survey Report

Prepared by Randy Myers and John Dennis
Inland Fisheries Division
District 1-D, San Antonio, Texas

This is the authors' summary from a 22-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Casa Blanca Reservoir were surveyed using electrofishing and trap nets in 2004 and 2006, and gill nets in 2003, 2005, and 2007. This report summarizes the results of the surveys and contains a management plan for the reservoir based on those findings.

Reservoir Description

Casa Blanca is a 1,680-acre reservoir located near Laredo, Texas, in the Rio Grande River watershed. The reservoir and associated Lake Casa Blanca State Park have been managed by Texas Parks and Wildlife Department since 1990. Water level records are not kept for this reservoir. Maximum water level fluctuation during the study period was observed to be about 2 feet and water level was sufficient proving adequate angler and boat access. Handicap specific facilities were not present. At the time of sampling, the habitat was primarily rocky shoreline, flooded terrestrial vegetation and native emergent vegetation.

Management History

Important sport fishes include largemouth bass, catfishes, white crappie, and palmetto bass. Harvest of all sport fish species except largemouth bass has been regulated according to statewide size and daily bag limits. Largemouth bass harvest is currently regulated with an 18-inch minimum size limit and a 5-fish daily bag limit. Palmetto bass have been stocked regularly with stockings occurring in four years since 2000. Florida largemouth bass fingerlings were last stocked in 2004.

Fish Community

• Prey species: Gizzard shad, threadfin shad, and bluegill form the reservoir’s forage base, however gizzard shad abundance was considerably lower in 2006 compared to previous years.
• Catfishes: Population abundance fluctuated during the study period for both blue and channel catfish, with blue catfish more abundant than channel catfish. Population size structure remained poor for channel catfish and some improvement was noted for blue catfish size structure in 2007.
• Temperate basses: The reservoir currently supports an abundant palmetto bass population relative to previous years, which is a result of stockings conducted in 2004 and 2005.
• Largemouth bass: Relative abundance of largemouth bass fluctuated during the survey period with highest abundance in 2004. Although the population was dominated by small fish, 4 fish >13 lbs. were caught from the reservoir and donated as ShareLunkers since 2004.
• White crappie: Relative abundance of white crappie also fluctuated during the survey period. Population size structure remained similar throughout the survey period, with most fish measuring <10 inches in 2004 and 2006.

Management Strategies

• Continue to use and evaluate the effectiveness of the 18-inch minimum size limit and 5-fish daily bag limit for largemouth bass.
• Continue to stock palmetto bass, but at a reduced rate and frequency.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-30-R-32 Statewide Freshwater Fisheries Monitoring and Management Program