Amistad Reservoir - 2014 Survey Report

Prepared by Randall A. Myers and John A. Dennis
Inland Fisheries Division - San Antonio District

This is the authors' summary from a 39-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Amistad Reservoir were surveyed in 2014-2015 using electrofishing and gill netting. Anglers were surveyed from January to June 2015 with a creel survey. Historical data are presented with the 2014-2015 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

Amistad Reservoir is a 63,680 acre Texas-Mexico border impoundment on the Rio Grande River. It was constructed in 1969 and managed by the International Boundary and Water Commission to provide water for irrigation and hydro-electric power generation. Boat and angler access is excellent; the National Park Service (NPS) maintains 11 public boat ramps. Water level declined from full pool in 2011 to a record 61 feet low in 2013. Water level has increased since 2013 and has remained at 28-30 feet low since December 2014. Aquatic vegetation coverage was lower in 2011-2014 than in previous years, and hydrilla is the predominant species.

Management History

Important sport fishes include Largemouth Bass, catfishes, Striped Bass, and White Bass. Striped Bass were stocked in most years since 1974. Florida Largemouth Bass (FLMB) were stocked periodically from 1975 to 2006 and annually since 2010 to improve FLMB introgression and trophy Largemouth Bass potential. Angler harvest of all sport fishes has been regulated according to statewide size and bag limits. Since 2004, the NPS has regulated largemouth bass tournaments via a tournament permitting program.

Fish Community

• Prey species: Shad and sunfish spp. comprise the primary prey in the reservoir. Relative abundance of aforementioned prey was low in recent years.
• Catfishes: Channel Catfish is the predominant catfish species present in the reservoir. Relative abundance of Channel Catfish has been consistently low since 2011. Catfish angling annually accounted for 1.1-7.3% of total angling effort at the reservoir.
• Temperate basses: White Bass and Striped Bass relative abundance has been consistently low since 2011. White Bass attain legal harvestable size between age 1 and 2. Temperate bass angling annually accounted for 1.4-6.5% of total angling effort at the reservoir.
• Black basses: Largemouth Bass relative abundance has declined in recent years due to extreme water level fluctuation and an associated decrease in aquatic vegetation coverage. Largemouth Bass angling annually accounted for 84-95% of total angling effort at the reservoir. Catch of Smallmouth Bass increased considerably in recent years. Black bass tournament angling comprises a substantial portion of the fishery.

Management Strategies

• Continue to provide a Striped Bass fishery supported by annual stockings.
• Continue stocking Florida Largemouth Bass annually to maintain high FLMB introgression and trophy potential.
• Work cooperatively with Amistad Reservoir stakeholders to address issues that arise.
• Conduct electrofishing, gill net, and vegetation surveys every other year and a creel survey every four years.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-221-M-5 Inland Fisheries Division Monitoring and Management Program