Falcon Reservoir - 2015 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 Falcon Reservoir were surveyed in 2014-2016 using electrofishing since the last report (July 2014). Anglers were surveyed from January through June 2016 with a creel survey. Historical data are presented with the 2015-2016 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

Falcon Reservoir (83,654 acres when full) borders Mexico and was constructed in 1954 on the Rio Grande River. The reservoir experiences extreme water level fluctuations due to variable rainfall and water releases for downstream agricultural irrigation. During the survey period (6/2014 to 5/2016), water level steadily increased inundating terrestrial vegetation. Flooded terrestrial vegetation was present in 39% of the Texas-side of the reservoir in September 2015.

Management History

Fish harvest is regulated according to the standard statewide restrictions, except for Alligator Gar. The daily bag limit for Alligator Gar is 5 fish/day. On the Mexico side, fish harvest is unregulated and a substantial commercial gill net fishery exists targeting primarily Blue Tilapia, catfishes, and rough fish species. Florida Largemouth Bass (FLMB) fingerlings have been stocked annually in recent years to increase FLMB genetic introgression and in turn, Largemouth Bass trophy potential. Giant salvinia was found growing near a boat ramp in 2016 and was removed.

Fish Community

• Prey species: Gizzard Shad, Threadfin Shad, Bluegill, and Blue Tilapia are the primary forage species, and were present in sufficient quantity and size to support predator populations.
• Alligator Gar: Population size and age structure for this species is excellent. The water body record was increased with a fish weighing 249 lbs. taken by bow fishing in 2014. From January to June 2016, anglers expended 1,668 hours bow fishing for the species and harvested 187 Alligator Gar.
• Catfishes: Blue Catfish is the predominant catfish species in the reservoir and their relative abundance has remained consistent in recent years. A new water body record was set for Blue Catfish with a fish weighing 60 lbs. taken by a rod and reel angler in 2016.
• White bass: Relative abundance of White Bass remained low. Although there was no angling effort directed at this species, 507 White Bass were incidentally caught and harvested.
• Largemouth bass: Relative abundance of Largemouth Bass has increased, recovering from low abundance in 2013-2014. The population is mostly comprised of fish <12 inches total length. From January to June 2016, 115,115 were caught by anglers, and one of every 14 fish, on average, exceeded 4.0 lbs.
• Black crappie: Relative abundance of Black Crappie remained low. From January-June 2016, anglers expended 1,342 h fishing for the species and harvested 676 Black Crappie.

Management Strategies

Concerning Largemouth Bass, stock FLMB annually, frequently monitor population, estimate genetic introgression of FLMB into the population, and explore via simulation model the potential effectiveness of alternative harvest regulations. Assess Alligator Gar population size and age structure to determine effects of daily bag limit increase. Monitor for presence of invasive aquatic species and conduct control activities as needed.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-221-M-6 Inland Fisheries Division Monitoring and Management Program