Falcon Reservoir - 2013 Survey Report

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

This is the authors' summary from a 36-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Falcon Reservoir were surveyed using electrofishing in 2009, 2011, 2013-2014, gill nets in 2010, 2012, 2014, and trap nets in 2009-2010 and 2012-2013. Historical data are presented with the 2013-2014 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 (6/2009-5/2014),water level ranged from 41 feet below (5/2013) to 4 feet above (10/2010) conservation pool elevation. Flooded terrestrial vegetation is the predominant structural habitat for fish.

Management History

Fish harvest is regulated by Texas Parks and Wildlife Department according to the standard statewide restrictions and is unregulated by Mexico. A substantial commercial gill net fishery exists on the Mexico-side of the reservoir targeting primarily Blue Tilapia, Catfishes, and rough fish species. Striped Bass were stocked prior to 2003 to provide an additional angling opportunity, but were discontinued because of low water level and minimal angler utilization. White Bass and White Crappie stockings were conducted in the 2000s in an attempt to restore these two populations. Florida Largemouth Bass (FLMB) fingerlings have been stocked annually in recent years to increase FLMB genetic introgression and in turn, Largemouth Bass trophy potential.

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 species.
• Alligator Gar: Abundance has reportedly increased in recent years. Catches of state and world record size fish were reported in 2013, but these were unconfirmed.
• Catfishes: Blue Catfish abundance increased during the study period, but the population was comprised of a larger proportion of small fish than in the past. Channel Catfish abundance declined during the study period and the population was dominated by small fish. Catfishes accounted for a decreased proportion of the total fishing effort.
• White bass: White Bass were first collected in gill nets in 2014 after not having been collected since 1995 due to the effects of an extended low water period coinciding with intense Mexican commercial netting.
• Largemouth bass: Largemouth Bass relative abundance peaked in 2009-2011, then declined by about 60%. Fishing effort increased by 135%, catch by 79%, and harvest by 95% in 2011 over 2006.
• Black crappie: Black Crappie have been reestablished in the reservoir since 2009, however relative abundance remains low.

Management Strategies

Stock FLMB annually, increase frequency of surveys to monitor Largemouth Bass and White Bass populations, and conduct an intensive study of Alligator Gar.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-221-M-4 Inland Fisheries Division Monitoring and Management Program