Falcon Reservoir - 2009 Survey Report
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Prepared by Randy Myers and John Dennis
Inland Fisheries Division
District 1-D, San Antonio, Texas
This is the authors' summary from a 25-page report. For a copy of the complete report, use the download link in the sidebar.
Fish populations in Falcon Reservoir were surveyed in 2007 and 2009 using electrofishing and trap nets and in 2006 and 2010 using gill nets. This report summarizes the results of the surveys and contains a management plan for the reservoir based on those findings.
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. Water level declined to a record 54 feet low in 2002 and steadily increased to 2.3 feet above conservation pool elevation in 2009. As a result of the water level increase, flooded terrestrial vegetation is currently the predominant structural habitat for fish.
Fish harvest is regulated by Texas Parks and Wildlife Department (TPWD) 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 with blue tilapia, catfishes, and rough fish species comprising most of the catch. Striped bass, palmetto bass, and smallmouth bass were historically stocked to provide additional angling opportunities, but stockings were discontinued because of low fish survival or low angler utilization. White bass and white crappie stockings were conducted in the 2000s in an attempt to restore these two populations which historically supported popular fisheries but were decimated during the 1990s due to an extended period of low water level and commercial netting. Largemouth bass, blue catfish, and bluegill were stocked from 2003-2005 to offset population impacts caused by the previous low water level. In 2009, Florida-strain largemouth bass (FLMB) were stocked to increase the percentage of pure Florida bass in the reservoir, and thus trophy potential.
- Prey species: Shad species, sunfish species, and blue tilapia are the principal forage fishes in the reservoir. Fish population survey data suggest that prey abundance and size are not limiting predator fish abundance and growth.
- Catfishes: Blue catfish relative abundance doubled since 2004 and the population contains fish >30 inches in total length (TL). Channel catfish relative abundance remained similar since 2004 and the population is dominated by sublegal size fish (<12 inches TL).
- Temperate basses: No white and striped bass were collected during population surveys conducted from 2006 to 2010 suggesting the white bass population remains depleted and previously stocked striped bass no longer exist in the reservoir.
- Largemouth bass: Population survey data indicate increased relative abundance and excellent population size structure, with fish attaining legal harvestable size (>14 inches) during their second growing season. The reservoir currently supports an exceptional largemouth bass fishery.
- White crappie: Relative abundance increased tremendously in 2009 and growth was excellent, with 2009 year-class fish averaging 9.6 inches in December 2010.
Improve genetic introgression of FLMB, promote the white crappie fishery, closely monitor the white crappie and largemouth bass populations, quantify the white crappie and largemouth bass fisheries, and provide educational assistance to minimize largemouth bass tournament mortality.
Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-30-R-34 Statewide Freshwater Fisheries Monitoring and Management Program