Alan Henry Reservoir - 2021 Survey Report

Prepared by John Clayton and Caleb Huber
Inland Fisheries Division
Amarillo District, Canyon, Texas

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 Alan Henry Reservoir were surveyed in 2018, 2019, 2020, and 2021 using electrofishing, in 2019 using baited tandem hoop netting, and in 2020 using trap netting. Anglers were surveyed from April 1 through June 30 in 2018 and 2021 with a creel survey. Historical data are presented with the 2018-2021 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

Alan Henry Reservoir was constructed in 1993 on the South Fork of the Double Mountain Fork of the Brazos River. It is located 6 miles east of Justiceburg in Garza County, Texas. At conservation pool (2,220 feet above mean sea level; FMSL), Alan Henry Reservoir is a 2,884-acre impoundment. Productivity of Alan Henry Reservoir was characterized as low. Habitat features consisted of flooded terrestrial vegetation, rocks, and very small amounts of native submerged aquatic plants.

Management History

Sport fish in the reservoir included Blue Catfish, Channel Catfish, Flathead Catfish, Alabama Bass, Largemouth Bass, and White Crappie. Alabama Bass were managed with restrictive harvest regulations of 18-inch minimum length limit (MML) since their introduction in 1996 until September 1, 2011 in order to establish a viable population. In 2002, the Largemouth Bass harvest regulation was liberalized with the allowance of 2 fish under the 18-inch MML to promote recruitment of fish into size classes larger than the 18-inch MML. The Alabama Bass regulation was changed in 2011 from the 18-inch MML to be included with the Largemouth Bass regulation mentioned above (no MML on all black bass, but no more than to under 18 inches). To encourage more harvest of small black bass, the Alabama Bass regulation was further liberalized in 2019, by placing the Alabama Bass under statewide spotted bass regulations.

Fish Community

• Prey species: Gizzard Shad and Bluegill are the primary prey species in the reservoir. Threadfin Shad have been introduced to the reservoir, but their relative abundance is low.
• Catfishes: Blue Catfish, Channel Catfish, and Flathead Catfish have been observed in the reservoir, but lack of angler effort to pursue catfish species and difficulties in sampling adequate numbers indicate that all three species are present in low numbers.
• Black basses: From 2001 to 2011 electrofishing catch rates of Alabama Bass exhibited a general increase. Since 2014, while there have been spikes in the electrofishing catch rates that coincide with heavy rain event years and reservoir level increases, non-rain event years appear to have stabilized catch rates between 20 and 30 fish collected per hour of sampling. The 2021 Largemouth Bass catch rate (58.3 fish per hour) was more than double the Alabama Bass catch rate (23.7 fish per hour). All Largemouth Bass sampled were less than 18 inches in length.
• White Crappie: Forty-eight White Crappie were collected during the 2021 electrofishing survey. While crappie as large as 15 inches were surveyed, the majority of fish sampled were smaller than the 10-inch minimum length limit. An intensive trap net survey was conducted in 2020 and resulted in 341 crappie being surveyed. While the majority of fish surveyed were smaller than 10 inches, there were several fish surveyed that ranged from 10 to 13 inches. Survey results indicated that the majority of crappie appear to be concentrated in the extreme upper end of the reservoir.

Management Strategies

• Conduct additional electrofishing surveys in 2022, 2023, 2024, and 2025 to monitor continued survival and abundance of Threadfin Shad and abundance and size structure of other forage species.
• Collect black bass species during all electrofishing surveys for age and growth analysis.
• Inform the public about the negative impacts of aquatic invasive species.
• Access and vegetation surveys will be conducted in 2025.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-221-M-3 Inland Fisheries Division Monitoring and Management Program