Sheldon Reservoir - 2008 Survey Report

Prepared by Jeff Henson and Mark Webb
Inland Fisheries Division
District 3-E, Bryan, Texas

This is the authors' summary from a 19-page report. For a copy of the complete report, use the download link in the sidebar.

Fish populations in Sheldon Reservoir were surveyed in 2008 using electrofishing and in 2009 using gill netting. This report summarizes the results of the surveys and contains a management plan for the reservoir based on those findings.

Reservoir Description

Sheldon Reservoir is a 1,229-acre reservoir on Culpepper Bayou in Harris County, Texas, lying within the Sheldon Wildlife Management Area. The lake has a drainage area of 4.0 square miles and a shoreline length of 13.1 miles. The reservoir has a mean depth of 3 feet and a maximum depth of 20 feet.

Management History

Sheldon Reservoir is a very important asset to Texas Parks and Wildlife and to the people of Houston. To make the most of this resource Inland Fisheries Division has worked closely with Sheldon Reservoir State Park’s Staff and Infrastructure Staff to improve the reservoir in conjunction with the development of the Sheldon Education Center. Heavy infestations of hydrilla, giant salvinia, and water hyacinth have greatly impeded recreational use at Sheldon Reservoir. Multiple herbicide treatments over several years have been unsuccessful in maintaining control of noxious vegetation.

Fish Community

• Prey species: Gizzard and threadfin shad are no longer present in electrofishing samples. Reduced sampling efficiency due to low water and extensive vegetation coverage may account for the lack of shad species collected. In addition, heavy infestations of aquatic plants reduce the quantities of free-floating microscopic algae necessary for shad to thrive. The catch rate of bluegills in 2008 was 8.0/h, much lower than in 2004 (42.0/h). Redear sunfish are also available as prey. The catch rate in 2008 was 22.7/h, down from 2004 (84.0/h). Again, the lower catches of sunfish are probably due to low efficiency caused by excessive vegetation.
• Catfishes: Historically, blue and channel catfish were present in Sheldon Reservoir; however, only channel catfish were captured in the 2009 gill net survey. Numbers are low, but individuals 29 inches in length were observed.
• Largemouth bass: Electrofishing catch rate of largemouth bass dropped from 249.0/h in 2004 to 21.3/h in 2008. Excessive vegetation hampered sampling efficiency so the 2008 catch rate may not represent an actual population decline.
• Crappie: Because of the vegetation problem in the reservoir, no trap net survey was conducted in 2008. The trap net catch rate of white crappie in 2004 was 0.4 /nn, down drastically from 20.4/nn in 2000. The catch in 2000 was very well distributed across all sizes classes from 2 to 14 inches indicating population expansion over the past several years. Black crappie were absent in the 2004 sample. White crappie attained legal harvestable size (10 inches) by about age 3.

Management Strategies

The primary challenge at Sheldon Reservoir is aquatic vegetation management. We are continuing to implement integrated pest management strategies to address the problem. Strategies include chemical treatments, biological control insects, and triploid grass carp. Fish management strategies will be implemented once the vegetation growth is controlled. These strategies will include habitat enhancement and stocking Florida largemouth bass.

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