Mexia Reservoir - 2003 Survey Report

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Prepared by Michael S. Baird and John Tibbs
Inland Fisheries Division
District 2-B, Waco, Texas

This is the authors' summary from a 32-page report. For a copy of the complete report, use the download link in the sidebar.

Mexia Reservoir was surveyed in the fall of 2003 by boat electrofishing and trap netting, and spring of 2004 by gill netting. This report summarizes most recent survey results and contains a management plan for the reservoir based on those findings.

Reservoir Description

Mexia Reservoir is supplied by the Navasota River within the Brazos River Basin, Limestone County. The reservoir is used as a municipal water supply, and for recreation. The 897-acre impoundment has a drainage area of 200 square miles, a storage capacity of 10,000 acre-feet, and a shoreline length of 16 miles. Mean and maximum depths are 10.0 and 20.0 feet respectively. Shoreline fish habitat consisted of boat docks, rocky shoreline, and inundated stumps in the back of coves. Bank fishing is limited to only a few areas on the reservoir. Boat access (one ramp) on the reservoir is adequate, and there are currently no handicap-specific facilities.

Fish Community

• Prey species: Gizzard shad continue to be the dominant forage species in the reservoir. The total electrofishing catch rate in 2003 was 505.0/hour. The index of vulnerability (i.e., the percentage of individual gizzard shad less than 8 inches total length, thought to be vulnerable to predation) or IOV was 88. The electrofishing catch rate of threadfin shad was 2,007/hour which is much higher than the 1999 survey in which 256.0/hour were collected. This is a tremendous amount of forage available to predators. Bluegill were caught at a rate of 86.0/hour while electrofishing. This compares favorably with the average of the previous three surveys (68.9/hour). No bluegill exceeded six inches in length, indicating good forage availability for predators.
• Catfishes: Blue catfish were not collected during 2004 gill netting despite being caught at a rate of 1.8/net night in 1999. Blue catfish were initially stocked in 1975, and stocked again in 1995 and 1996. Flathead catfish were not collected during gill netting in 2004. Channel catfish were collected at a rate of 6.6/net night during 2004 gill netting similar to the average of the previous three surveys (5.7/net night). The vast majority of fish collected exceeded the minimum length limit of 12 inches.
• White bass: White bass were collected during 2004 gill netting at a rate of 2.6/net night. All exceeded the minimum length limit of 10 inches. White bass catch rates vary quite a bit among previous samples (1993, 0.4/net night; 1996, 5.0 net/night; 1999, 1.0 net/night).
• Largemouth bass: Largemouth bass were collected at a rate of 62.0/hour during 2003 electrofishing. This is similar to the average of the previous three surveys (68.2/hour). Relative weights were excellent, ranging from 95 to 120 throughout the sizes represented in the sample. Electrophoretic analysis showed levels of Florida alleles in the sample (25.0%) were similar to those from1999 (27.6%). In addition, pure Florida fish were sampled for the first time (4%).
• White crappie: There is a large number of white crappie in Mexia reservoir. Trap netting during 2003 collected white crappie at a rate of 36.4/net night, somewhat less than the average for the previous three surveys (50.7/net night), but impressive none-the-less. The relative stock density of 10-inch fish and larger (RSD10) of 53 indicates over half the stocksize (>5”) or larger white crappie were vulnerable to harvest. Growth rates were good, with the average white crappie reaching legal-size sometime in their second year of life.

Management Strategies

Based on current information, Mexia Reservoir should continue to be managed with current regulations. Supplemental stocking of blue catfish will be considered in 2008 if adequate recruitment is not documented in the spring 2008 gill netting sample. Annual news releases regarding the excellent white crappie population will be issued to generate interest in angling for this popular sport fish.

Performance Report as required by Federal Aid in Sport Fish Restoration Act Texas Federal Aid Project F-30-R-29 Statewide Freshwater Fisheries Monitoring and Management Program