Coleman Reservoir - 2004 Survey Report

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Prepared by Mukhtar Farooqi and Spencer Dumont
Inland Fisheries Division
District 1-B, Abilene, Texas

This is the authors' summary from a 20-page report. For a copy of the complete report, use the download link in the sidebar.

Coleman Reservoir was surveyed in fall 2004 using electrofishing and trap nets, and in spring 2005 using gill nets. This report summarizes the results of the surveys and contains a management plan for the reservoir based on those findings.

Reservoir Description

Coleman Reservoir is a 2,000-acre impoundment owned and controlled by the city of Coleman, Texas. It was impounded in 1966 on Jim Ned creek, a tributary of the Colorado River. It is located 11 miles north of Coleman. The reservoir provides municipal and industrial water supply for the city of Coleman and is also used for flood control and recreation. Topography grades from gentle to moderate relief. Land use around the reservoir includes residential and agriculture. The habitat in the reservoir at the time of sampling consisted mainly of rocky structure, standing timber, and aquatic vegetation (lotus, stargrass and floating leaf pondweed). Water levels had steadily declined after 1998 to a low not observed since the reservoir was impounded. However, this trend was reversed in July of 2002 when the reservoir filled and has been at or close to conservation level since that time. Coleman Reservoir is a study site for the habitat enhancement initiative, which began in 1998.

Fish Community

• Prey species: Electrofishing catch rates of bluegill, sub-stock gizzard shad, and threadfin shad were 224.0/h, 29.5/h, and 210.0/h, respectively. Index of vulnerability (IOV) for gizzard shad was relatively low, indicating that 36% of gizzard shad were available to existing predators. The IOV from the two previous survey years ranged from 86 to 94. In addition, the catch per unit effort (CPUE) of gizzard shad was considerably lower than that recorded in previous surveys. Bluegill CPUE in 2004 increased relative to that recorded in the 2000 survey. In essence the population size structure reflects that observed in 1997, i.e. before the 1999-2002 drought was in effect. Electrofishing catch rate of threadfin shad improvedcompared to that recorded in 2000 (7.0/h) [Dumont 2001] and 1997 (148.7/h) [Dumont and Jons 1998].
• Catfishes: The gill net catch rate of channel catfish was 2.0/NN in 2005 compared to catch rates ranging from 0.8 to 1.4/NN from the surveys in 1997 and 2001. Relative abundance has been consistently low. Channel catfish were last stocked in 2003.
• Palmetto bass: The gill net catch rate of palmetto bass was 10.4/NN in 2005 and is essentially at the same level as that recorded in previous years. Catch rate ranged from 11.8/NN to 12.3/NN from 1997 to 2001. The bulk of the fish were in the 19 inches to 23 inches size range. Relative weight (Wr) estimates were above 90 for the 19 inches to 22 inches size range. There was somewhat of an improvement in Wr compared to the results of the 2001 survey and larger fish were present. Hybrid striped bass were stocked in 2004, and prior to that the last stocking took place in 1998, hence the absence of younger year classes.
• Largemouth bass: Overall, the population characteristics for largemouth bass were similar to that recorded in the 2000 survey. The total CPUE of largemouth bass in 2004 was 142.0/h compared to 139.0/h in 2000. The catch rate for stock length largemouth bass (69.0/h) was slightly down from 2000 (78.0/h), continuing the downward trend from 1997. Population size structure was adequate with a proportional stock density (PSD) of 45 and relative stock density (RSD-P) of 6. The body condition of largemouth bass from 8 inches to 18 inches was adequate (Wr generally ranging between 91 to 97), showing some improvement since the 2000 survey was conducted (especially with regard to the 13-inch to15-inch size group). With the exception of two fish (age 5 and 6) all individuals aged were 2 years old or younger and their growth rate was in line with that recorded from previous surveys. Electrophoresis in 2004 indicated a 46.2% frequency of Florida largemouth bass alleles with 15% having a Florida largemouth bass genotype. The latter has increased since the 2000 (6.7% Florida genotype) and 1997 (3.3% Florida genotype) surveys were conducted.
• White crappie: Relative abundance has increased steadily since 1997. In 2004, the trap net catch rate of white crappie was 9.6/NN and stock CPUE was 9.4/NN. The RSD-P was 33; a decrease compared to 2000 (RSD-P=51). Body condition and growth rates were reasonable; Wr ranged from 89 to 97. Mean length at ages 1 and 2 was in line with that of previous surveys. By age 2, crappie were long enough for harvest.

Management Strategies

Stock palmetto bass biennially at a rate of 5/acre. Conduct general monitoring with trap nets, gill nets and electrofishing surveys in 2008-2009.

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