Cooper Reservoir - 2003 Survey Report
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Prepared by Randall A. Myers and Kevin W. Storey
Inland Fisheries Division
District 3-B, Tyler, Texas
This is the authors' summary from a 23-page report. For a copy of the complete report, use the download link in the sidebar.
Cooper Reservoir was surveyed from June 2003 to May 2004 using electrofishing, trap netting, and gill netting. This report summarizes the results of the surveys and contains a management plan for the reservoir.
Cooper Reservoir is located in Delta and Hopkins Counties, Texas, on the Middle and South Forks of the Sulphur River. It was constructed for water supply, flood control, and recreation by the U. S. Army Corps of Engineers. Angler access is good with five publicly accessible boat ramps and bank angling facilities in both units of Cooper Lake State Park. The shoreline is primarily featureless mud bank and the littoral area contains limited amounts of aquatic vegetation. Flooded timber occurs in most of the creeks, along the shoreline, and in approximately 50% of the upper reservoir. Decreased rainfall (Appendix 4) resulted in extremely low water levels during the 2003-2004 study period, averaging 3.86 feet below conservation pool elevation (Appendix 5). The low water level could negatively impact previously conducted native aquatic plant establishment efforts.
- Prey species: Gizzard shad and threadfin shad are the most important prey species for predators in Cooper Reservoir. Electrofishing CPUE of gizzard shad was lower in 2003 (93.5 fish/hour) than in 1999 (298.0 fish/hour) and 1996 (132.0 fish/hour). Based on the size structure of the population, the majority of gizzard shad are available as prey for adult largemouth bass; the mode of the 2003 length frequency distribution was 7 inches. Electrofishing CPUE of threadfin shad in 2003 was 142 fish/hour. Electrofishing CPUE of bluegill was greater in 2003 (36.5 fish/hour) than in 1999 (7.0/hour), but much lower than in 1996 (284 fish/hour). It is unlikely that a substantial sunfish fishery occurs because no fish >6 inches were collected in 1996, 1999, and 2003 electrofishing surveys.
- Catfishes: Channel catfish relative abundance has remained consistent, whereas blue catfish relative abundance has increased in Cooper Reservoir. Gill net CPUE of channel catfish in 2004 (4.1 fish/netnight) was similar to in 2002 (4.2fish/net-night) and lower than in 1999 (7.4 fish/net night). The proportion of quality-size channel catfish (> 16 inches) to stock-size fish (>11 inches), however, was greater in 2004 (PSD = 50) than in 2002 (PSD =30) and 1996 (PSD = 37). Channel catfish exhibit a moderate growth rate in Cooper Reservoir and grew to legal-length (>12 inches) during their fourth year. Gill-net CPUE of blue catfish in 2004 was substantially higher in 2004 (9.13 fish/net-night) than in 2002 (1.3 fish/net-night) and 1999 (1.3 fish/net-night). Blue catfish PSD in 2004 was 26 and 41% of the fish sampled were less than stock size (12 inches). Cooper Reservoir blue catfish exhibit moderate to rapid growth with most attaining legal-length (>12 inches) during their third year of life. In June 2003, TPWD Resource Protection staff investigated a fish kill that primarily affected catfish spp. Bacterial infection was suspected in causing the deaths of an estimated 1631 blue catfish and 526 channel catfish. Consistent (channel catfish) and increased (blue catfish) catch in gill nets in 2004 compared to previous years suggest that the 2003 fish kill had little, if any, negative effect on catfish spp. population abundance. Two flathead catfish were collected in 2004 gill-net samples. New water body records were set for channel, blue and flathead catfish during the 2003-2004 study period.
- Temperate basses: In 2004, white bass abundance returned to pre-fish-kill level and hybrid striped bass relative abundance was at a record high. In spring 2002, shortly after a white bass-specific kill in May 2001, gill-net CPUE of white bass was low (1.9 fish/net-night). Gill-net CPUE increased in 2004 to 10.4 fish/net-night, similar to 1999 (10.1 fish/net-night). The cause of the 2001 fish kill was not determined and its effects, although severe, were short-term. White bass exhibited moderate to rapid growth in Cooper Reservoir with most attaining legal-length (>10 inches) during their second year of life. Recent hybrid striped bass stockings were very successful, especially the 2002 stocking. Gill-net CPUE of hybrid striped bass was considerably greater in 2004 (18.7 fish/net night) compared to in 2002 (0.1 fish/net-night) and 1999 (1.7 fish/net night). The population was dominated by age-2 fish (mean TL = 17.8 inches) which were stocked in 2002 from boat ramps.
- Black bass: Electrofishing CPUE of largemouth bass in fall 2003 (11.5 fish/hour) was slightly lower than in 2001 (20.5 fish/hour) and similar to 1999 (11.0 fish). Low sampling efficiency and the severe low water level at the time of sampling in 2003 made it difficult to evaluate for changes in largemouth bass relative abundance. Even though electrofishing sampling has provided little information on the largemouth bass population, the lake has historically supported a popular fishery. However, comments from local anglers suggested largemouth bass angling success declined in 2003-2004 due to the low water level. Largemouth bass exhibited slow to moderate growth rates attaining legal-length (>18 inches) during their fifth year of life. The Florida largemouth bass allele frequency in 2003 (39.7%) was similar to that in 2000 (41%). Fingerling FLMB stockings were conducted in 2002 and 2003.
- Crappie: Trap net CPUE of white crappie in 2003 (8.9 fish/net-night) was almost twice that in 1999 (4.7 fish/net-night). Additional sampling conducted in fall 2001 indicated an extremely abundant white crappie population (67.5 fish/net-night) consisting primarily of age-1 and age-2 fish (<8 inches). Fish from these two strong year classes (2000 and 2001) have recruited to the fishery, and are well represented in the 2003 population sample as RSD-P was 65. Although creel sampling was not conducted at Cooper Reservoir, anglers reported excellent crappie fishing during the 2003-2004 study period. White crappie in Cooper Reservoir exhibit moderate growth rates attaining legal-length (>10 inches) during their third year of life. Black crappie are present in Cooper Reservoir, but in very low abundance; trap net CPUE in 2003 was 0.20 fish/net-night.
All species should continue to be managed under current harvest regulations. Gill net sampling will be conducted biennially to monitor catfishes and temperate bass populations. Electrofishing will be conducted biennially to monitor largemouth bass population trends and to evaluate the success of FLMB stockings.
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