Ray Roberts Reservoir - 2003 Survey Report

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Prepared by Bruce Hysmith and John H. Moczygemba
Inland Fisheries Division
District 2-A, Pottsboro, Texas

This is the authors' summary from a 46-page report. For a copy of the complete report, use the download link in the sidebar.

Ray Roberts Reservoir was surveyed in 2003 with trap nets and electrofisher, and in 2004 with gill nets. This report summarizes the results of these surveys and contains a management plan for the reservoir based on these findings.

Reservoir Description

Ray Roberts Reservoir is a 35,719-acre impoundment on the Elm Fork Trinity River north of Dallas-Fort Worth in Denton, Grayson, and Cooke Counties. It was constructed in 1987 by the U.S. Army Corps of Engineers for municipal water supply, flood control, and recreation. Ray Roberts has a drainage area of approximately 692 square miles, a shoreline length of 207 miles, and a shoreline development index of 8.6. Principal tributaries are Isle du Bois, Buck, Range, Wolf, Indian, and Spring Creeks. Approximately 38% of the reservoir is < 15 feet deep. Average rainfall is 36 inches annually. The lake level fluctuated approximately 3.5 feet during the period June 2002 through May 2004. There are seven boat ramps, eight public access areas and angler access at eight bridge crossings, and handicap access is adequate with boarding piers at all boat ramps and a long fishing pier at the Isle du Bois Unit of the Ray Roberts State Park. A park access fee of $5 per person per day or $60 annually (from month of purchase) is required before launching a boat at all sites except Pecan Creek Park off FM3002 on the Elm Fork Trinity River arm of the lake.

Fish Community

• Prey species: Historically, the electrofishing catch rate of gizzard shad has remained at or above 100.0/hour. The 2003 electrofishing catch rate of gizzard shad was 127.0/hour, a decrease from 1998, and below the district average of 173.7/hour for 2003. The Index of Vulnerability (IOV, Di Cenzo et al. 1996) for gizzard shad was 25, a decrease from the IOV of 72 in 1998. The 2003 electrofishing catch rate for bluegill was 123.0/hour, a decrease from 1998, and below the district average of 146.7/hour for 2003. Ninety-two percent of the sample population was < 4 inches total length (TL). The electrofishing catch rate for threadfin shad was 189.5/hour in 2003, which was the highest catch rate on record.
• Catfishes: Blue catfish first appeared in this reservoir in 1998. Their abundance increased as indicated by the 2004 gill net catch rate of 1.4/net night, equal to the district average for 2004. The sample population was comprised of 7- to 26-inch groups and 67% of the sample population was legal size (> 12 inches TL). Remaining relatively stable since 1995, the gill net catch rate of channel catfish in 2004 was 5.5/net night, similar to the district average of 5.4/net night. The sample was dominated by 7- to 9-inch groups. The sample population was made up of 31% legal fish (> 12 inches TL). Relative weights varied greatly by inch-group, but seldom lower than 90. Directed angling effort for catfishes (blue and channel catfish combined) declined in 2000, according to annual creel survey statistics. Angler catch rate and harvest rate for catfishes declined after 1998. The angler harvest rate of channel catfish in 1998 was 1/hour, in 1999 0.7/hour, and in 2000 0.5/hour. The average size harvested was 15 inches. Results from the spring quarter only for 1998, 1999, 2001, and 2004 indicated directed effort for “catfishes” dropped in 1999, but increased in 2001 and 2004. The catch rate and harvest rate for combined catfishes were highest in the spring of 2001. Sizes of channel catfish harvested during these four spring quarters were similar to the annual creel survey analysis.
• White bass: The 2004 gill net catch rate for white bass of 1.8/net night was above the district average of 1.2/net night. The sample population had 74% legal-size fish (> 10 inches TL). Relative weights varied by inch-group, but remained around 80. White bass grew to 10 inches TL in less than 2 years. Annual creel survey statistics indicated a decline in directed angling effort for white bass during 1998 through 2000. However, angler harvest was highest in 2000. The angler harvest rate of white bass was 0.7/hour in 1998, 0.5/hour in 1999, and 1/hour in 2000. The average size harvested was 12 inches. Results from the spring quarter creel survey for 1998, 1999, 2001, and 2004 indicated an increase in angler harvest rate from the spring of 1999 to the spring of 2004; the highest harvest rate was recorded in the spring of 2004. Anglers were harvesting almost 2 white bass/hour.
• Largemouth bass: The 2003 electrofishing catch rate for spotted bass was 15.0/hour, which is the highest on record. A strong year-class of young-of-the-year (YOY) was observed in 2003. Relative weights of stock-size and larger was around 90. The 2003 electrofishing catch rate for largemouth bass of 85.0/hour, was below the catch rate in 2002, but higher than the district average of 82.0/hour for 2003. From 1988 to 2003, nine electrofishing surveys were conducted with an average catch rate of 102.7/hour. Five of those nine surveys produced electrofishing catch rates of 86.7/hour or below. The lowest electrofishing catch rate on record was 48.0/hour in 2000. Despite the apparent absence of big largemouth bass, population dynamics seem normal. A largemouth bass virus (LMBV) survey in 2003 showed a 1.7% incidence of LMBV in the 60 largemouth bass collected. The reservoir was opened to the public January 1, 1990 with a 14-inch minimum length limit, 5 fish daily bag. The regulation has undergone numerous changes since to ensure protection of big fish in the population. Currently the harvest regulation is a 14- to 24-inch slot length limit, 5 fish daily bag limit (only 1 fish > 24 inches). Since slot length limits permit the harvest of smaller fish, 98% of the sample population was legal to harvest. Growth was generally faster than the average growth in the Ecological Region 5. No fish > 24 inches TL were collected during the standard survey October 2003; however two eight-year-old largemouth bass in the 22- and 24-inch groups were collected during a LMBV survey July 2003. Their counterparts in Ecological Region 5 were only 20.8 inches TL at 8 years old. Relative weights varied by inch-group, but never lower than 80. Florida largemouth bass (FLMB) intergradation increased from 40.0 % FLMB alleles in 1998 to 57.0 % FLMB alleles in 2003. During the same period % FLMB (pure Florida) increased from 10.0% in 1998 to 17.0 % in 2003. Since 20 % FLMB alleles is the accepted minimum for FLMB influence in a population, we feel this current intergradation represents a significant accomplishment, especially since the last stocking of FLMB was in 2001. There was also an increase in intergradation from 2002 to 2003 and no FLMB were stocked during that time period. The high number of intergrades and pure FLMB recorded in 2000 and 2001 may have been influenced by collecting YOY in the fall, following a spring stocking. Except for an increase in directed angler effort from 1998 to 1999, directed angler effort and catch rate of largemouth bass declined during the three-year period from 1998 to 2000 according to annual creel survey statistics. Angler harvest was low all three years. There was evidence of non-compliance with the fish harvest regulation. An analysis of the spring quarter creel survey for 1998, 1999, 2001, and 2004 provided results similar to the annual analysis. Angler catch rate in the spring of 1998 was very near the same as for all seasons combined, directed effort was highest in the spring of 1999, thereafter, declining dramatically in the spring of 2004. Angler catch rate for largemouth bass was similar in 2001 and 2004. Again, harvest of largemouth bass was insignificant and non-compliance with the harvest regulation occurred in all years except 2004. The angler catch rate of largemouth bass in the spring of 1998 was 0.8/hour, 1/hour in spring of 1999, and 0.4/hour in spring of 2001 and 2004
• White crappie: Crappie is the second-most-sought-after species in this reservoir. Based on trap netting surveys, white crappie abundance continues to increase. The trap net catch rate of white crappie for 2003 was 8.6/net night, more than double the 4.0/net night collected in 2000, but slightly below the district average of 12.5/net night for 2003. The white crappie sample population included 29% legal-size fish (> 10 inches TL). Relative weights varied slightly by inch-group, but remained around 90. White crappie grew to 10 inches TL in 2 years and, in general, demonstrated a faster rate of growth than the average for Ecological Region 5 reservoirs. Annual creel survey statistics over a three-year period from 1998 to 2000 indicated a decline in directed angling effort for white crappie. Angler catch rate increased from 1998 to 1999, but sharply decreased from 1999 to 2000. Angler harvest rate of white crappie dropped to a record low in 2000. There was evidence of non-compliance with the fish harvest regulation in 1998 and 2000. We compared creel survey data from the spring quarters of 1998, 1999, 2001, and 2004. The highest directed angler effort and angler catch rate occurred in the spring of 2004. Angler harvest rate of white crappie was the second highest on record in the spring of 2004. Anglers harvested 0.5 crappie/hour.

Management Strategies

• Based on current information, the reservoir should be managed with existing fish harvest regulations.
• Concern for the apparent lack of largemouth bass in the slot, prompted an increase in electrofishing effort to include not only a standard fall electrofishing survey, but a spring electrofishing survey as well. Perhaps the standard fall electrofishing with a random sampling design is not effectively producing catches of big largemouth bass. It may be coincidental that electrofishing catches prior to random sampling contained more big bass. We plan to use non-random sample site selection to augment random sampling. Age and growth studies have shown largemouth bass in Ray Roberts Reservoir grow faster than their counterparts from other reservoirs in Ecological Region 5. The FLMB genotype is well represented in the population with FLMB alleles at 57% and pure FLMB at 17%. Intergradation persists despite the last FLMB stocking was in 2001.
• Concern for performance of the fishery as shown by recent creel surveys has prompted us to propose another annual creel survey to begin June 2004 and include the acquisition of anglers names and addresses who would consent to responding to and attitude and opinion mail-out survey. Furthermore, we propose to survey anglers who formerly fished Ray Roberts Reservoir, but failed to return in 2003 and 2004.
• Creel surveys showed harvest of illegal size fish. We plan to confirm evidence of noncompliance of fish harvest regulations with law enforcement personnel.
• Water quality problems may be contributing to declining primary productivity; hence fish production. We plan to research water quality history for Ray Roberts Reservoir with U.S. Geological Survey (USGS), Texas Commission on Environmental Quality (TCEQ), University of North Texas (UNT), and U.S. Army Corps of Engineers (USACOE) to identify latent water quality problems.
• Finally, we recommend updating the Ray Roberts Reservoir (Lake Ray Roberts) web page on the TPWD web site with appropriate information as needed.

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