LAKE TANEYCOMO 2012 ANNUAL LAKE REPORT. Shane Bush Fisheries Management Biologist Missouri Department of Conservation Southwest Region

Transcription

1 LAKE TANEYCOMO 12 ANNUAL LAKE REPORT Shane Bush Fisheries Management Biologist Missouri Department of Conservation Southwest Region March 1, 13

2 EXECUTIVE SUMMARY Lake Taneycomo was formed by the construction of Powersite Dam (Ozark Beach Dam) in 1913 and is Missouri's oldest hydroelectric reservoir. It is owned and operated by Empire District Electric Company (EDEC). The lake is riverine in nature, 22 miles in length, and encompasses 2,8 surface acres. Prior to 198, Lake Taneycomo supported one of Missouri's best warm-water fisheries. This changed in 198 when Table Rock Dam, located in the headwater of Lake Taneycomo, began discharging cold hypolimnetic water into Lake Taneycomo. The discharge of cold water changed Lake Taneycomo into a cold-water environment, providing good conditions for trout. Rainbow trout were first stocked into Lake Taneycomo in 198. Brown trout were first stocked in 198. Since that time more than 3 million rainbow and brown trout have been stocked. Lake Taneycomo is Missouri's largest and most popular trout fishery. It annually receives in excess of 14, fishing trips and anglers catch an estimated, trout annually. The Missouri Department of Conservation (MDC) coordinates fisheries management activities following the lake management plan that was updated in February. The 12 Lake Taneycomo trout electrofishing survey was conducted August, 12. With the cooperation of the Corps of Engineers and Southwest Power Administration, hydropower releases were terminated at hours and sampling began at 213 hours. Deputy Director Tom Draper, Fisheries Field Operations Chief Brian Canaday, and Jeff Williams, Arkansas Game and Fish Commission s Trout Program Supervisor, were among the crew of twenty that assisted with the sample. The seasoned and enthusiastic crew along with favorable weather conditions helped to make the sample a great success. Sampling was completed by 13 hours on August 16. Rainbow Trout Rainbow trout were captured at a rate of 248 fish per hour, well within the range of normal variation (Table 1, Figure 1). Size structure has decreased from previous years and could be attributed to the timing of the sample and smaller sized rainbow trout being stocked from Neosho National Fish Hatchery the week before. Body condition has improved from 11 with relative weights averaging 92 for all sizes (Table 2). Relative weights of rainbow trout decreased as the lengths of the fish increased. One potential reason for this decrease could be the length of time that the larger rainbow trout have been living in the lake foraging on natural food sources versus smaller, more recently stocked fish that have been heavily fed. Rainbow trout were collected at a rate of 278 fish per hour in the special regulation zone above Fall Creek (Table 3, Figure 2). In this same area, RSD 13 and RSD 16 were 8% and 9%, respectively. Rainbow trout were collected at a rate of 112 fish per hour below Fall Creek (Table 3, Figure 3). RSD 13 and RSD 16 values were 24% and 2%, respectively. It is likely that the majority of rainbow trout sampled, especially in the lower zones were related to recent stockings of smaller sized fish. Pending appropriate weather and dissolved oxygen conditions, trout sampling may be conducted toward the end of August or early September in 13 in an attempt to capture larger sized fish that typically move

3 up higher in the lake in the fall. Additionally, management staff will work with Shepherd of the Hills hatchery staff to minimize stockings of smaller Neosho fish in the week leading up to the sample. The special management zone has now been in place for 14 years in upper Lake Taneycomo. Since the special regulations were implemented in 1997, the rainbow trout population has increased -fold (Table 3). Size structure, in general, has greatly benefited as well. The percentage of stock-size rainbow trout at or exceeding 16 inches has increased above Fall Creek. Currently, RSD 16 of 16% exceeds the -% objective listed in the current management plan. Evidence of trophy rainbow trout being present was observed when two rainbow trout measuring 29 and 31 were caught by anglers in 12 (Figure 4). Body condition of rainbow trout has fluctuated over the past few years. The average relative weight of 88 in 11 was the same body condition that was observed during other recent high water years, such as 8 and 9. In 7 and there was reduced water flow through Table Rock Dam. Relative weights during these years were noticeably higher. Stable water flows through Table Rock Dam in 12 resulted in a slight improvement in relative weights from 11. An additional 66,99 rainbow trout were stocked into Lake Taneycomo in 12 (Table 4). Brown Trout The catch per unit effort (CPUE) of brown trout was 7 fish per hour, increasing nearly -fold from the 11 sample (Table, Figure ). Brown trout stocked in June 11 and January 12 comprised the majority of the catch. Due to the large numbers of two and three year old fish in the sample, size structure of brown trout was relatively low with RSD 13 and RSD 16 values measuring 1% and 7%, respectively. The recently stocked fish are doing very well and although RSD of 2% is among the lowest values on record, it should increase in future years as these fish continue to grow and contribute to the brown trout fishery. Body condition of brown trout has decreased slightly from 11, but remains above normal with average relative weight of 3 (Table 6). The increase in stocking of brown trout from, to, in the past two years has greatly contributed to the rebound of this fishery and should be continued in 13 as fish are available. Angler catch rates of larger sized brown trout will likely be low again in 13 due to the lack of intermediate sized fish (16 - ) in the population. However, catch rates of more recently stocked fish ( - 16 ) were reported to be good by anglers in 12 and catch rates of larger sized fish should continue to improve in the next couple of years as these fish continue to grow. An additional,238 brown trout averaging.3 inches were stocked into Lake Taneycomo in January 12 (Table 4). Due to an outbreak of disease in brown trout in the hatchery,, brown trout averaging 12. inches were stocked in November 12 as part of the 13 commitment. General Lake Activities

4 The low dissolved oxygen (DO) season in 12 was not as severe as it has been in the past few years. The vacuum breaker vents were blocked open at Table Rock Dam on July 6 and restrictions were placed on generation on October 19. Generation restrictions were lifted and vacuum breaker vents were closed on December 19. No adverse effects on the fish population were reported during the 12 low DO season. Zebra mussels have been known to be present in Lake Taneycomo since September 7. At that time, EDEC staff found several zebra mussels attached to a submerged log just upstream of the Powersite Dam. In 9, EDEC staff found another adult zebra mussel attached to a concrete block at Powersite Dam. No zebra mussels were observed in or 11. However, on March 1, 12, EDEC staff found an adult zebra mussel attached to the floating dock at Powersite Dam. It appears the spread of zebra mussels has been slow in Lake Taneycomo, perhaps due to the cold water temperatures. Signs educating boaters about the dangers of spreading zebra mussels are currently posted at all public launch ramps around the lake. In an effort to prevent the spread of Didymo geminata, a regulation banning the use of felt soled waders in Missouri s trout fishing waters went into effect on March 1, 12. This ban includes all of Lake Taneycomo and signs educating anglers about the ban have been posted lake wide. Results from the angler creel survey that began in February 8 and concluded in January were analyzed in 12. Overall, angler catch rates met the management objectives for fishing pressure and angler catch rates (Table 7). Additional results of the creel survey are summarized in the Lake Taneycomo 8-9 Angler Creel Survey Summary. Management Recommendations 1) Continue to collect trout population information annually and black bass and bluegill population information every three years resuming in 14 for regulation and monitoring purposes. 2) Continue to stock 7, rainbow trout and, brown trout annually. 3) Cooperate in ongoing efforts to monitor and enhance water quality and flow regimes. 4) Continue efforts through education of boaters and anglers to prevent the spread of zebra mussels, Didymo geminata, and other aquatic nuisance species from and to Lake Taneycomo. ) Review and comment on permit applications for boat dock construction and dredge and fill activities.

5 Table 1. Electrofishing capture rates (number/hour) and size structure indices of rainbow trout in August electrofishing samples, (RSD=Relative Stock Density, the percentage of stock-size fish exceeding a given length, either 13, 16 or inches). back to text Year Number/Hour RSD-13 RSD-16 RSD < < < < < < < < < < * <1 *For Zones 1, 2, and 4b only

6 Table 2. Relative weights of rainbow trout from Lake Taneycomo, back to text Year Relative Weight by Length Class (Inches) All Sizes <13. >13. >

7 Table 3. Electrofishing capture rates (number/hour) and size structure indices of rainbow trout in August electrofishing samples, taken above and below Fall Creek, (RSD=Relative Stock Density, the percentage of stock-size fish exceeding a given length, either 13 or 16 inches). back to text Year Number/Hour RSD-13 RSD-16 Above Fall Creek Regulation Area * Below Fall Creek Non-Regulation Area *For Zones 1 and 2 only

8 Table monthly stocking rates in Lake Taneycomo. back to text Month Rainbow Trout Brown Trout January 47,123,238 February 41,322 March,72 April 62,2 May 71,226 June 81,243 July 69,913 August 68,87 September 7,41 October 2,2 November 34,224, December 24,63 TOTAL 66,99 2,238

9 Table. Electrofishing capture rates (number/hour) and size structure indices of brown trout in August electrofishing samples, (RSD=Relative Stock Density, the percentage of stock-size fish exceeding a given length, either 13, 16 or inches). back to text Year Number/Hour RSD-13 RSD-16 RSD < < < * *For Zones 1, 2, and 4b only

10 Table 6. Relative weights of brown trout from Lake Taneycomo, back to text Year Relative Weight by Length Class (Inches) All Sizes <13. >13. >

11 Table 7. Estimated Fishing Hours and Catch Rates above and below Fall Creek, 8-9. Year Above Fall Creek Objective Estimated Trout Fishing Hours 8 96,6, 31,81 3, 9 1,128, 38,819 3, back to text Below Fall Creek Objective Lakewide Objective Rainbow Trout Catch Rate 8 2. > > Rainbow Trout Harvest Rate < Brown Trout Catch Rate Brown Trout Harvest Rate 8 <.1 <.1 <.1 9

12 Fish/Hr Fish/Hr Fish/Hr LAKE TANEYCOMO - 12 Effort = 4.3 hr. 248 Total RBT/hr. N = 73 RSD (13) = 6% RSD (16) = 9% RSD () = <1% LAKE TANEYCOMO - 11 Effort =.6 hr. 32 Total RBT/hr. N = 1689 RSD (13) = 9% RSD (16) = 16% RSD () = 1% LAKE TANEYCOMO - Effort = 4.3 hr. 24 Total RBT/hr. N = 6 RSD (13) = 7% RSD (16) = 18% RSD () = % Figure 1. Length frequencies for rainbow trout sampled in all zones -12. N = number of individuals captured back to text

13 Fish/Hr Fish/Hr Fish/Hr SPECIAL MANAGEMENT ZONE LAKE TANEYCOMO - 12 Effort = 3. hr. 278 Total RBT/hr. N = 983 RSD (13) = 8% RSD (16) = 9% RSD () = <1% SPECIAL MANAGEMENT ZONE LAKE TANEYCOMO - 11 Effort = 4.8 hr. 338 Total RBT/hr. N = 16 RSD (13) = 6% RSD (16) = 16% RSD () = 1% SPECIAL MANAGEMENT ZONE LAKE TANEYCOMO - Effort = 3. hr. 27 Total RBT/hr. N = 96 RSD (13) = 72% RSD (16) = 19% RSD () = % Figure 2. Length frequencies for rainbow trout sampled above Fall Creek -12. N = number of individuals captured back to text

14 Fish/Hr Fish/Hr Fish/Hr BELOW SPECIAL MANAGEMENT ZONE LAKE TANEYCOMO - 12 Effort =.8 hr. 112 Total RBT/hr. N = 9 RSD (13) = 24% RSD (16) = 2% BELOW SPECIAL MANAGEMENT ZONE LAKE TANEYCOMO - 11 Effort =.8 hr. 97 Total RBT/hr. N = 79 RSD (13) = 44% RSD (16) = % BELOW SPECIAL MANAGEMENT ZONE LAKE TANEYCOMO - Effort =.83 hr. 1 Total RBT/hr. N = RSD (13) = 43% RSD (16) = 6% Figure 3. Length frequencies for rainbow trout sampled below Fall Creek -12. N = number of individuals captured back to text

15 Figure and 31 rainbow trout caught in Lake Taneycomo in 12. back to text

16 Fish/Hr Fish/Hr Fish/Hr BROWN TROUT LENGTH FREQUENCY LAKE TANEYCOMO - 12 Effort = 4.3 hr. 7 Total BNT/hr. N = 463 RSD (13) = 1% RSD (16) = 7% RSD () = 2% BROWN TROUT LENGTH FREQUENCY LAKE TANEYCOMO - 11 Effort =.6 hr. 23 Total BNT/hr. N = 129 RSD (13) = 4% RSD (16) = 37% RSD () = % BROWN TROUT LENGTH FREQUENCY LAKE TANEYCOMO - Effort = 4.3 hr. 29 Total BNT/hr. N = 12 RSD (13) = 98% RSD (16) = 67% RSD () = 12% Figure. Length frequencies for brown trout sampled in all zones -12. N = number of individuals captured back to text