Lake Roosevelt Fisheries Evaluation Program, Assessment of the Lake Roosevelt Walleye Population 1998 Annual Report PDF Download
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Languages : en
Pages : 67
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A walleye mark-recapture experiment was initiated on Lake Roosevelt in 1997, with the primary objective of estimating the size of the walleye population. The project was continued in 1998 with a revised sampling regime. The primary goals during 1998 were to estimate the size of the walleye population in Lake Roosevelt, estimate the size of the spawning run in the Spokane River Arm, and describe the age structure of the population for use in managing the population and developing a kokanee bioenergetics model. Secondary objectives included: determining walleye movements, back-calculating growth rates, estimating mortality rates, determining walleye condition, and estimating walleye young-of-the-year (YOY) production in the Spokane River Arm. All walleye, ≥ 150 mm TL, were marked with individually numbered Floy{reg_sign} tags, during five passes through the reservoir. The passes occurred between April 1st and September 16th, 1998. The most unbiased estimate of walleye abundance in Lake Roosevelt, 186,482 (40,113 ≤ N ≤ 943,213), was obtained using the Mtb model of the CAPTURE program. The most unbiased estimate of the size of the walleye spawning run in the Spokane River Arm, 27,345 (1,535 ≤ N ≤ 57,519), was calculated using the Jolly-Seber model. The abundance estimates appeared reasonable, but they had wide 95 % confidence intervals. Wide confidence intervals were attributed to low capture probabilities. Coefficient of variation (CV) values for both estimates indicated that they were not acceptable for general management, not to mention research. Despite the CV value, we felt that the reservoir estimate was reasonable and that it was the best possible, without a large increase in effort and money. The spawning run estimate could have been improved by a small increase in effort. Ages of walleye in Lake Roosevelt ranged from 0 to 13 years. Growth, mortality, and condition were all average when compared to other walleye producing waters. We recommended that there be no changes in the management of the Lake Roosevelt walleye population and that three separate values of walleye abundance be used in the calculation of the kokanee bioenergetics model.
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Languages : en
Pages : 67
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A walleye mark-recapture experiment was initiated on Lake Roosevelt in 1997, with the primary objective of estimating the size of the walleye population. The project was continued in 1998 with a revised sampling regime. The primary goals during 1998 were to estimate the size of the walleye population in Lake Roosevelt, estimate the size of the spawning run in the Spokane River Arm, and describe the age structure of the population for use in managing the population and developing a kokanee bioenergetics model. Secondary objectives included: determining walleye movements, back-calculating growth rates, estimating mortality rates, determining walleye condition, and estimating walleye young-of-the-year (YOY) production in the Spokane River Arm. All walleye, ≥ 150 mm TL, were marked with individually numbered Floy{reg_sign} tags, during five passes through the reservoir. The passes occurred between April 1st and September 16th, 1998. The most unbiased estimate of walleye abundance in Lake Roosevelt, 186,482 (40,113 ≤ N ≤ 943,213), was obtained using the Mtb model of the CAPTURE program. The most unbiased estimate of the size of the walleye spawning run in the Spokane River Arm, 27,345 (1,535 ≤ N ≤ 57,519), was calculated using the Jolly-Seber model. The abundance estimates appeared reasonable, but they had wide 95 % confidence intervals. Wide confidence intervals were attributed to low capture probabilities. Coefficient of variation (CV) values for both estimates indicated that they were not acceptable for general management, not to mention research. Despite the CV value, we felt that the reservoir estimate was reasonable and that it was the best possible, without a large increase in effort and money. The spawning run estimate could have been improved by a small increase in effort. Ages of walleye in Lake Roosevelt ranged from 0 to 13 years. Growth, mortality, and condition were all average when compared to other walleye producing waters. We recommended that there be no changes in the management of the Lake Roosevelt walleye population and that three separate values of walleye abundance be used in the calculation of the kokanee bioenergetics model.
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Languages : en
Pages : 70
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A walleye mark-recapture study was conducted on Lake Roosevelt between 1997 and 1999. The primary objective of the study was to describe the status and biological characteristics of the walleye population in Lake Roosevelt by determining its abundance, movement patterns, age structure, growth, condition, and mortality. The abundance estimates were also to be used to estimate the consumptive impact of walleye on stocked kokanee and rainbow trout. Walleye were collected by electrofishing and angling. Each walleye was tagged with an individually numbered Floy tag. The Jolly-Seber model was used to estimate the size of the walleye population in 1999, using each year of the study as a mark-recapture occasion. Mark-recapture data collected in 1998 was re-analyzed in 1999 with the data pooled in various combinations, using closed and open population models, in an attempt to provide an estimate of walleye abundance that was unbiased, accurate, and more precise. Minimum distances traveled between mark and recapture location by tagged walleye were determined from tag returns. Over the three study years, a total of 12,343 walleye ≥ 150 mm TL were collected by Eastern Washington University (EWU), Spokane Tribe of Indians, and Washington Department of Fish and Wildlife, and of those, 10,770 were tagged and released. Of the 10,770 walleye marked and released, 775 were recaptured and returned to EWU. The 1999 abundance estimate (± standard error) for walleye ≥ 150 mm TL was 129,183 (± 45,578) and the estimated abundance (± standard error) of walleye ≥ 200 mm TL was 101,508 (± 35,603). A total of 38 population estimates were calculated for 1998. The estimates of the abundance of walleye ≥ 150 mm TL in Lake Roosevelt ranged from 84,335 to 180,568 fish. Estimates of the size of the walleye population ≥ 200 mm TL ranged from 14,971 to 173,702. The 1999 estimate, which used each study year as a mark-recapture occasion, was biased due to unequal capture probabilities. If biases were eliminated, the annual sampling strategy may be the most cost-effective. Of the reanalyzed 1998 estimates, the Schnabel corrected for tag loss and recruitment and the Jolly-Seber estimate, both calculated with the 200 mm minimum length, were recommended for modeling walleye consumption. Minimum distances traveled between mark and recapture location by tagged walleye marked on the spawning run ranged from 0 to 245 km over a range of 11 to 486 days. Minimum distances traveled between mark and recapture location by tagged walleye marked during the summer/fall ranged from 0 to 217 km over a range of 8 to 788 days. Walleye exhibited seasonal movement trends that included a migration to the spawning area in the upper Spokane River Arm in the spring, with peak spawning occurring in April and May, and a migration following spawning to summer habitats. Once at the summer habitat, walleye appeared to establish summer home ranges (SHR). Walleye collected in Lake Roosevelt in 1999 ranged in age from 0 to 8. Mean instantaneous and mean annual mortality were estimated at 0.62% and 46%. Mean condition factor (K{sub TL}) of the 343 walleye measured and weighed in 1999 was 0.83 (SD = 0.13). Walleye mortality rates appeared to be relatively stable. Mortality and growth were average when compared to other walleye producing waters. Walleye condition was low when compared to condition factors in 1980-83, 1988, 1989, and 1990. The K{sub TL}'s of walleye from Lake Roosevelt were slightly below average when compared to other walleye populations.
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Languages : en
Pages : 96
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The Lake Roosevelt Fisheries Evaluation Program is the result of a merger between two projects, the Lake Roosevelt Monitoring Program (BPA No. 8806300) and the Lake Roosevelt Data Collection Project (BPA No. 9404300). These projects were merged in 1996 to continue work historically completed under the separate projects, and is now referred to as the Lake Roosevelt Fisheries Evaluation Program. Creel and angler surveys estimated that anglers made 196,775 trips to Lake Roosevelt during 1998, with an economic value of $8.0 million dollars, based on the Consumer Price Index (CPI). In 1998 it was estimated that 9,980 kokanee salmon, 226,809 rainbow trout, 119,346 walleye, and over 14,000 smallmouth bass and other species were harvested. Creel data indicates that hatchery reared rainbow trout contribute substantially to the Lake Roosevelt fishery. The contribution of kokanee salmon to the creel has not met the expectations of fishery managers to date, and is limited by entrainment from the reservoir, predation, and possible fish culture obstacles. The 1998 Lake Roosevelt Fisheries Creel and Population Analysis Annual Report includes analyses of the relative abundance of fish species, and reservoir habitat relationships (1990-1998). Fisheries surveys (1990-1998) indicate that walleye and burbot populations appear to be increasing, while yellow perch, a preferred walleye prey species, and other prey species are decreasing in abundance. The long term decreasing abundance of yellow perch and other prey species are suspected to be the result of the lack of suitable multiple reservoir elevation spawning and rearing refugia for spring spawning reservoir prey species, resulting from seasonal spring-early summer reservoir elevation manipulations, and walleye predation. Reservoir water management is both directly, and indirectly influencing the success of mitigation hatchery production of kokanee salmon and rainbow trout. Tag return data suggested excessive entrainment occurred in 1997, with 97 percent of tag recoveries from rainbow trout coming from below Grand Coulee Dam. High water years appear to have substantial entrainment impacts on salmonids. The 1998 salmonid harvest has improved from the previous two years, due to the relatively water friendly year of 1998, from the harvest observed in the 1996-1997 high water years, which were particularly detrimental to the reservoir salmonid fisheries. Impacts from those water years are still evident in the reservoir fish populations. Analysis of historical relative species abundance, tagging data and hydroacoustical studies, indicate that hydro-operations have a substantial influence on the annual standing crop of reservoir salmonid populations due to entrainment losses, and limited prey species recruitment, due to reservoir elevation level fluctuation, and corresponding reproductive success.
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Pelagic fishes, such as kokanee and rainbow trout, provide an important fishery in Lake Roosevelt; however, spawner returns and creel results have been below management goals in recent years. Our objective was to identify factors that potentially limit pelagic fish production in Lake Roosevelt including entrainment, food limitation, piscivory, and other abiotic factors. We estimated the ratio of total fish entrained through Grand Coulee Dam to the pelagic fish abundance for September and October, 1998. If the majority of these fish were pelagic species, then entrainment averaged 10-13% of pelagic fish abundance each month. This rate of entrainment could impose considerable losses to pelagic fish populations on an annual basis. Therefore, estimates of species composition of entrained fish will be important in upcoming years to estimate the proportion of stocked pelagic fish lost through the dam. Food was not limiting for kokanee or rainbow trout populations since growth rates were high and large zooplankton were present in the reservoir. Estimates of survival for kokanee were low (0.01 annual) and unknown for rainbow trout. We estimated that the 1997 standing stock biomass of large (1.1 mm) Daphnia could have supported 0.08 annual survival by kokanee and rainbow trout before fish consumption would have exceeded available biomass during late winter and early spring. Therefore, if recruitment goals are met in the future there may be a bottleneck in food supply for pelagic planktivores. Walleye and northern pikeminnow were the primary piscivores of salmonids in 1996 and 1997. Predation on salmonid prey was rare for rainbow trout and not detected for burbot or smallmouth bass. Northern pikeminnow had the greatest individual potential as a salmonid predator due to their high consumptive demand; however, their overall impact was limited because of their low relative abundance. We modeled the predation impact of 273,524 walleye in 1996, and 39,075 northern pikeminnow in 1997 because diet data revealed predation on salmonids during these years. We could not determine the absolute impact of piscivores on each salmonid species because identification of fish prey was limited to families. Our estimate of salmonid consumption by walleye in 1996 and northern pikeminnow in 1997 shows that losses of stocked kokanee and rainbow trout could be substantial (up to 73% of kokanee) if piscivores were concentrating on one salmonid species, but were most likely lower, assuming predation was spread among kokanee, rainbow trout, and whitefish. Dissolved oxygen was never limiting for kokanee or rainbow trout, but temperatures were up to 6 EC above the growth optimum for kokanee from July to September in the upper 33 meters of water. Critical data needed for a more complete analysis in the future include species composition of entrainment estimates, entrainment estimates expanded to include unmonitored turbines, seasonal growth of planktivorous salmonids, species composition of salmonid prey, piscivore diet during hatchery releases of salmonids, and collection of temperature and dissolved oxygen data throughout all depths of the reservoir during warm summer months.
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Languages : en
Pages : 44
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Walleye (Stizostedion vitreum) have been marked with floy tags in Lake Roosevelt since 1997 to estimate abundance, distribution and movement trends. In 2000, walleye were collected and marked during the spawning run in the Spokane River through electrofishing and angling to supplement movement and growth data collected in previous years. Walleye were also collected and marked during the 2000 and 2001 Kettle Falls Governor's Cup Walleye Tournaments. Seventy-six tag returns were recovered in 2000 and twenty-three in 2001. Walleye migrated into the Spokane River to spawn in mid April and early May. The majority of marked walleye were recovered within 25 km of their original marking location, with a few traveling long distances between recovery locations. Data also verified earlier results that walleye establish summer home ranges. Some walleye remained in the Spokane River, while others moved downstream, or upstream after entering the mainstem of Lake Roosevelt. Those moving upstream moved as far north as Keenlyside Dam in British Columbia (245 km). Growth data indicated similar trends exhibited in the past. Walleye growth and mortality rates were consistent with other walleye producing waters. Walleye condition was slightly below average when compared to other systems.
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Languages : en
Pages : 95
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The Lake Roosevelt Fisheries Evaluation Program is the result of a merger between two projects, the Lake Roosevelt Monitoring Program (BPA No. 8806300) and the Lake Roosevelt Data Collection Project (BPA No. 9404300). These projects were merged in 1996 to continue work historically completed under the separate projects, and is now referred to as the Lake Roosevelt Fisheries Evaluation Program. The 1998 Annual Report, Part B. Limnology, Primary Production, and Zooplankton in Lake Roosevelt, Washington examined the limnology, primary production, and zooplankton at eleven locations throughout the reservoir. The 1998 research protocol required a continuation of the more complete examination of limnological parameters in Lake Roosevelt that began in 1997. Phytoplankton and periphyton speciation, phytoplankton and periphyton chlorophyll a analysis, complete zooplankton biomass analysis by taxonomic group, and an increased number of limnologic parameters (TDG, TDS, etc.) were examined and compared with 1997 results. Total dissolved gas levels were greatly reduced in 1998, compared with 1997, likely resulting from the relatively normal water year experienced in 1998. Mean water temperatures were similar to what was observed in past years, with a maximum of 22.7 C and a minimum of 2.6 C. Oxygen concentrations were also relatively normal, with a maximum of 16.6 mg/L, and a minimum of 0.9 mg/L. Phytoplankton in Lake Roosevelt was primarily composed of microplankton (29.6%), Cryptophyceae (21.7%), and Bacillriophyceae (17.0 %). Mean total phytoplankton chlorophyll a maximum concentration occurred in May (3.53 mg/m3), and the minimum in January (0.39 mg/m3). Phytoplankton chlorophyll a concentrations appear to be influenced by hydro-operations and temperature. Trophic status as indicated by phytoplankton chlorophyll a concentrations place Lake Roosevelt in the oligomesotrophic range. Periphyton colonization rates and biovolume were significantly greater at a depth of 1.5 m (5 ft) when compared with a 4.6 m (15 ft) depth, and during the shorter incubation periods (two and four weeks). Mean zooplankton densities were greatest for Copepoda (88 %), then Daphnia spp. (10%) and other Cladocera (2.1%), while the zooplankton biomass assessment indicated Daphnia spp. had the greatest biomass (53.6%), then Copepoda (44.0%) and other Cladocera (2.5%). Mean overall zooplankton densities were the lowest observed since 1991. The cause was unclear, but may have been an artifact of human error. It seems unlikely that hydro-operations played a significant part in the reduction of zooplankton in light of the relatively friendly water year of 1998.
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Languages : en
Pages : 120
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Hatchery supplementation of kokanee Oncorhynchus nerka and rainbow trout O. mykiss has been the primary mitigation provided by Bonneville Power Administration for loss of anadromous fish to the waters above Grand Coulee Dam (GCD). The hatchery program for rainbow trout has consistently met management goals and provided a substantial contribution to the fishery; however, spawner returns and creel survey results for kokanee have been below management goals. Our objective was to identify factors that limit limnetic fish production in Lake Roosevelt by evaluating abiotic conditions, food limitations, piscivory, and entrainment. Dissolved oxygen concentration was adequate throughout most of the year; however, levels dropped to near 6 mg/L in late July. For kokanee, warm water temperatures during mid-late summer limited their nocturnal distribution to 80-100 m in the lower section of the reservoir. Kokanee spawner length was consistently several centimeters longer than in other Pacific Northwest systems, and the relative weights of rainbow trout and large kokanee were comparable to national averages. Large bodied daphnia (> 1.7 mm) were present in the zooplankton community during all seasons indicating that top down effects were not limiting secondary productivity. Walleye Stizostedion vitreum were the primary piscivore of salmonids in 1998 and 1999. Burbot Lota lota smallmouth bass Micropterus dolomieui, and northern pikeminnow Ptychocheilus oregonensis preyed on salmonids to a lesser degree. Age 3 and 4 walleye were responsible for the majority (65%) of the total walleye consumption of salmonids. Bioenergetics modeling indicated that reservoir wide consumption by walleye could account for a 31-39% loss of stocked kokanee but only 6-12% of rainbow trout. Size at release was the primary reason for differential mortality rates due to predation. Entrainment ranged from 2% to 16% of the monthly abundance estimates of limnetic fish, and could account for 30% of total mortality of limnetic fishes, depending on the contribution of littoral zone fishes. Inflow to GCD forebay showed the strongest negative relationship with entrainment whereas reservoir elevation and fish vertical distribution had no direct relationship with entrainment. Our results indicate that kokanee and rainbow trout in Lake Roosevelt were limited by top down impacts including predation and entrainment, whereas bottom up effects and abiotic conditions were not limiting.
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Category : Science
Languages : en
Pages : 468
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Languages : en
Pages : 226
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The Grand Coulee Dam was constructed in 1939 without a fish ladder, which eliminated steelhead (Onchorhynchus mykiss), chinook salmon (O. twshwastica), coho salmon (O. kisutch) and sockeye salmon (O. nerka) from returning to approximately 1,835 km (1,140 miles) of natal streams and tributaries found in the upper Columbia River Drainage in the United States and Canada. The Pacific Northwest Electric Power Planning and Conservation Act of 1980 gave the Bonneville Power Administration (BPA), the authority and responsibility to use its legal and financial resources, 'to protect, mitigate, and enhance fish and wildlife to the extent affected by the development and operation of any hydroelectric project of the Columbia River and its tributaries. This is to be done in a manner consistent with the program adopted by the Northwest Power Planning Council (NWPPC), and the purposes of the Act' (NWPPC, 1987). With the phrase 'protect, mitigate and enhance', Congress signaled its intent that the NWPPC's fish and wildlife program should do more than avoid future hydroelectric damage to the basin's fish and wildlife. The program must also counter past damage, work toward rebuilding those fish and wildlife populations that have been harmed by the hydropower system, protect the Columbia Basin's fish and wildlife resources, and mitigate for harm caused by decades of hydroelectric development and operations. By law, this program is limited to measures that deal with impacts created by the development, operation and management of hydroelectric facilities on the Columbia River and its tributaries. However, off-site enhancement projects are used to address the effects of the hydropower system on fish and wildlife (NWPPC 1987). Resident game fish populations have been established in Franklin D. Roosevelt Lake, the reservoir behind Grand Coulee Dam, since the extirpation of anadromous fish species. The resident game fish populations are now responsible for attracting a large percentage of the recreational visits to the region. An increase in popularity has placed Lake Roosevelt fifth amongst the most visited State and Federal parks in Washington. Increased use of the reservoir prompted amplified efforts to enhance the Native American subsistence fishery and the resident sport fishery in 1984 with hatchery supplementation of rainbow trout (O. mykiss) and kokanee salmon (O. nerka). This was followed by the formation of the Spokane Tribal Lake Roosevelt Monitoring Project (LRMP) in 1988 and later by formation of the Lake Roosevelt Data Collection Project in 1991. The Lake Roosevelt Data Collection Project began in July 1991 as part of the BPA, Bureau of Reclamation, and U.S. Army Corps of Engineers System Operation Review process. This process sought to develop an operational scenario for the federal Columbia River hydropower system to maximize the in-reservoir fisheries with minimal impacts to all other stakeholders in the management of the Columbia River. The Lake Roosevelt Monitoring/Data Collection Program (LRMP) is the result of a merger between the Lake Roosevelt Monitoring Program (BPA No. 8806300) and the Lake Roosevelt Data Collection Project (BPA No. 9404300). These projects were merged in 1996 forming the Lake Roosevelt Monitoring Program (LRMP), which continues the work historically completed under the separate projects. The LRMP has two main goals. The first is to develop a biological model for Lake Roosevelt that will predict in-reservoir biological responses to a range of water management operational scenarios, and to develop fisheries and reservoir management strategies accordingly. The model will allow identification of lake operations that minimize impacts on lake biota while addressing the needs of other interests (e.g. flood control, hydropower generation, irrigation, and downstream resident and anadromous fisheries). Major components of the model will include: (1) quantification of entrainment and other impacts to phytoplankton, zooplankton and fish caused by reservoir drawdowns and low water retention times; (2) quantification of seasonal distributions, standing crop, and habitat use of fish food organisms; (3) examination of variations in fish growth and abundance in relation to reservoir operations, prey abundance and predator/prey relationships; and (4) quantification of habitat alterations due to hydrooperations. The second goal of the LRMP is to evaluate the impacts of hatchery kokanee salmon and rainbow trout on the ecosystem and to determine stocking strategies that maximize angler harvest and return of adult kokanee salmon to egg collection facilities. Major tasks of the hatchery evaluation portion of the project include conducting a year round reservoir wide creel survey, sampling the fishery during spring, summer and fall via electro-fishing and gillnet surveys, and collecting information on diet, growth, and age composition of various fish species in Lake Roosevelt.
Author: Jason G. McLellan
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Category : Franklin D. Roosevelt Lake (Wash.)
Languages : en
Pages : 68
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