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1994 Columbia River Basin Fish and Wildlife Program |
| Council document 94-55 | |
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< Section 10 table of contents
10.4 Sturgeon Mitigation
Sturgeon were once abundant in the Columbia River Basin. Population levels of sturgeon in some areas of the basin have declined, thereby raising concern about the long-term sustainability of the species. The Council believes that studies and evaluations should be undertaken and completed quickly, and on-the-ground projects identified and implemented as soon as possible to address the needs of this species. In addition, these studies should be coordinated to avoid redundant work and to increase the potential for learning.
10.4A Study and Evaluate Sturgeon Populations
Bonneville
10.4A.1 In consultation with the appropriate tribes and state agencies, fund the implementation of the sturgeon measures listed below.
10.4A.2 In consultation with the appropriate state agencies and tribes, fund research to determine the impact of development and operation of the hydropower system on sturgeon in the Columbia River Basin. These studies may include: 1) habitat requirements, 2) maintenance of genetic integrity, 3) stock assessment, 4) potential for artificial propagation, and 5) migration potential. Specific recommendations for the protection, mitigation and enhancement of sturgeon may be submitted to the Council upon completion of these studies.
10.4A.3 In consultation with the Umatilla Tribes and other appropriate state agencies and tribes, fund an evaluation, including a biological risk assessment (see measure 7.3B.1), of potential means of rebuilding sturgeon populations between Bonneville Dam and the mouth of the Snake River.
10.4A.4 In consultation with the Nez Perce Tribe, Idaho Department of Fish and Game, Oregon Department of Fish and Wildlife and other appropriate state agencies and tribes, fund an evaluation, including a biological risk assessment (see Measure 7.3B.1), of potential means of rebuilding sturgeon populations in the Snake River between Lower Granite and Hells Canyon dams.
10.4A.5 In consultation with the Nez Perce Tribe, Idaho Department of Fish and Game, Oregon Department of Fish and Wildlife, and other appropriate state agencies and tribes, fund an evaluation of a put-and-take consumptive sturgeon fishery in Hells Canyon and Oxbow Reservoirs. The study may include the production of test fish at the existing Nez Perce Tribe sturgeon rearing facility. Submit for Council review and approval prior to implementation.
10.4A.6 In consultation with the Spokane Tribe, the Colville Tribes and other appropriate state agencies and tribes, fund a three-year base-line assessment of sturgeon in Lake Roosevelt from Grand Coulee Dam to the international border, including the Spokane River arm on the Spokane Indian Reservation. Include estimates of: current population size, abundance of each age class, age/length frequency, recruitment rate, natural and fishing mortalities, distribution and migration patterns, harvest, life history, habitat usage, environmental factors affecting abundance and an assessment of the potential for artificial propagation. Submit recommendations from these studies to the Council.
10.4A.7 In consultation with the appropriate tribes and state agencies, fund an evaluation of the development and maintenance of operations and facilities to enhance white sturgeon production by supplementation for depressed populations in the impounded portions of the Columbia and Snake rivers. Submit for Council review and approval prior to implementation.
10.4A.8 In consultation with the appropriate tribes and state agencies, fund an evaluation of the development and maintenance of an experimental white sturgeon research facility for research on contaminants, reproduction and genetics of white sturgeon. Submit for Council review and approval prior to implementation.
10.4A.9 In consultation with the appropriate tribes and state agencies, fund white sturgeon population research in Lake Roosevelt, mid-Columbia and lower Snake river reservoirs.
Corps of Engineers
10.4A.10 In consultation with the appropriate tribes and state agencies, fund research regarding feasibility of additional sturgeon passage opportunities at The Dalles Dam by restoring existing fish lock facilities.
10.4B Kootenai River White Sturgeon
The Council recognizes that white sturgeon in the Kootenai River are a species of special cultural significance to the Kootenai Tribe of Idaho. Further, the Council notes that since the construction of Libby Dam in 1972, recruitment has been nil and the population has been in steady decline. In the 76 kilometer section of the Kootenai River between Bonners Ferry, Idaho, downstream to the Canadian Border, the population was estimated at 1,148 individuals in 1982 and 880 individuals in 1990. Absence of smaller-sized sturgeon and an increase in the overall size distribution of the population to larger-sized, older fish between 1982 and 1990 points to an absence in recruitment. The Council has been presented with testimony from the fishery managers that this decline in all probability is caused by two factors, altered flow regimes and load following, resulting from the operation of Libby Dam. The fishery managers believe that spring/summer flows in excess of 30,000 to 35,000 cubic feet per second at Bonners Ferry are needed to ensure adequate spawning and recruitment. Kootenai River white sturgeon were listed as an endangered species by the U.S. Fish and Wildlife Service in 1994. Degraded water quality, loss of sloughs and marshes (which may have formerly been potential fry habitat) due to diking, and reduced prey densities owing to Libby Dam trapping nutrients have also been suggested as contributing to the problem.
Since the Kootenai River white sturgeon population has had virtually no recruitment in the last 20 years, the Council has two recovery objectives. The first (short-term) is to act immediately to prevent further loss of genetic variability in the population. The second (long-term) is to restore natural reproduction and recruitment. These objectives will be accomplished in two ways. First, flow experiments will be conducted, in a manner consistent with the integrated rule curves for Libby Dam, in an attempt to identify the level of flows necessary for successful spawning and recruitment to occur. Second, to prevent additional losses of genetic variability to the population, owing to continued mortality with no replacement, genetically sound artificial propagation utilizing the Kootenai Tribal sturgeon culture station will be employed.
Until successful repeatable natural spawning of white sturgeon in the Kootenai River is shown to result in repeatable recruitment, recovery will include artificial production. Artificial production will follow guidelines set forth in the ?Kootenai River White Sturgeon Recovery Strategy? developed by the Kootenai Tribe of Idaho Fisheries Program, in collaboration with the Upper Columbia United Tribes Fisheries Research Center. The guidelines incorporate a breeding plan developed by Dr. Harold Kincaid, a U.S. Fish and Wildlife Service geneticist in a report to Bonneville published in 1993. Kincaid's plan protects the genetic integrity (by maintaining genetic variability) of the wild Kootenai River white sturgeon stock, utilizing conservation aquaculture, while simultaneously restoring the natural age structure to the population. The Council, by this action, approves both the Kootenai Tribe of Idaho/Upper Columbia United Tribes recovery plan and Kincaid breeding plan and incorporates them as part of this program. When the U.S. Fish and Wildlife Service develops a recovery plan for the Kootenai River white sturgeon, the Council will consult with the Kootenai Tribe and the Fish and Wildlife Service and other interested entities to determine if the recovery plan is consistent with the recovery strategy adopted here, and if not, to determine whether and how this recovery strategy should be revised.
The captive breeding program will use three to six females and an equal or greater number of males captured from the Kootenai River each spring. Fish will be spawned in pairs or in diallel mating designs to produce a minimum of five to six individual families that will be reared separately to maintain family identify. After hatching, approximately half the offspring shall be transferred to either Sandpoint or Cabinet Gorge hatchery in case catastrophic losses were to occur at one facility. Fish will be marked to identify family and year class before return to the river. Fish should be returned to the river as fall fingerlings to minimize potential adaptation to the hatchery environment. Initially, while tagging methods are tested to ensure positive identification after return to the river, it may be necessary to plant fish as spring yearlings. Total number of fish planted will be 5,000 to 7,000 if fall fingerlings or 1,000 to 1,200 if spring yearlings, with the number planted from each family equalized. Assuming annual survival rates of 20 percent during the first winter for fall fingerling plants and 50 percent for years one to three, and 85 percent for years four to 20 of all fish planted, the target numbers would yield 7.9 progeny per family or about four breeding pairs at age 20. Natural survival in the river environment during the 19+ years from planting to maturity would result in variability in genetic contribution of families to the next broodstock generation. Fish planted per family would be adjusted in future years when actual survival rate information is known. Broodfish will be tagged when captured to minimize multiple spawning of the same fish.
The annual number of progeny produced per family is determined by the number of successfully spawned females in a given year. If six distinct white sturgeon families are produced, the annual production goal of 1,200 age 1 fish will be met with 200 individuals per family. If 12 distinct families are produced, the annual production goal of 1,200 age 1 fish will be met with 100 fish per family. Producing an intermediate number of families (>6, <12) will meet the 1,200 fish target by adjustment of numbers of fish per family at age 1.
The following mating options are designed to preserve the population's remaining genetic variability, maximize the effective population number and begin rebuilding a natural age class structure.
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# Females |
# Males |
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2 |
8 |
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3 |
9 |
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4 |
4 |
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5 |
5 |
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6 |
6 |
After a fish, male or female, has produced one progeny family, it shall not be spawned again for a minimum of five years. After five years, a fish could be used to produce a second family only if no other unused fish are available for spawning. No fish will be used more than twice.
Biological objectives for endangered Kootenai River white sturgeon:
- Preserve existing gene pool and re-establish natural age structure of the population. To accomplish this goal, it will be necessary to have a minimum ?successful recruitment? by 100 families, with a family unit defined as one female crossed with one male, during the next 20 years (by 2015). ?Successful recruitment? is defined as enough fish to produce 4 to 10 sexually mature adults/family unit (average 7.9 adults/family unit) at 20 years of age. To reproduce natural age structure this will require that an average of five family units per year be spawned successfully, with approximately 200 age 1 individuals from each family recruited into the population each year for the next 20 years. This will result in a population of approximately 640 age 20 or older adults by 2035, which, when added to the number of individuals surviving from the wild population (223 estimated in 2035 based upon a current estimated 3.3 percent annual mortality) would stabilize the population at approximately the current population of 880 individuals older than age 20. Assuming that between 2015 and 2035, five families reproduce annually at the same rate, an additional 3,200 fish younger than age 20 would also be present. Of equal importance, the age structure of the population would be restored, thus allowing additional time to recover this stock. In essence, this objective boils down to producing 1,000 to 1,200 age 1 fish composed of five to six families of 20 fish each annually.
- Restore recruitment produced by naturally spawning adult sturgeon in the Kootenai River.
- At present, given the length of time anticipated for recovery to take place, no harvest or escapement targets have been established. However, it is a long range management objective of the Kootenai Tribe of Idaho to eventually restore this stock of sturgeon to a sufficient abundance and age distribution to allow for ceremonial, subsistence and recreational harvest by tribal members and recreational harvest by sport anglers.
Strategies to achieve biological objectives for Kootenai River white sturgeon:
- The Council's measures to restore endangered Kootenai River white sturgeon will undertake concurrent thrusts: 1) obtain higher water flows in the river to re-establish natural spawning, and 2) initiate a captive culture program to preserve existing genetic variation until natural spawning is restored.
- Utilize the Kootenai Tribal sturgeon culture station to augment recruitment until evidence is available to show that natural reproduction is yielding adequate recruits to sustain the genetic variability. Additionally, the captive culture program will utilize ?preservation stocking? techniques to minimize inbreeding, genetic bottlenecks and other detrimental effects that conventional supplementation programs have on wild fish populations. A parent stock of wild fish collected from the Kootenai River with an effective population size of 200 individuals (100 females and 100 males) or 100 families will be used to ensure genetic integrity. A constraint will be placed on the captive culture program to ensure that at least 70 percent of mature females in any given year are retained in the river and allowed to spawn naturally if river conditions permit. Available scientific evidence indicates that 22 to 42 females become mature each year, so using the more conservative lower value, up to six females could be captured annually and spawned to produce fish for the culture program. At a current 3.26 percent annual mortality rate, calculated from the difference between two population estimates made in 1982 (1,148 individuals) and 1990 (880 individuals), the number of females that could be used in future years would decline to five in five years, four in 10 years, and three in 15 years. The recruitment goal for each family in this program is enough fish to produce 4 to 10 adults at 20 years of age. This would require stocking approximately 5,000 to 7,000 total age 0 fish or 1,000 to 1,200 total age 1 fish with equal numbers stocked from each family.
- The captive breeding program will use three to six females and an equal or greater number of males captured from the Kootenai River each spring. Fish will be spawned in pairs or in diallel mating designs to produce individual families that will be reared separately to maintain family identity. Fish will be marked to identify family and year class before return to the river. Fish should be returned to the river as fall fingerlings to minimize potential adaptation to the hatchery environment. Initially, while tagging methods are tested to ensure positive identification after return to the river, it may be necessary to plant fish as spring yearlings. Total number of fish planted will be 5,000 to 7,000 if fall fingerlings or 1,000 to 1,200 if spring yearlings, with equal numbers planted from each family. Assuming annual survival rates of 20 percent during the first winter for fall fingerling plants and 50 percent for years one to three, and 85 percent for years four-20 of all fish planted, the target numbers would yield 7.9 progeny per family or about four breeding pairs at age 20. Natural survival in the river environment during the 19+ years from planting to maturity would result in variability in genetic contribution of families to the next broodstock generation. Broodfish will be tagged after spawning to minimize multiple spawnings of the same fish.
- Operate Libby reservoir according to the Integrated Rule Curve guidelines in an attempt to provide for natural spawning and recruitment within the Kootenai River. Implementation and duration of discharge will be consistent with Section 10.3B.1 and 10.3B.2.
Measures to achieve biological objectives for Kootenai River white sturgeon:
Kootenai Tribe of Idaho
10.4B.1 Operate and maintain a low-capital sturgeon hatchery on the Kootenai Indian Reservation. With Bonneville, explore alternative ways to make effective use of the hatchery facility year-round.
10.4B.2 Survey the Kootenai River downstream from Bonners Ferry, Idaho, to the Canadian border to: 1) evaluate the effectiveness of the hatchery, and 2) assess the impact of water-level fluctuations caused by Libby Dam on hatchery operations for outplanting of sturgeon in the Idaho portion of the Kootenai River.
Bonneville and Corps of Engineers
10.4B.3 Release water from Libby Dam to augment river discharge during the historic white sturgeon spawning period (May-July) to accomplish flow experiments and attempt to encourage natural spawning and recruitment. The purpose of these experiments shall be to identify the minimum flows required to achieve natural spawning and recruitment of year classes. Implementation and duration of discharge will be consistent with Section 10.3B.1 and 10.3B.2.
10.4B.4 Follow the accompanying operating guidelines at Libby Dam when augmenting discharges:
- Variation in discharge (?load factoring? or ?load following?) should be eliminated or minimized during wettest 66 percent of water years. Load factoring is permissible during the driest 33 percent of water years, but efforts to minimize load factoring every year are strongly encouraged.
- A minimum stream flow of 12,000 cubic feet per second should be maintained from May 1 through August 25 at Bonners Ferry during the 66 percent wettest years to eliminate stranding of larvae and juvenile fishes, and to reduce the chances of the river reaching lethally high temperatures during the white sturgeon egg incubation and larval development periods.
- Augmented discharge in the 66 percent wettest years should occur in such a way as to maintain 8? to 14? centigrade water temperature at Bonners Ferry from the first to the 45th day of augmented discharge.
- Ramping up and down to and from augmented discharge levels should occur over at least a 96-hour period.
- During the 66 percent wettest years, water temperature should be 18? centigrade between the 45th day of augmented discharge and August 25 (during the 12,000 cubic feet per second minimum discharge period) to maximize survival of white sturgeon eggs and larvae.
- Experimental discharges should be provided during average water years (33-66 percent wettest years) to test how incremental discharge increases affect natural spawning and recruitment of white sturgeon in the Kootenai River. The emphasis during such years should be on providing different discharge regimes to determine if natural reproduction and recruitment can be achieved with moderate discharge.
- Natural spawning experiments will also be conducted to determine if moderate discharge regimes, shaped differently than current discharge patterns, can satisfy the recovery objective of reestablishing natural spawning and recruitment of white sturgeon in the Kootenai River. In addition to shaping augmented discharge, effects of increased discharge duration will be evaluated. The aim of these natural spawning experiments is to use adaptive river management to test hypotheses concerning natural spawning requirements of white sturgeon in the Kootenai River.
- Augmented discharge will not occur during below average water (<33 percent wettest years) to better allow reservoir refill, thereby enabling greater water availability for natural spawning tests in subsequent years. Not releasing water through Libby Dam during below average water years will also reduce negative effects on resident fisheries and recreation in Lake Koocanusa currently caused by low reservoir surface elevations.
- Discharge augmentation in above average water years will be automatically implemented once the predetermined adequate amount of water is available. The Corps of Engineers should provide reports including runoff forecast and water availability data to all involved management agencies (Kootenai Tribe of Idaho, Idaho Department of Fish and Game, Montana Department of Fish, Wildlife and Parks, U.S. Fish and Wildlife Service, Bonneville, Pacific Northwest Utilities Conference Committee). Annual implementation of augmented discharge will be based on run-off forecasts and water availability data provided by these reports made available and updated from January to March of every year.
- By March 15, the Corps of Engineers shall provide an annual report of runoff and water availability, which will determine the targeted Kootenai River Water Budget for white sturgeon, to the Council and to appropriate fisheries management agencies (Kootenai Tribe of Idaho, Idaho Department of Fish and Game, Montana Department of Fish, Wildlife and Parks, U.S. Fish and Wildlife Service). These four agencies (water budget team) will consult with Bonneville and the Corps of Engineers to develop an annual implementation plan that shapes the flows for conducting adaptive management experiments. The report will be submitted to the Council by the water budget team annually by April 1. This report will describe the dates and times, ramping rates, shapes of flows and temperature guidelines for the sturgeon spawning experiment to be conducted that year.
- The range of augmented discharge during average water years (15,000-25,000 cubic feet per second) is designed to investigate white sturgeon spawning over a wide range of discharge regimes.
- The furthest downriver suspected spawning habitat for white sturgeon exists near Shorty's Island, located downstream from Bonners Ferry. Due to braided channel morphology in this area of the river, an increase of discharges from 22,000 to 23,000 cubic feet per second provides a nearly five-fold increase in predicted spawning habitat. Therefore, during average water years, effort should be made when possible to provide discharge between 23,000 and 25,000 cubic feet per second at Bonners Ferry. However, effects of discharge on spawning should also be evaluated at discharges ranging from 15,000 to 22,000 cubic feet per second at Bonners Ferry in average water years.
Kootenai Tribe of Idaho, Idaho Department of Fish and Game, and Montana Department of Fish, Wildlife and Parks
10.4B.5 As part of the Kootenai sturgeon recovery strategy (see measure 10.4B.4 above):
- The Kootenai Tribe of Idaho is to operate the Kootenai Tribal sturgeon hatchery and develop propagation methods that ensure healthy sturgeon are outplanted into the Kootenai River commencing in 1995. Also, mark all hatchery-released fish to distinguish from naturally produced fish. The Idaho Department of Fish and Game is to rear white sturgeon at Sandpoint or Cabinet Gorge hatcheries commencing in 1995.
- The Kootenai Tribe of Idaho, Idaho Department of Fish and Game and Montana Department of Fish, Wildlife and Parks will participate on the water budget team, commencing in 1996.
- The Kootenai Tribe of Idaho, Idaho Department of Fish and Game and Montana Department of Fish, Wildlife and Parks are to conduct monitoring and evaluation to assess the effectiveness of these measures, and investigate critical uncertainties about other factors that may contribute to reduced sturgeon recruitment, commencing in 1995. The monitoring and evaluation program shall include: 1) an assessment of spawning success and natural recruitment to the juvenile population under high discharge in high runoff years, experimental discharges in moderate runoff years and no flow augmentation in below average runoff years; 2) an assessment of hatchery releases; 3) an assessment of exactly how and why low Kootenai River discharges affect sturgeon recruitment; and 4) an assessment of factors other than discharge that may be contributing to the lack of Kootenai River white sturgeon spawning success and recruitment. Such factors potentially include pollutants, limited food resources (at various life history stages), predation, combination of altered thermal regimes and limited food availability that could cause poor winter survival of young-of-the-year sturgeon, and lack of habitat for fry, juvenile or subadult life history stages. In particular, data shall be collected to develop bioenergetics models that assess the impact of predatory fish consumption of sturgeon eggs and larvae to recruitment of sturgeon year classes. As part of this study, the impact of low versus high discharges on the intensity and rates of predation on sturgeon eggs and larvae shall be investigated. The project will determine the feasibility of utilizing predator management as a tool to improve sturgeon recruitment. This investigation shall also focus on assessing larval and overwinter survival of age 0 sturgeon as it relates to the current levels of primary and secondary production in the river and Kootenay Lake.