The Northwest Power and Conservation Council (Council or NPCC) asked the Independent Scientific Advisory Board (ISAB) to review the Upper Columbia United Tribes’ (UCUT) Fish Passage and Reintroduction Phase 1 Report: Investigations Upstream of Chief Joseph and Grand Coulee Dams (Reintroduction Report) and supporting documents. The Reintroduction Report was a broad analysis of key decision factors and potential outcomes to determine whether reintroduction of any of the historically present species of salmon and steelhead is feasible. The Council asked the ISAB to answer a set of questions about the strengths, data uncertainties, and limitations of each element of the UCUT’s report.
Brief answers to the Council’s questions
1. Strengths, data uncertainties, and limitations of each element of the UCUT’s report and critical gaps in the analyses
a. Donor stock and risk assessment
The Reintroduction Report prioritized donor stocks for reintroduction and concluded that summer/fall Chinook salmon is the preferred lineage for Chinook salmon in the blocked area. Kokanee from Lake Roosevelt and sockeye salmon from the Okanogan River are the highest ranked sources for sockeye. However, concerns about the abundance of kokanee and whether they would develop an anadromous life history led to a preference for Okanogan sockeye. The ISAB finds the process and recommendations for donor sources to be scientifically credible. Research, monitoring, and evaluation programs are needed to identify responses of donor sources and consequences of hatchery stocking, competition, predation, passage mortality, and other factors.
- Disease risks: Future assessments of disease risk should consider possible interactions between water quality, disease resistance, and other factors such as predator avoidance. The ISAB advocates development of a parentage-based tagging (PBT) program for all adults released in the blocked area to identify donors with the greatest disease resistance and to assess other factors that influence the success of reintroduction.
- Predation risks: The Reintroduction Report concluded that predation risk to juveniles of reintroduced salmon probably will be high overall but variable, depending on spatial and temporal overlap with potential predators. Numerous uncertainties about predators make more thorough evaluation critical in the next steps. Bioenergetic models could improve the understanding of the role of fish predation, especially by nonnative northern pike, on survival of introduced salmonids. Future effects of expanding populations of nonnative predators and a warming and changing climate also should be assessed. Non-fish predators – such as birds, mammals, including pinnipeds – should be considered in the assessment of risks to reintroduced salmon and included in the life cycle models.
b. Habitat assessments
The Reintroduction Report’s habitat assessments identified both current available habitat within the blocked area as well as habitat conditions above existing barriers that could be restored in the future. Data were provided in a format allowing consideration of reintroduction either solely within the United States or within the combined areas in the U.S. and Canada above Chief Joseph and Grand Coulee dams. The Report did not rely on future production from the Canadian portion of the basin but provided an assessment of Chinook salmon capacity in the Transboundary Reach.
The habitat assessments provided a reasonable set of hypotheses about the capacity of the habitat in the blocked area to support juvenile and adult salmonids, but the Fish and Wildlife Program will require additional information for future decisions. Overall, the estimates of potential adult capacities for both Chinook and sockeye salmon had wide ranges and included great uncertainty about habitat relationships and other factors, such as predation, fish passage, and survival in the lower Columbia River and ocean.
The ISAB commends the Reintroduction Report authors for considering the potential effects of climate change on reintroductions, which should be considered in future planning and implementation. Ocean survival of anadromous salmonids in the face of climate change is one of the most critical uncertainties facing reintroduction efforts but was not addressed in the Reintroduction Report. The discussion of climate change considered only the positive effects related to the lower thermal stress in the blocked area compared to warmer regions of the Columbia River. The Report did not consider climate-related factors that could negatively affect survival, such as interactions with other salmonid stocks, pathogens, lower river migration, or predators throughout the system.
c. Life-cycle modeling
The Life Cycle Model provides a framework for integrating information on potential habitat and reproductive capacity and for identifying data gaps. The model is simple to use and update. It provides a useful tool to inform decision making. However, the model is deterministic and incorporates little or no stochasticity, density dependence, or regime shifts in ocean productivity.
Outputs of the model are directly influenced by numerous uncertainties, which include a wide range of estimates of habitat availability and variation in adult spawner capacity. Use of the lower end of the distribution of estimated habitat and spawner capacity in applications of the LCM would be more conservative and precautionary. Sensitivity analysis should be expanded to evaluate the model and consequences of using estimates of the lower range of habitat and spawner capacity.
d. Adult and juvenile fish passage
The Reintroduction Report explored five possible options for adult passage and concluded that any of them could be used to pass adult salmon upstream over the two dams. The proposed interim adult passage approaches appear to be reasonable. Collecting and passing juvenile salmon downstream over Chief Joseph Dam and especially over Grand Coulee Dam represents a much greater challenge. At Grand Coulee Dam, fluctuations of reservoir levels would make passage for both life stages difficult. The passage assessment did not consider consequences of total dissolved gas supersaturated water, which may reduce survival and limit passage alternatives.
- Costs: The Reintroduction Report did not assess the costs of upstream and downstream passage options for salmon and steelhead. Specific donor stocks and passage systems have not been selected, thus only broad preliminary estimates of cost can be developed currently. More specific design elements and cost analysis will be possible after preliminary experiments and cultural releases of adult fish are completed. Future cost estimates would inform decisions about timing, combinations of actions that could be more effective than the individual actions on their own, and risks associated with the sequential, experimental nature of the reintroduction program. Incremental actions and numerous uncertainties make it important to incorporate cost analyses in the initial stages of the reintroduction effort.
2. In sum, how well do the report and its supporting documents address the biological and physical elements of Phase 1, as described in the Council’s Fish and Wildlife Program?
The 2014 Fish and Wildlife Program identifies several key steps in a phased approach to reintroduction of anadromous fish above Chief Joseph and Grand Coulee dams to mainstem reaches and tributaries in the United States. The Program specifically calls for 1) evaluation of information from passage studies at Grand Coulee and Chief Joseph dams and other blockages, 2) assessment of habitat availability, suitability and salmon survival potential above Grand Coulee, and 3) investigation of the scientific feasibility and possible cost of upstream and downstream passage options for salmon and steelhead. The Reintroduction Report addressed all these elements except for cost of passage options and provided a general proof of concept. The Report additionally evaluated donor stocks, disease risks, predation, and climate change, which are not specifically included in the reintroduction tasks identified in the Fish and Wildlife Program.
While it is reasonable to expect that reintroduction could be successful to some extent, there is great uncertainty about the numbers of adults that will return and the types of management that will be required to maintain them. A strategic plan for future steps and an adaptive management process will be needed to address these uncertainties. The ISAB encourages the UCUT and the Council to make decisions conservatively or with caution because of the very wide ranges of estimates of capacity and habitat availability. While the ISAB recommends careful development of future decisions and actions, it is clear the UCUT and their collaborators put a lot of thought and effort into this assessment and make the fundamental issues and management alternatives accessible to many stakeholders.
Numerous individuals and institutions assisted the ISAB with this report. Their help and participation are gratefully acknowledged. The ISAB especially appreciated the August 2019 site visit to the blocked Upper Columbia River Basin – Grand Coulee and Chief Joseph Dams, reservoirs, and tributaries – and the chance to hear from a wide range of tribal leaders; tribal, state, and federal scientists and fish managers; and Council members and staff.