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Basin Salmon Science Panel says Smolt-to-Adult Return Objectives Should be Re-Evaluated by Staff Columbia Basin Bulletin, November 1, 2013

A new Independent Scientific Advisory Board review of the Fish Passage Center's long-running Comparative Survival Study has shown trends in the survival of salmon and steelhead that navigate the Columbia-Snake river hydro system.

Now the researchers need to look closer at what causes the survival differentials, according to the ISAB's "Review of the Comparative Survival Study's Draft 2013 Report."

ISAB's membership is selected to serve the National Marine Fisheries Service, Columbia River Indian tribes, and Northwest Power and Conservation Council by providing independent scientific advice and recommendations regarding scientific issues that relate to the respective agencies' fish and wildlife programs.

The Oct. 15 report is among several reviews completed in October by the ISAB and by the Independent Scientific Review Panel, which reviews for scientific merit programs proposed for funding under the NPCC's Columbia River Fish and Wildlife Program. The reports can be found at: www.nwcouncil.org/

The Fish Passage Center is funded by the Bonneville Power Administration through the NPCC's Fish and Wildlife Program to collect data, largely stemming from fish implanted with passive integrated transponder tags, and evaluate flow and spill measures that are implemented to provide mitigation for impacts to mainstem Columbia and Snake river migration conditions due to hydrosystem development and operation. The hydrosystem is also known as the Federal Columbia River Power System.

The ultimate measure is smolt-to-adult returns, the percentage of fish that swim down the river as juveniles, mature in the Pacific Ocean and survive to return to the Columbia-Snake system as adults to spawn and produce a next generation.

"The CSS is a large-system study that has collected a substantial amount of PIT-tag data from multiple species and stocks over a 17-year period, but to date identification of hypotheses on the causal mechanisms regulating SARs has been limited," the ISAB report says. "The ISAB suggests a comparative approach to identifying hypotheses that may lead to a greater understanding of causal mechanisms."

The Council's program calls for a regular system of independent and timely science reviews of the FPC's analytical products. The ISAB review begins by suggesting topics for further CSS review, then provides general and specific comments on each chapter of the report, and ends with specific editorial suggestions.

"A detailed reevaluation of SAR objectives (2-6 percent) is warranted," the ISAB report's executive summary says. (The ISAB expressed similar sentiments a year ago. See CBB, Oct. 26, 2012, "Review Of Long-Running Salmon Survival Study: Smolt-To-Adult Return Goals Should Be Reassessed")

"These objectives should be reevaluated for each species and Evolutionarily Significant Unit (ESU) of salmon and steelhead based on realistic values needed to support robust viable populations." A total of 13 Columbia River basin groupings of salmon and steelhead populations -- ESUs -- are listed by NOAA Fisheries under the Endangered Species Act as either threatened or endangered.

"Discrepancies in SARs between PIT-tagged and non-PIT-tagged fish reported in other publications raise two important issues that could be addressed now: (1) what are the implications of correcting biased SAR estimates from PIT tags with respect to performance against recovery and Fish and Wildlife Program objectives, and (2) what proportion of US Endangered Species Act (ESA)-listed populations are being PIT-tagged and what are the implications for imposing this additional mortality?

"Further work is needed to analyze the relationship between the ratio of transport/in-river SARs and in-river survival," the ISAB report says.

"With many years of experience now, the CSS needs to identify critical data gaps. What crucial pieces of information are not addressed by the CSS, and what improvements can be made to provide them?

"Some examples provided by the ISAB include the lack of habitat-specific estimates of smolt survival in the estuary, information on how age at maturation affects SARs, the contribution of mini-jacks to SARs, and the relationship between SARs and biomass of adult returns of hatchery and wild salmon.

"The ISAB recommends a new focus on rationalization of the PIT-tagging program given the very large detection infrastructure already in place and the overlapping objectives of the different tagging.

"It may be possible to reduce the numbers of populations and fish that are PIT tagged without significant loss of information, leading to greater program efficiencies at lower cost."

"The ISAB also recommends that the CSS prepare and submit a manuscript for peer-reviewed publication that synthesizes and critically reviews the results of the CSS study.

"Most of the information in the CSS's 2013 report is an annual update of information in previous year's reports. Our summary, therefore, focuses on new information presented in Chapter 2, which develops and describes a simple life-cycle model. In this model, information from multiple populations is used to estimate parameters common to the different populations (ocean survival) while allowing each population to have a different spawner/recruit relationship."

The ISAB in a report completed Oct. 18 also critiqued a NOAA Fisheries statistical modeling effort aimed at improving upon previous efforts estimate hydro system and climate effects on salmonid population viability, and expand on those efforts by covering more populations and habitat restoration actions, as well as improving representation of climate effects, hatchery spawners, and spatial interactions.

The ISAB "Review of NOAA Fisheries' Life-Cycle Models of Salmonid Populations in the Interior Columbia River Basin (June 28, 2013 draft)" can be found at: www.nwcouncil.org/fw/isab/isab2013-5/

A key goal of such life-cycle models is to inform decision makers about the influence of restoration activities on the recovery and viability of ESA-listed salmon in the Columbia Basin.

The NOAA Fisheries models look at potential impacts of habitat restoration actions, hatchery "supplementation," estuary and ocean conditions, climate change, the hydro system, population spatial structure and other factors.

"Chapter 4 describes a novel modeling approach for investigating the likely effects of hatchery supplementation on wild salmon population dynamics," the ISAB report says. "This well-developed investigation used several decades of data for 23 Snake River spring chinook populations.

"The ISAB commends the extensive use of existing data here and in many of the other models. This investigation provides compelling evidence indicating that numbers of hatchery salmon spawning in rivers accentuates density dependence such that lower survival offsets the anticipated benefits of supplementation for spring chinook salmon.

"This modeling approach should be utilized for other species and watersheds when sufficient data exist, and the findings should be incorporated into other life-cycle models."

Two reports were completed by the ISRP in October.

In a "Review of Progress Report for the Upper Columbia United Tribes Wildlife Monitoring and Evaluation Program" the ISRP concluded that the UCUT progress report on its analysis of terrestrial vertebrate and vegetation response to ecological restoration provides "a very good summary of analytical approaches and a thoughtful and rigorous preliminary analysis of data," and thus meets scientific criteria needed to receive funding through the Council program.

The ISRP also on Oct. 15 produced a "Response Review of the Kootenai River Floodplain Ecosystem Operation Loss Assessment Report" from the Kootenai Tribe of Idaho.

"The project was initiated to assess and mitigate the impacts related to the operation of Libby Dam," the ISRP review says. "As described by the sponsors' cover letter, they developed indices that quantify abiotic and biotic perturbations of the ecosystem and used a standardized scale to compare and contrast between indices. In addition, they note that products developed to build these indices (LiDAR, land cover classification maps, etc.) have provided information to other Kootenai River projects, such as the Kootenai River Habitat Restoration Project, the Reconnect Kootenai River with Historic Floodplain Project, and Albeni Falls Wildlife Mitigation Project.

"The ISRP recommends that the project ‘Meets Scientific Review Criteria (Qualified).' The qualifications are that the ISRP would like to review the multi-year restoration plan, including specific goals and 5-10 year, quantitative objectives for their actions. The ISRP would also like to see documentation of progress at regular intervals of 1-2 years."