Science: Snake River Fish
Calling it a "mature product," the Independent Scientific Advisory Board completed its review of the latest draft of the Fish Passage Center's Comparative Survival Study October 21.
As it has found in each year it has produced the CSS, smolt-to-adult returns of salmon and steelhead out of the Snake River are not meeting the 2 percent to 6 percent SARs goals set by the Northwest Power and Conservation Council. However, fish out of the mid-Columbia River generally had SARs that fell within the NPCC range.
It also found that the effectiveness of transporting fish from the Snake River downstream to below Bonneville Dam decreases as river conditions improve.
The draft CSS -- titled "Comparative Survival Study of PIT-tagged Spring/Summer/Fall Chinook, Summer Steelhead, and Sockeye" -- was released for public review by the Fish Passage Center and the Comparative Survival Study Oversight Committee at the FPC website August 31. Comments were due October 15 and some of the most comprehensive and technical comments each year are those from the ISAB.
This is the ISAB's seventh annual review. The first review in 2010 and all subsequent reviews were called for by the Council's 2009 Fish and Wildlife Program.
"Overall, the presentation is well organized and well refined," the ISAB review document said. "An overarching comment is that connections with larger ecological concerns are not apparent. That is, there appear to be opportunities to involve researchers working on studies of other species, food webs, physiology, contaminants, and disease. Such combined studies might give added insights into mechanisms causing the observed temporal patterns in migration and survival."
The CSS draft report is laid out in eight chapters and three appendices.
In its summary, the ISAB says the first chapter is an overview of the entire CSS report and is similar to previous years, but with recent results added. The CSS in 2016 also added two fish populations that hadn't previously been included -- Okanagan River sockeye and natural-origin summer chinook salmon from upstream of Wells Dam.
But the CSS also says that PIT-tags increased in size from the 9 to 12 millimeters of previous reports to 11 to 12 mm. That could have impacts on tagged fish, the ISAB says, and should be explored.
"If this is a real change, the rationale for the change is needed along with a discussion of potential impacts on the fish (e.g., are larger fish now tagged to accommodate the larger tags?)," the ISAB review says.
The first chapter also outlines three new topics:
Chapter 4 of the CSS report describes overall annual SARs and includes new data.
"Overall SARs of Snake River wild spring/summer Chinook and steelhead fell well short of the Northwest Power and Conservation Council's 2 -- 6 percent SAR objectives, while those from the mid-Columbia region generally fell within this range," the CSS report says. "For Snake River populations, none of the passage routes (in-river or juvenile transportation) have provided SARs within the range of the NPCC objectives."
Among other findings, the CSS report found that "the relative effectiveness of transportation decreases as in-river conditions improve," and that "SARs are highly correlated among wild and hatchery populations within and between regions, indicating common environmental factors are influencing survival rates from outmigration to the estuary and ocean environments."
"It is not surprising that the transport TIR is inversely correlated with in-river survival (Lower Granite Dam to Bonneville Dam)," the ISAB said. "This new analysis identified the value for in-river survival when the benefits of transportation appear to disappear." TIR is the transport to in-river ratio.
The CSS also reported on the relatively large absolute difference in SAR based on PIT-tags versus run reconstruction, the ISAB said. While there is an evaluation of PIT-tag effects on salmon survival, the results will not be ready until after summer 2017. "Potential bias in survival caused by tagging methodology (or in the run reconstruction methodology) is an important issue to resolve, and the ISAB looks forward to the results of this study."
Chapter 5 looks at the association of SARs to life-cycle productivity for wild spring/summer chinook and steelhead populations. Major population declines of these Snake River stocks are associated with SARs of less than 1 percent, and increased life-cycle productivity has occurred in years when SARs exceeds 2 percent, the CSS report says. The historical (pre-1970s) SAR was in the range 4 to 6 percent.
Faced with these figures, the ISAB asked to "what extent might improvements in hydrosystem management, predator control, and estuarine habitat lead to SARs of 4 percent to 6 percent?"
The ISAB recommended five topics for future reports:
The 2016 CSS report is at http://www.fpc.org/documents/CSS/Draft_CSS_2016_1.pdf. It was prepared by the Comparative Survival Study Oversight Committee and the Fish Passage Center (www.fpc.org). The committee includes Jerry McCann, Brandon Chockley, Erin Cooper and Tommy Garrison, all of the Fish Passage Center; Howard Schaller and Steve Haeseker, U.S. Fish and Wildlife Service; Robert Lessard, Columbia River Inter-Tribal Fish Commission; Charlie Petrosky and Tim Copeland, Idaho Department of Fish and Game; Eric Tinus and Erick Van Dyke, Oregon Department of Fish and Wildlife; and Robin Ehlke, Washington Department of Fish and Wildlife.
2015 Salmon Survival Report Updates Smolt-To-Adult Return Data For Columbia/Snake Salmon, Steelhead by Staff, Columbia Basin Bulletin 12/29/15
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