Upper River Spring Chinook Only
by Laura Berg
"A likely, though not conclusive, explanation is that over the past decade spill volumes
at mid-Columbia projects have decreased while spill in the Snake River has increased.
Of 13 listed salmonid species in the Columbia River Basin, only upper Columbia River natural-origin spring Chinook show "no statistically significant upward trend in abundance," wrote Stacy Horton, a Washington state policy analyst for the Northwest Power and Conservation Council, in a memo introducing a Sept. 13 panel presentation.
The latest data for upper Columbia spring Chinook shows that the 12-year geometric mean return of adult fish is 1,214, or nearly a quarter less than the goal, according to a slide prepared by the Upper Columbia Salmon Recovery Board (UCSRB).
"The recovery goal is for a return of 4,500 adult fish," UCSRB's Greer Maier told Council members.
The upper Columbia River spring Chinook evolutionarily significant unit (ESU) was listed as endangered under the Endangered Species Act in 1999.
A NOAA Fisheries five-year status review released earlier this year said upper Columbia spring Chinook populations in the Entiat and Methow river basins remained below viability thresholds, which means their numbers are so low their risk of extinction exceeds 5 percent. Only the Wenatchee River population surpassed the 5-percent threshold.
The upper Columbia spring Chinook ESU consists of fish from the Entiat, Methow and Wenatchee river basins. Spring Chinook are extirpated from the upper Columbia's Okanogan River basin.
In presentations to the Council, representatives of Chelan, Douglas and Grant PUDs said that operations at Wells, Rocky Reach, Rock Island, Wanapum and Priest Rapids dams are achieving no net impact, through a combination of structural modifications and other fish-passage improvements, hatchery programs and habitat-restoration actions.
Tom Kahler and Tom Dressler, fisheries biologists for Douglas County PUD and Grant County PUD, respectively, said their projects are meeting the 91-percent combined juvenile and adult survival rate at each dam. The survival-rate requirements are part of their FERC licensing agreements. Chelan County PUD's presentation, which said its dams were also in compliance, was given by Dessler.
Washington Department of Fish and Wildlife biologist Andrew Murdoch, who presented at the Sept. 13 meeting, indicated in an email to NW Fishletter that hatchery reforms have also been undertaken.
He and Maier said that partly in response to the poor showing of upper Columbia spring Chinook stocks, hatchery reprogramming and other measures have reduced the number of hatchery spawners used as broodstock and the number of hatchery fish on spawning grounds in the Entiat, Methow and Wenatchee basins.
Maier, the UCSRB science program manager, said more needs to be done to determine hatchery effects and to identify factors at play in the reproductive success or failure of hatchery spring Chinook.
Such changes in artificial-production strategies are also actions NOAA Fisheries recommended in the current five-year status review.
Habitat rehabilitation, too, requires more work, Maier said. She noted that so far habitat restoration has focused more on areas used by steelhead than areas used by Chinook.
"Habitat problems are still common throughout the region and many more habitat improvements are likely needed to achieve viability," the NOAA Fisheries' 2016 status review says.
As far as harvest of these spring Chinook stocks go, "catch rates remain relatively low and stable," the five-year review states.
Ocean fisheries take very few upper Columbia springers and "for practical purposes, is assumed to be zero," the review said. While incidental catches occur during spring fisheries in the mainstem Columbia River, the harvest is limited to a rate does not exceed 5.5 to 17 percent. The average take in recent years has been 10.7 percent, the NOAA document said.
Even with all of the four H's-hydropower, hatchery, habitat and harvest-being addressed to one extent or another, there's still a problem.
Washington Council members Guy Norman and Tom Karier asked whether life-cycle modeling had been done to estimate survival in the mainstem and ocean.
"We need the mainstem, estuary and ocean data to complete life-cycle models," Murdoch replied. Only modeling for the Wenatchee is finished.
Life-cycle modeling can be used to identify survival bottlenecks in complex natural systems and to determine which restoration actions are efficacious.
Norman said that historically there were similarities between Snake River and upper Columbia River stocks, but that's not the case recently. What's happening, he asked.
"We don't have a definitive answer," Murdoch said.
Recent comparative survival studies, however, indicate a difference in the smolt-to-adult survival ratios between Snake River migrants and upper Columbia stocks out-migrating in the same year.
"The data show poorer reach survival between Rock Island to McNary (for upper Columbia River stocks) than between Lower Granite to McNary (for Snake River stocks)," the Columbia River Inter-Tribal Fish Commission's Spirit of the Salmon Plan states.
"A likely, though not conclusive, explanation is that over the past decade spill volumes at mid-Columbia projects have decreased while spill in the Snake River has increased. The mid-Columbia dams have actually reduced spill over the years as structural changes have been implemented," the plan's analysis says.
In an email to Fishletter, Maier pointed to other potential survival bottlenecks.
"This year's spring Chinook run to the upper Columbia is the smallest run since 2007 at just under 17,000," she said. "The wild run is likely less than 3,000 fish.
"Of those 3,000 or so fish, only about half will survive to spawn based on recent estimates of pre-spawn mortality," she said. The UCSRB presentation also identified pre-spawn mortality as a problem.
"Another emerging issue has been predation by pinnipeds in the lower Columbia. We have lost between 50-60 percent of our total spring Chinook run in the last two years in the lower Columbia," she said.
"Much of that mortality is likely due to the large numbers of pinnipeds in that area the last two years. Our spring Chinook runs are some of the earliest to arrive in the estuary and therefore are hit particularly hard," Maier said.
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