Touched with success, Yakama Nation Fisheries efforts to build returns of once-extinct coho salmon to the mid-Columbia River region are branching out, with hopes of infusing fish into the fingertips of central Washington’s Yakima River basin.
“More coho are venturing into the tributaries” of the upper Yakima River and one of its main tributaries, the Naches River, said Todd Newsome, Yakama Nation Fisheries’ lead for the Yakima Coho Project.
Last week the last of the gates were raised at four coho “acclimation” sites in the upper Yakima, allowing more than 1 million hatchery reared coho smolts to decide when to launch their migration toward the Pacific Ocean. With good fortune many will grow and mature for a return trip to spawn in the wild, and/or offer themselves as broodstock for a next generation of hatchery fish to buoy the reintroduction effort.
Coho salmon were in 1985 judged extinct in the Yakima River basin, due in large part to overfishing and human development that sapped streams of water, threw up barriers to upstream passage and otherwise altered key habitat.
With work ongoing to correct some of those habitat disruptions, the Yakama Nation, funded in large part by the Bonneville Power Administration, began an effort in 1996 to reintroduce coho to the Yakima, and other central Washington tributaries to the Columbia River like the Wenatchee and Methow rivers.
“Our averages are coming up pretty fast,” Newsome said of returns to the Yakima that have ranged between 4,000 and 6,000 in recent years. Relatively random outplantings of available fish during the late 1980s produced returns of a few hundred.
But the more recent, concerted efforts offer hope. Newsome said he would like to see a bumper crop of 20,000 spawners returning to the Yakima system within the next few years.
“That’s my goal,” he said. Overall, the program would like to see annual totals in the 12,000 to 15,000 range, including from 3,000 to 5,000 naturally produced fish. The 2012 return included more than 4,500 fish as counted at Prosser Dam in the lower Yakima. More than half of those coho were naturally born. The peak count was just over 9,000 in 2009.
The process was started with the outplanting of lower Columbia coho stocks in hopes they would find their way to the ocean and back again to spawn in their new home. It has worked, with the program for the past four years drawing broodstock only from fish that started and ended their life cycle in the Yakima basin. That has ended a dependence on out-of-basin fish.
“We’re in the process of solidifying our in-basin program,” Newsome said.
A next phase of the Yakima project would be the construction within the next few years of a hatchery to rear young coho locally. Young fish are now reared elsewhere and returned to the basin for release.
Yakima Fisheries has to this point used the four acclimation sites on the upper Yakima and the Naches but Newsome said they could eventually be phased out if other release strategies prove out.
Three techniques are being studied, including the transport of smolts farther up in the tributaries to the Yakima and Naches rivers.
YN biologists are also experimenting with the outplanting of younger fish – parr – into those smaller tributaries. That “scatter planting” of fish has shown promise, with relatively high survival.
“The method of seeding all tributaries means you let the fish go out on their own and see if tributaries will support natural production or if we need to supplement,” said Dave Fast, senior research scientist with Yakama Nation Fisheries. “Our aim is to establish release sites and strategies that optimize natural reproduction and survival.”
The “volitional” release of fish from the existing acclimation sites is a fine tuning that seems to be working well. The young fish are put in off-channel ponds, usually in March, to allow them to “imprint” on that section of the river in hope they return there to spawn. Volitional release means fish can leave when they chose to leave. That happened last week when the pond gates swung open.
Originally, juvenile coho were held until late May, which did not prove to be optimal timing for them to migrate to the ocean, Newsome said.
“With volitional releases beginning in 2003, coho numbers began to rise,” Fast said.
“With volitional release we will lift the screen from acclimation pond to tributary,” Newsome said. “Generally there is a big push of fish for a couple of evenings, then fish will trickle out until the first of May when the remainder will head out.”
The Yakama Nation has additional coho projects in the Wenatchee and Methow basins, which are also funded by the Columbia Basin Fish Accords.
The Yakama Nation’s long-term vision for coho is to reintroduce a sustainable, naturally spawning coho populations which provide significant harvest in most years throughout the Columbia River basin.