In an attempt to boost survival, the Washington Department of Fish and Wildlife will use a barge next month to move about 20,000 Tucannon River spring chinook smolts through the Snake and Columbia rivers hydrosystem.
The agency also will truck the same number of smolts from the Tucannon Hatchery and release them near the river’s mouth. But most of the 130,000 juvenile spring chinook raised at the hatchery will be released from the facility, directly into the river.
Tucannon River spring chinook are part of the Snake River run that is protected as threatened under the Endangered Species Act.
It is the only Snake River population wholly within the state of Washington and it has been struggling for decades. A recent report listed the population to be in crisis and poor juvenile survival is one of the main reasons.
“We have been in a downward spiral for the last five years,” said Joe Bumgarner, a fisheries biologist with the Washington Department of Fish and Wildlife at Dayton. “We are hanging on.”
Last year, 273 adult spring chinook returned to the river. While still low, it was a pleasant surprise and better than the return of about 215 in 2021 and far superior to the 80 fish that made it back in 2020. This year, fisheries managers are forecasting a return of about 100 adults.
“If we could get back 600 to 800 returning annually, people could get more comfortable,” Bumgarner said.
Fisheries managers track juvenile chinook as they migrate downstream through the hydropower system and ultimately to the Pacific Ocean. In some years, as few as 30% of the fish released from the hatchery make it to Lower Monumental Dam, a distance of about 40 miles. AAs many as 30% can perish between the hatchery and the Tucannon’s mouth.
Bumgarner said the strategy of barging and trucking will allow researchers to determine where most of the mortality is occurring.
“This is definitely us thinking outside the box — what else can we do to help this population?”
From the 1990s and into the early 2000s, the majority of salmon and steelhead smolts from the Snake River were collected at dams like Lower Granite and transported through the hydropower system in barges.
The strategy, which speeds migration and protects fish from predation and injury during dam passage, worked better for some populations than others. But it was considered insufficient as a blanket fish recovery strategy. It led to higher rates of straying and required more handling of the fish, which increased stress and injury.
Barging is still used today, but most smolts are now left to migrate in-river. The current strategy calls for mandatory spill at the dams to speed river flows and help the fish pass dams via their spillways, a safer route compared to going through turbines or elaborate fish bypass systems.
David Johnson, director of the Nez Perce Tribe’s Department of Fisheries Resources Management, said dams and the predator-friendly reservoirs they create are hammering the young fish.
He notes that the Tucannon is the only river in the Snake River Basin that empties directly into slackwater. He calls the run a “poster child” for dam breaching.
“The mortality those fish face from release down to the first dam is greater than mortality fish face anywhere else in the Snake system to the first dam. That is huge mortality,” he said. “Logically it’s understandable because the fish are going directly into a slow-moving reservoir that is a haven for predators and causes all kinds of problems for the fish.”
There is a risk both to barging and releasing smolts at the mouth of the Tucannon. Juvenile fish that make the journey from their home waters to the mouth of the Columbia River via barge often display a higher rate of straying when they return as adults.
Those that do make it back to the Tucannon River may fail to progress upstream to the hatchery or the prime spawning habitat.
But the fish are reared on water from the Tucannon and fisheries managers hope that helps them find their way home.
“I think our strategy of having (the smolts) over winter on Tucannon River water for six to seven months should be enough to give them that cue, when they do come back, to go all the way. But we don’t know,” Bumgarner said.
About $2 million each year is invested in projects to improve spawning habitat on the Tucannon River. Biologists believe the work will benefit fish. But they need to see higher survival and more robust returns to really know. Thus far, the new habitat is largely empty.
“The ultimate goal is to get more fish on the spawning grounds,” Bumgarner said. “We haven’t had a lot of fish on the spawning grounds, whether it’s hatchery fish or natural fish.”
The tribe and department also are exploring moving some of the Tucannon River fish into a hatchery program on the lower Columbia River. The idea is to bypass the hydrosystem altogether and ensure the genetics of the run is preserved.
“These are drastic measures we are having to take with that population of fish,” Johnson said. “I think it’s a troubling sign and I think it’s very much a poster child for why we need to do something different. For a tributary like the Tucannon that feeds right into a reservoir — the fish don’t have much of a chance.”
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