Anglers will give up a portion of their share of the Clearwater River spring chinook run this year on the theory that it will pay dividends in the future.
By working together, managers of hatcheries in the Clearwater Basin have found ways to increase their juvenile fish-rearing capacity by about 1 million fish per year. That could lead to considerably more adult chinook being available for harvest down the road.
For example, Joe DuPont, regional fisheries manager at the Idaho Department of Fish and Game at Lewiston, said if a hypothetical 1 percent smolt-to-adult return rate were applied to those 1 million extra smolts, it would lead to an extra 10,000 adults. Subtract the 1,000 or so needed for spawning, and 9,000 more fish would be available for sport and tribal anglers to split.
But to raise more smolts, hatchery managers have to collect more adults for spawning. Those adults will come out of the number of fish available for harvest.
“We are going to collect enough adults to bump it up 1 million,” DuPont said. “All of the hatchery managers looked at their programs and all of them contributed to the increase except Kooskia (National Fish Hatchery), which is already maxed out.”
The cooperating hatchery managers include the state, the Nez Perce Tribe and the U.S. Fish and Wildlife Service.
That boost of 1 million more smolts to be raised starting this year is on top of smolt production gains realized in recent years from similar efforts.
For example, DuPont said in 2008, the four hatcheries in the Clearwater basin produced about 3.65 million smolts and 1.2 million younger pre-smolts. This year, the hatcheries will work to raise 5.58 million smolts and 925,000 pre-smolts, an increase approaching 2 million.
DuPont said managers at Dworshak National Fish Hatchery and the Nez Perce Tribal Hatchery found they could increase the density of juvenile fish in raceways and holding ponds without sacrificing growth rates or fish health. At the state-run Clearwater Hatchery, some adult holding ponds will be used to raise juvenile fish. The U.S. Fish and Wildlife Service is also providing some space at Lyons Ferry Hatchery near Starbuck for juvenile fish production. Chinook raised there will be released in the Clearwater basin.
“It’s a big deal, assuming we can get to that 1 percent smolt-to-adult return rate,” DuPont said.
The actual rate varies from year to year. Between 2007 and 2009, DuPont said the rate was 0.4 percent for juvenile fish released in Red River and 1.13 percent for juveniles released in the Selway River.
Even though more adults will be reserved for spawning this spring, DuPont said a preseason prediction calls for 4,500 adult chinook being available for harvest in the Clearwater and its tributaries this spring, compared to an actual harvest of about 3,700 last year.
Becky Johnson, director for fish production for the tribe’s fisheries division, said the increases will help the hatcheries get closer to the goal of producing enough spring and summer chinook to get a return of 58,700 adults. The goal comes from the Lower Snake River Compensation Program, which funds many hatchery programs in an effort to compensate for chinook killed at the lower Snake River dams.
“We may have met that number once since the Lower Snake Comp program began in the 1980s,” she said. “We are far below returning the amount of adults needed to meet that mitigation goal.”
Johnson also credited the increase to cooperation among the agencies that operate the hatcheries.
“In the last five years or so we have really started to be way more coordinated and work together to find those efficiencies and find ways to be more effective and raise more fish.”
