Return of the sockeye salmon
By Dylan J. Darling
August 25, 2012
After decades of absence from the Deschutes River, sockeye salmon are running again.
Returning as adults from a year or two in the Pacific Ocean, the fish are the latest to be reintroduced above the Pelton Round Butte dam complex, which forms Lake Billy Chinook near Madras. As of Friday, 77 of the fish had returned to the complex since late July, according to scientists monitoring the fish.
The run is expected to continue into next month, but it is unclear how many more fish will return.
“We are still learning about the run and how long it will last,” said Mike Gauvin, Oregon Department of Fish and Wildlife mitigation coordinator at the dam complex.
The three dams in the power-producing Pelton Round Butte complex became an obstacle for sea-run fish when it was finished in 1964.
A fish ladder and a tram guided fish returning from the ocean around the dams, but their young became lost in the currents of Lake Billy Chinook when they attempted to swim to the ocean.
In 1968, a hatchery was built and upstream passage for the sockeye ended as the hatchery focused on the other runs of fish. Swimming mainly in Billy Chinook, the sockeye became kokanee, landlocked salmon, Gauvin said.
Now the sockeye are re-emerging from the kokanee as a result of a new route to the ocean. A $100 million submerged water tower — paid for by Portland General Electric and the Confederated Tribes of Warm Springs, the co-owners of the dams — was completed in 2009. It creates a current that draws in young fish. The fish are collected and then sorted, with chinook, sockeye and steelhead loaded into trucks and driven around the dams.
The chinook were first to arrive this spring, followed by the sockeye now. Steelhead are still to come.
Last year, the first fish to pass through the tower when they were young and return as adults from the ocean started appearing at the dam complex, with all of them taken to the Round Butte Hatchery for spawning. There were seven chinook, 19 sockeye and nine steelhead.
This year 49 spring chinook returned to the dam complex, with 24 of them released into Billy Chinook and the rest going to the hatchery, said Steve Corson, spokesman for Portland General Electric.
All of the 77 sockeye to return this year have been released into Lake Billy Chinook, 31 of them carrying radio transmitters, he said.
“The majority of relocated sockeye have been (tracked) in the upper Metolius River Arm of Lake Billy Chinook, several of them have started to enter the Metolius River,” Corson wrote in an email.
That’s where scientists expect the sockeye will spawn, Gauvin said.
The chinook run on the Deschutes this year was lower than expected for undetermined reasons, but sockeye runs around the entire Columbia River Basin are strong. Each species of salmon has a different life cycle, with the larger chinook typically spending more time at sea and going to different parts of the ocean than the sockeye.
Scientists say the differences could explain why one run of fish is up while another is down.
As the study of the sockeye on the Deschutes River starts in earnest, Gauvin said the fish are already coming back bigger than the kokanee that spent their lives in Billy Chinook. While the kokanee are 10 to 14 inches long, the sockeye are 19 to 23 inches long, he said. Female kokanee carry about 500 eggs and the sockeye have about 1,500 eggs.