A motherload of sockeye salmon – 10,000 in all – is beginning to fan out into the many tributary fingers that feed central Washington’s Lake Cle Elum, with Yakama Nation biologists chasing them.
Many of the sockeye spawners, trapped at Priest Rapids Dam on the mid-Columbia River, were equipped with acoustic tags before being hauled by truck to the lake and released. The Yakama Nation developed an agreement with Grant County Public Utility District to use its Priest Rapids Dam off-ladder adult fish trap to collect sockeye for the reintroduction effort.
Now that the spawning season has arrived, the biologists can largely from boats monitor the tagged fishes movements to determine if they spawn, and where.
The monitoring effort has been ongoing for about two weeks and will continue into November, according to Yakama Nation biologist Brian Saluskin. The fish relocations are a part of the tribe’s efforts to reintroduce sockeye and other fish species to upper reaches of the Yakima River basin that have largely been blocked off to salmon for decades by a series of dams.
The Cle Elum River flows into the Yakima River and then the Columbia. The sockeye trapped at Priest Rapids were part of a record Columbia River sockeye run bound for the Wenatchee and Okanogan river basins upstream of the Yakima this year.
The program started with the capture and release of about 1,000 sockeye in 2009. Their offspring, an estimated 80,000 strong, emerged from the lake in 2011. And those that survive to adulthood are expected to start returning from the Pacific Ocean in 2013 as adults.
The juvenile fish escape downriver via a temporary passage device at the dam – a wooden flume in the spillway. Passage success is dependent on river conditions. High spill years are beneficial under the current passage scenario. Juvenile emergence is monitored at Roza Dam on the Yakima and a juvenile trap near Prosser, Wash.
The releases increased to 2,500 spawners in 2010 and then 4,500 last year, thanks to what has been a succession of strong sockeye returns. The agreement allows the trapping and relocation of up to 3 percent of the run.
Spawning takes place mid-September through November. Tribal officials say that from the “Bridge to Cooper” sockeye are easily visible. The Cooper River flows into the Cle Elum River just upstream of the head of the lake.
Salmon nests or redds can be seen further north in Salmon la Sac Creek.
The salmon to spawn in September-October are the Wenatchee stock and the Okanogan stock typically spawn from October-November. Saluskin said that last year, based on genetic tests, it is estimated that 15 percent of the transported sockeye were from the Wenatchee and 85 percent were from the Okanogan.
The Wenatchee fish seem to have a tendency to head farther up into the tributaries to spawn in scarcely covered gravels while the Okanogan fish stay lower in tributaries where there is 2-3 feet of water.
“Usually they’re hanging out closer to the lake,” Saluskin said of the Okanogan.
But with the flood of fish brought into the system this year, the dynamics could be changing.
“They’re all through the system already,” Saluskin said. Fish have been found spawning in a number of locations where they haven’t been seen in past years. Those spawning grounds can be in smaller tributaries and side channels as well as in rivers such as the Cle Elum and Cooper.
After the sockeye hatch out, the young fish swim downstream and spend about a year rearing in the lake before heading downstream toward the ocean. Typically they spend 2 years maturing in saltwater before heading back to freshwater to spawn.
The releases and spawning monitoring are part of a cooperative investigation involving the U.S. Bureau of Reclamation, the Yakama Nation, Washington, other federal agencies and others to study the feasibility reintroducing sockeye and other species and, if warranted, providing fish passage at the five large storage dams that are part of the Bureau's Yakima irrigation project. Construction of the dams began in 1910.
The dam blocking the Cle Elum River, which is a tributary to the Yakima River and then the Columbia River, was built in 1933.
Fish that would be expected to benefit from improved passage include sockeye, coho and spring chinook salmon, and Pacific lamprey. The project also would benefit the Upper Middle Columbia River steelhead and bull trout, two species listed as threatened under the Endangered Species Act.