OLYMPIA - A failed water pump cut off the flow of water to juvenile coho salmon at the Issaquah Hatchery last weekend, killing an estimated 500,000 young fish, according to the Washington Department of Fish and Wildlife (WDFW).
The pump that supplies water to the hatchery's egg incubation room failed at approximately 11 p.m., March 12, said WDFW Hatcheries Division Manager John Kerwin. At the time, hatchery incubators were filled with more than one million coho salmon in various stages of development. An estimated 456,000 of the coho died in the incubators.
Kerwin said hatchery staff first attempted to restart the pump. When they were unable to do so, they then moved as many fry as possible from the incubators to an outside rearing facility with a different water source.
Approximately 420,000 coho were relocated from the incubator trays to the raceway, but Kerwin said an unknown number of the relocated fish are likely to die in the coming days because they were too small to survive handling.
"The hatchery staff had to attempt to move the fish, because not doing so would have resulted in 100 percent mortality," Kerwin said.
Kerwin said electricians who examined the pump discovered the motor had burned out. WDFW is replacing the water pump and will install a back-up pump for the egg incubators, he said.
The Issaquah Hatchery typically rears about 450,000 coho salmon to yearling stage before releasing the fish into Issaquah Creek. Another 60,000 coho are reared to sub-yearling stage before they are transferred to net pen facilities for additional rearing.
Additionally, hatchery staff collects and fertilizes several hundred thousand coho eggs from returning salmon for transfer to cooperative rearing projects in the region. The production and release of coho at the hatchery will not be heavily impacted because a portion of these "eyed" eggs are available for use in making up the loss, Kerwin said.
More than two million fall chinook salmon and an estimated 450,000 larger coho salmon reared at the hatchery were unaffected by the pump failure.