Hatchery pump malfunction kills 600,000 salmon
The deaths accounted for 70 percent of the 850,000 newly hatched coho at the Lower Elwha Klallam tribal fish hatchery.
"It's pretty severe," said hatchery fish manager Doug Morrill.
The salmon were in their alevin stage, meaning they had freshly emerged from their eggs. At hatcheries, they remain in incubation trays while feeding from their yolk sacks, which hang attached to the underside of their bodies and provide vital nutrients until absorbed.
The pump apparently overheated late on Jan. 29 or early the next morning and prevented water from circulating as required by the alevins, Morrill said. The hatchery's failure-alarm system didn't catch the problem, because it was designed to detect power outages, not pump failures.
The hatchery is looking into a new warning system that should prevent another such incident, Morrill said.
The tribe is the only group which spawns Elwha coho, a non-threatened and unlisted species.
Hatchery officials are working with state scientists to replace as many of the lost fish as possible. Surplus juvenile coho -- perhaps up to 150,000 of them -- from the Washington Department of Fish and Wildlifes Dungeness Hatchery have been targeted for transfer to the Elwha, but first, scientists want to ensure the transfer won't have negative genetic effects.
Even if the transfer is approved, the number of coho released into the Elwha River in spring 2005 will be less than half the norm.
Older coho in the hatchery's outside ponds, set for release this spring, were not affected by the malfunction, which was isolated to the pump supplying the incubation room, Morrill said. Steelhead eggs were not affected because they had not yet hatched and were able to survive in standing water.
Coho released from the hatchery return to the Elwha at a rate of 0.6 to 1.2 percent.
The lost alevin were spawned from adult coho which returned last October and November. Alevin emerge about six weeks after fertilization. The young fish are raised for a year before being released, and surviving adults return from their ocean voyage a year later in the fall.
However, a certain number of coho always return after only six months while others stay at sea for 2 years, and in all there are three coho runs that return to the river in alternating years.
"Over time, that overlap of the three cycles will back-fill any kind of a loss," Morrill said.
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