Washington’s campaign to rear more salmon for orcas suffered a setback Dec. 14 as 6.2 million chinook fry suffocated at a Fish and Wildlife hatchery in Pierce County.

The losses amounted to about 9 percent of the 68 million chinook raised annually at Fish and Wildlife hatcheries. The department’s hatchery division manager, Eric Kinne, called the loss devastating and one that won’t be easy to make up.

Increasing hatchery production is part of Gov. Jay Inslee’s proposed $1.1 billion orca-rescue plan. The plan was based on recommendations from the Southern Resident Orca Task Force. Inslee also embraced a recommendation to look at removing four dams on the Lower Snake River to increase fish runs.

The dams are part of a river system that allows wheat farmers to barge grain to export terminals on the Columbia River. Other elements of the orca recovery plan could affect land regulations and water rights.

The chinook fry at Minter Creek Hatchery in Gig Harbor died during an early evening windstorm that knocked out electricity to pumps that constantly flow water through about 900 small trays. Each tray held about 6,800 fry, Kinne said.

Hatchery workers were unable to start a backup diesel generator to keep the water flowing. “It was a mad scramble,” Kinne said.

After a half hour, deprived of oxygen in freshwater, the fish began to die, Kinne said. Fish and Wildlife has not said why the generator did not start. “We’re still investigating the root cause,” Kinne said.

The mishap killed 4.2 million Deschutes fall chinook fry, 1.5 million Minter Creek fall chinook fry and 507,000 White River spring chinook fry. Fish and Wildlife had planned to end the production of White River spring chinook fry, but decided to rear more this year in an early effort to increase prey for orcas.

The chinook were scheduled to be released in May or June. Out of the 6.2 million fry, about 14,700 could have been expected to return after three to five years in the ocean to be harvested or to spawn.

Fish eggs at the hatchery, including roughly 4.2 million chum salmon and 2 million coho salmon, survived the power outage.

The losses were higher than the 2.4 million chinook fry that died when mud, gravel and trees flooded a Kalama River hatchery in southwest Washington during a storm in 2015.

The Washington Farm Bureau, which is represented on the orca recovery task force, said it supported increased hatchery production. It abstained, however, from endorsing the slate of recommendations sent to Inslee, primarily because of the recommendation to study removing the four dams.

The dams generate enough electricity to power a city the size of Seattle, according to the Bonneville Power Administration. The dams have long been criticized by environmental groups as impediments to fish.

The dams were built between 1962 and 1975 and have fish passages. According to NOAA Fisheries, the number of wild spring and summer chinook returning to the river has declined since the dams were built, but increased hatchery production has more than offset any loss of prey base for orcas caused by the dams.

There is no evidence orcas distinguish between wild and hatchery fish, according to NOAA Fisheries, which concluded in 2014 that removing the dams was not necessary to recover orcas.

Inslee said he wants a task force to study whether the hydroelectricity could be replaced with wind and solar power, and whether the barges could be replaced with trucks and trains. The Army Corps of Engineers operates the federal dams. Inslee said a state task force could contribute to a court-ordered environmental review of the dams. Inslee has proposed spending $750,000 on the task force.