Michigan kills 31,000 salmon after they contracted disease at hatchery [Video]

More than 31,000 Atlantic salmon raised in a Michigan fish hatchery had to be killed after failing to recover from disease, officials said Tuesday.

The decision followed an unsuccessful 28-day treatment period at the Harrietta hatchery in Wexford County.

It was “gut-wrenching for staff,” even if the fish were just a fraction of the millions raised in hatcheries each year, said Ed Eisch, assistant chief in the fisheries division at the Department of Natural Resources.

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The fish, around 6 inches long, were loaded into a truck Monday, euthanized with carbon dioxide and buried in a pit, Eisch said Tuesday.

The salmon, sick with a bacterial kidney disease, were treated with medicated feed.

“We kind of suspected when we went into the treatment that it might not be effective,” Eisch told The Associated Press.

The unhealthy fish would have posed a …