Michigan Department of Natural Resources euthanizes more than 31,000 Atlantic salmon

The Michigan Department of Natural Resources recently had to euthanize about 31,000 Atlantic salmon at the Harrietta State Fish Hatchery in northern Michigan's Wexford County.

The fish were sick with bacterial kidney disease (BKD), according to the DNR.

BKD is a bacterial disease that causes mortality in trout and salmon and is believed to be largely responsible for the decline in the Great Lakes Chinook salmon population in the mid-1980s, according to the DNR.

The DNR discovered BKD in the salmon in early April during a prestocking inspection. Michigan State University Aquatic Animal Health Lab staff confirmed the presence of Renibacterium salmoninarum, which causes BDK.

The fish were prescribed a 28-day antibiotic treatment that was mixed in their feed. However, the sick fish were not feeding well and didn't eat enough of the antibiotics to eliminate the pathogen.

The treatment was completed May 17, but was not effective in eliminating the infection.

The DNR then sent another group of fish to the lab for analysis and found internal signs of active disease.

More: Large numbers of fish dying in Michigan's Lake Macatawa

“The bacteria that causes bacterial kidney disease is listed as a Level 1 restricted pathogen in the Model Program for Fish Health Management in the Great Lakes,” said DNR Fisheries Division Assistant Chief Ed Eisch in a news release. “Fish that are positive for Level 1 restricted pathogens can be stocked where the pathogen is already known to exist, but only if they are free of signs of disease. This lot of fish still shows signs of active BKD so they cannot be stocked.”

“Having to make the decision to dispose of these diseased fish hurt, but it was clearly the right thing to do,” Eisch said. “The Atlantic salmon fishery is highly valued, but first and foremost, we have a public trust responsibility to protect the aquatic resources of the state of Michigan. Stocking fish known to be actively suffering a disease outbreak would be counter to that.”

Atlantic salmon are also reared at the Platte River State Fish hatchery located about 15 miles west of Traverse City. The fish at that facility were healthy and stocked in four locations in the state.

This article originally appeared on Detroit Free Press: Michigan Department of Natural Resources euthanizes more than 31,000 Atlantic salmon