A disease of trout and salmon caused by the bacterium Renibacterium salmoninarum. The disease is systemic but derives its name from off-white bacterial lesions in the kidney. In later stages many organs may become affected and the body cavity may become filled with fluid.

This disease has been thought to be responsible for mortalities of chinook and coho salmon in Lake Michigan over the past decade that led to dramatic declines in those fisheries. In 1993, Fisheries Division began screening all salmonid adults and eggs during spawning operations to detect the presence of BKD. All fish and eggs that test positive are destroyed.

The bacterium that causes BKD is endemic in Michigan lakes so total eradication is not probable. The screening process during spawning is the best available control measure to reduce the incidence of the disease by using fish that are less susceptible to it. This process uses the natural selection process to reduce the impact of the disease on our fisheries.