Spring/Summer Fish Die-Offs
Shortly after Memorial Day last year, watershed residents began to observe fish die-offs on Prior and Spring Lakes. This was a common sighting in the lakes around Scott County during late spring/early in 2014. Testing confirmed that columnaris bacteria was the cause of the die-offs in Carls (McMahon) and Cedar Lakes, and it is suspected that this bacteria was also the likely cause of the die-offs in Prior and Spring Lakes.
As we approach the same season this year, it is important to keep in mind that the die-offs caused by Columnaris disease are a natural occurrence and only affect a small percentage of the fish populations in our lakes. There is no known cure, but is believed to have little effect on the long-term health of fish populations.
Columnaris disease is caused by a bacteria that is constantly present in fish populations, but does not typically cause death except during spring spawning season when fish are stressed. Most commonly observed die-offs are of crappie and sunfish populations. Symptoms of Columnaris disease are discolored patches, sloughing of scales and eroded gill filaments. The DNR recommends that diseased fish not be consumed, but healthy fish from the same lake can be safely eaten.
If you observe large fish die-offs on any of the lakes, please take a look at the condition of the fish and any signs of Columnaris disease. Report any findings within the Prior Lake-Spring Lake Watershed District to Maggie Karschnia, Water Resources Project Manager at 952-447-9808 or firstname.lastname@example.org.