Muskies Infected With Rare Disease In L

Thanks for the interest in this subject. First let me remind everyone that we really don't know much about this disease or its implications for the muskie population in Lake St. Clair at this time. I will be meeting with our fish pathologist shortly to discuss our sampling strategy for the coming open water season.

I would like to try and clear up a few points based on the little information we do have at this time.

1. This disease is a systemic infection, in other words, the bacteria occur throughout the fishes' body... the skin lesions are just a particularly ugly and visible external sign of infection.
2. The external lesions can become secondarily infected by other organisms such as other bacteria and fungus, but these Rickettsia lesions are very distinctive in appearance when closely examined. My verbal description would be "roughly circular, up to about an inch in diameter, puffy pink or red colored scab-like sores."
3. Unfortunately, there are several other diseases that result in red colored sores or spots on the skin of fish. In fact, simple abrasions will often produce a reddish sore spot on fish skin. During my 11 years of conducting fish surveys on Lake St. Clair, I have NOT observed any lesions like the ones I've seen on the infected Muskies, on other species of fish in Lake St. Clair.
4. Muskies in Lake St. Clair are often parasitized by native silver lamprey. The silver lamprey wounds are circular and sometimes bloody in appearance. They could easily be confused with the Rickettsia lesions. There may be some link between the lamprey wounds and the Rickettsia - but that is pure speculation at this point.
5. About 15-20% of the muskies we examined last spring bore the external skin lesions indicative of the disease.
6. Muskie fishing reports from last season were good. There is no sign based on fishing success that muskie abundance has declined.
7. There have been NO reports of unusual muskie mortality on the lake over the past couple years. Hopefully, this is an indication that this disease isn't a serious source of mortality for wild muskie.

Thank you again for your interest and the opportunity to share the limited information we currently have available about this subject. As we gain more knowledge on this situation, I will be happy to keep you updated. - Mike Thomas, Fisheries Biologist, Mt. Clemens Fisheries Research Station

Thanks Mike. As we have talked a few times, this does sound strikingly filmier to what many of us have seen on some smallies in St. Clair & Erie. Of course none of us are trained enough to make a diagnosis. I know you have said, “I have NOT observed any lesions like the ones I've seen on the infected Muskies, on other species of fish in Lake St. Clair.” One possible reason may be where most of these fish seem to be caught. My experiences have been in the South Canadian shoreline or in Lake Erie. They also seem to come from areas with heavy concentrations of rocks/zebra mussels. Nothing anywhere else. Sounds like DJK’s experiences were similar with the exception of some fish caught “up North” later in the year. Again this is all speculation on my part. I think the best thing to do is to get a fish to you once the season opens. I had promised some pictures that I took last fall, but for some reason I can’t find them?!?!