Fishing News
Studies underway on fish parasite
A previously unknown parasite, Heterosporis, that severely degrades the muscle of yellow perch from Minnesota and Wisconsin lakes has now been reported from Lake Ontario.
Fresh infected fillets are milky white in color appearing almost as if they were freezer-burned or already cooked. This same parasite has now been confirmed as occurring in Minnesota yellow perch from lakes Winnibigosh, Leech, Vermilion, Mille Lacs, Bear, Moose, Cass, and Andrusia, in walleye from Big Sand Lake and northern pike from Clitheral Lake.
These are the first reports of Heterosporis in the Western Hemisphere. It has been previously reported from cultured eels in Japan and Taiwan, cultured freshwater angelfish in France, cultured catfish in Germany, and commercially reared bettas from Thailand. Although researchers have found similarities with the parasite found in Asia, they are describing the North American version as a new species.
Recent laboratory studies by the University of Wisconsin -- La Crosse show that yellow perch, walleye, rainbow trout, channel catfish, and fathead minnows are extremely susceptible to perch Heterosporis infections. Having unusually low host specificity, Heterosporis has potential to become widely distributed in many important sport and commercial fish populations and could be widely translocated by bait fish, stocked fish, and other as yet unknown mechanisms.
Fish in nature would likely be able to become infected by contacting spores from decaying infected carcasses and also by scavenging dead infected fish. Studies are under way to determine if fish can become infected through normal predator-prey interactions. Tissue samples have been sent to the Center for Disease Control and no human danger from eating infected fish could be established.
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