Dept. of Game, Fish and Parks
For Immediate Release: Wednesday, June 5, 2002
For more information:  Rick Cordes, 642-6920

PARASITE MAY INFECT YELLOW PERCH

PIERRE -- A little known parasite that infects the muscle tissue of yellow perch could potentially spread to South Dakota. The microscopic parasite is named Heterosporis and has been observed in yellow perch from Minnesota, Wisconsin and Lake Ontario.

"To date, there are no known reports of the parasite in wild yellow perch populations in South Dakota," said Game, Fish and Parks Fish Health Specialist Rick Cordes. "Department officials are concerned that the parasite could be introduced to South Dakota waters by the movement of boats and live fish from infected waters in Minnesota and Wisconsin. Laboratory studies have shown that other fish species, including walleye, rainbow trout, and fathead minnows are susceptible to Heterosporis parasite."

The parasite infects fish muscle cells causing the texture and quality of fish fillet to change. "The flesh will look milky white and granular in texture, appearing as if they were freezer burned or cooked," Cordes said. "The muscle degeneration only affects the appearance of the fillet, but there is no evidence of mortality to the fish. Although anglers may regard heavily infected fillets inedible, there are no known reports of the parasite infecting humans eating infected fillets. "

Fisheries biologists will be surveying South Dakota’s wild yellow perch for the parasite this summer. Anglers are also asked to make their own observations for yellow perch fillets that may be characteristic of the parasite infection. "They should report any unusual yellow perch fillets to department conservation officers or fisheries biologists," Cordes said. 

In addition to making observations for the parasite, the department is encouraging all boaters and anglers to wash their boats, livewells, trailers and any other places that may hold water, especially if they have had their boats in waters outside of South Dakota. "This is the same request that is asked of boaters for the other numerous aquatic nuisance species that may impact the waters of South Dakota," Cordes said.

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