Deadly parasite dissolving MN lake fish an urgent priority for U researchers


A gruesome parasite is killing fish in multiple lakes in Minnesota, and university researchers are urgently trying to find its cause and stop its spread.

Cases of heterosporosis have been confirmed in 26 lakes in Minnesota, affecting 15 species, since it was first reported in Lake Bemidji in 1990, according to the University of Minnesota's Aquatic Invasive Species Research Center.

It's been found in well-known lakes including Mille Lacs, Vermillion and Leech, plus Lake Superior.

Researchers have been working on the pathogen for several years, but concerns over its spread have now made it a high priority, particularly given its impact on "economically and ecologically important" species, including yellow perch and walleye.

The parasite has a devastating effect as it dissolves fish muscles, making it look as though the muscles have been cooked or "freezer-burned," so any infected fish caught by anglers are not going to make much of a meal.

KARE 11 reports infection rates in affected lakes can be as high as 30 percent. It is passed by fish eating the spores or flesh from another infected fish.

"I am concerned," researcher Nick Phelps told the TV station. "As far as diseases go, this is a nasty one," but he added that people aren't known to be susceptible to this disease.

Anglers have been warned to ensure their boat and equipment is cleaned if they are moving between lakes, to prevent possible spread of the parasite.

The U has said that field and lab research is underway to estimate how prevalent the disease is in Minnesota's "important fish populations," as well as its potential long-term impact.

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