A terrifying fish parasite

[Lee Borgersen]

  Fish Parasite Infects 26 Minnesota Lakes

                       


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A terrifying fish parasite in Minnesota has now spread to 26 lakes in the state and 15 different species, according to researchers from the University of Minnesota. The parasite is called heterosporis, and the effects it can have on fish are rather grisly.

“As far as diseases go, this is a nasty one,” Nick Phelps, a researcher with the university’s Minnesota Aquatic Invasive Species Research Center, told KARE 11.

Heterosporis is a microscopic parasite that can infect the muscle tissue of freshwater fish, such as yellow perch. Once there, the parasite begins to produce millions of spores that break down and liquefy muscle matter, replacing entire sections of the fish with white, opaque spores. The Minnesota Department of Natural Resources reported that in some cases, fish have become little more than live, floating vessels for the parasite’s spores, which are then released into the water and contaminate other fish.

It sounds like the plot of science fiction horror movie, but researchers assert the parasite is becoming a very real problem for the state’s commercial and recreational fishermen.

“When you have lakes that have 30-percent (of the fish) infected you can imagine how big of an impact this may have to fisherman trying to catch the fish,” Phelps said. “When you have something that liquefies tissue and you don’t know a lot about the biology and the ecology of it that is cause for concern.”

The parasite seems to have no effect on humans. Cooking infected fish is also believed to destroy the spores, although many anglers are skeptical of eating fish affected by the disease. Wildlife officials recommend destroying any infected fish caught by burning the flesh or burying it.

Infected species include popular game fish such as walleye, northern pike, burbot, and rock bass. State officials added that there is currently no treatment or defense against the parasite, but anglers can help by not releasing infected bait minnow into new lakes. Phelps said he hopes his research will lead to more insight on the disease, and how biologists can begin to combat the parasite. A list of the affected lakes in Minnesota can be found at the research center’s website.



Photo:

What the spores look like on an infected fish. Image courtesy Minnesota DNR.


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Photo:

A walleye with a partially digested fish in its mouth. Neither of these fish are infected with heterosporis, however fish can also contract this parasite by eating affected prey.


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[Lee Borgersen]

                                          More............

 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.

Lakes affected by fish parasite
Affected lakes in Minnesota.

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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[Onin24Eagle]

I saw this in perch on Roy Lake on the border of Mahnomen and Clearwater counties.  Reported it to the DNR but never heard back.  The lake had a minor winterkill after that and I haven't seen it in any fish in that lake since then but there are very few perch in there compared to back then.