DNR investigating reports of dead fish on Lake St. Clair

The Michigan DNR is investigating recent reports of dead fish on Lake St. Clair. The Michigan DNR asks anyone to report anything they might find along those lines, such as the dead gizzard shad shown here. (Michigan DNR)

The Michigan Department of Natural Resources is investigating several fish mortalities – particularly of gizzard shad – that have been reported at Lake St. Clair.

A number of samples have been collected to determine the cause. Some of the fish may have been affected by viral hemorrhagic septicemia virus (VHSv), a contagious pathogen, but the DNR is still waiting on confirmation.

Many of the collected fish showed the classic external signs of VHSv: bloody patches on the skin. VHSv first caused fish mortalities in the St. Clair-Detroit River corridor in 2006 and occasionally has been detected in these waters since that time.

The virus is known to infect more than 30 species of Great Lakes fish and has been found in lakes Superior, Huron, Erie and Ontario, along with a few inland lakes. Some species such as lake sturgeon and walleye are very resistant to it and others such as bluegill, largemouth bass, muskellunge, gizzard shad and round goby are very susceptible to the virus. The pathogen causes the fish’s blood vessels to leak, which is why the skin shows bloody patches. This symptom is shared with other pathogens, so testing is needed to confirm if VHSv is involved. Previous research has shown that many fish recover from this virus infection, although there is no treatment.

“The public is encouraged to continue to provide us with reports of fish kills with a focus on kills of more than 25 fish,” said Gary Whelan, research program manager for the DNR’s Fisheries Division. “The public can provide the reports to our fish kill email address at DNR-FISH-Report-Fish-Kills@michigan.gov. This information helps us track this event and determine where best to collect additional samples.”

Anglers are reminded to refrain from moving live fish between water bodies and to properly dispose of bait. Boaters need to make sure their bilges and live wells are emptied prior to leaving a boat launch, and equipment must be cleaned and disinfected after use. Visit michigan.gov/fishing for more information on how those who fish and boat can help limit the spread of fish disease and invasive species.

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