DNR: Deadly virus may affect thousands of fish
A variety of fish in Lake St. Clair have tested positive for a hemorrhagic virus, indicating the infection is spreading to “more species and is likely to affect tens of thousands of fish,” the Michigan Department of Natural Resources said Monday.
In mid-April, state officials began investigating resident reports of several fish deaths in Lake St. Clair. Officials initially believed the fish kill was primarily comprised of gizzard shad, “an important forage species,” but the testing changed their minds, the department indicated in a news release.
About 165 fish, consisting of bluegill, gizzard shad as well as black and white crappie, were collected in March and early April and have been tested so far. Thirty-one of the 33 pools of five fish each tested positive for viral hemorrhagic septicemia virus or VHSv, a department official said.
“This event is considered an unusually large fish kill but is smaller than an earlier VHSv-related fish kill in 2006,” the DNR said in a news release. “The reasons for the fish kill occurring this year are under investigation, and the mortalities should begin to be reduced with water temperatures rising above 60 to 65 degrees Fahrenheit.”
Many fish recover from the virus, but there is no cure for it, officials said.
The DNR suspected the contagious pathogen was the cause in April because many fish had bloody patches on the skin, which is caused when the fish’s blood vessels leak. The virus is not native to Michigan and is thought to have arrived in the Great Lakes region during the 2000s, the department said
“Ten gizzard shad were tested individually and all were positive for the virus, said Gary Whelan, research program manager for the DNR’s Fisheries Division, in a statement. “These results confirm what we initially suspected: Given the external signs on the fish, species involved, and timing of the fish kill, all strongly implicating VHSv as the cause of this fish kill.”
The DNR said the fish kill is suspected of ranging from Algonac on the northeast shore of Lake St. Clair to Lake Erie. Many of the reports came from Harrison Township to St. Clair Shoes, according to the department.
Anglers should not move live fish from either lake to another body of water to help stop the spread of the virus, the DNR said. They should also properly dispose of bait.
Boaters should ensure their live wells and bilges are emptied before leaving a boat launch, and equipment should be cleaned and disinfected after use, according to the DNR.
The virus has in the past affected more than 30 species of the Great Lakes fish and has been found in lakes Superior, Huron, Erie and Ontario as well as some inland lakes.
“The public has been essential in helping the DNR efficiently track and sample this event and is encouraged to continue to provide us with reports of fish kills with a focus on kills of more than 25 fish,” Whelan said.
The public can still report fish kills to the department’s email, Whelan said. Angler should be part of the team that prevents this virus from spreading to other waters,” he said.