VHS threatens Oakland County inland lakes

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Fish infected with Viral Hemor...

OAKLAND COUNTY, Michigan - Viral Hemorrhagic Septicemia was first noted in Michigan’s Great Lakes six years ago. Since then, the virus has killed many species of fish in several other Michigan lakes and rivers including Lake Erie, the Detroit River, Lake St. Clair, Lake Huron, Lake Ontario, and the St. Lawrence River.

While the Michigan Department of Natural Resources – Fisheries Division continues to manage a number of fish diseases including the VHS virus, Michigan’s ailing economy is having a direct impact on the department’s resources and its ability to do so. As a result, Oakland County lakefront owners, anglers and conservationists are worried that the disease may spread to some of Michigan’s inland lakes.

The earliest confirmed report of VHS came in 2003 when an angler caught a muskie from Lake St. Clair. It isn’t really known how the virus landed in the Great Lakes, but ballast water discharge is considered to be the most likely cause.

Infected fish shed the virus in their urine and reproductive fluids. The virus can survive in water for at least 14 days. Virus particles in the water infect gill tissue first, and then move to the internal organs and the blood vessels. The blood vessels become weak, causing hemorrhages in the internal organs, muscle and skin. Fish can also be infected when they eat an infected fish. Fish that survive the infection will develop antibodies to the virus. Antibodies will protect the fish against new VHS virus infections for some time. However, the concentration of antibodies in the fish will drop over time and the fish may start shedding virus again. This may create a cycle of fish kills that occurs on a regular basis.

A voluntary program though Oakland County was recently presented to all Oakland County governmental agencies, asking all to consider placing disinfection stations at the public access points of their most heavily fished lakes. The goal is to provide anglers the necessary environmentally-friendly chemical to disinfect and eliminate VHS and other pathogens from their water craft before launching into another lake.

The matter came up during a June 9 Holly Village Council meeting where council decided to forego the chemical station, and opted instead to erect a warning sign about the disease, and to provide anglers with informational flyers about the virus.

In the event that a disinfection station is not available, anglers are asked to take responsibility for disinfecting their own equipment prior to launching onto a public lake.
The DNR recommends that all aquatic plants, animals and mud be removed from the boat and trailer. Water from the motor, live well and bilge should be drained, and unwanted bait should be discarded in the trash. Using a mixture of five gallons of water and 1/3 cup of bleach, the boat should be sprayed or scrubbed with the solution, and left wet for ten minutes before rinsing.  Rinsing is best done over gravel and way from the lake.

So far, those Michigan fish affected by the virus include muskie, small mouth, white and rock bass, northern pike, freshwater drum, gizzard shad, yellow perch, black crappie, blue gill, redhorse and blunt nose suckers, round goby and walleye.

While some infected fish won’t show any external signs of the virus, others may have bloated abdomens, bulging eyes, inactive or overactive behavior and hemorrhaging in the eyes, skin, gills and at the base of the fins. Internally, one would find that the organs of an infected fish may have multiple hemorrhages, specifically in the liver, spleen and intestines.

Humans cannot catch the virus as VHS isn’t a human pathogen and is unable to replicate in warm bodied animals. There are absolutely no concerns with respect to human health, and humans will not become infected if they eat a fish that is infected with the virus.

Those who suspect that they may have caught a sick fish should contact the local DNR office or use the DNR web site (www.michigan.gov/dnr) to report it.