Boaters and commercial shippers will be prohibited from emptying ballast tanks within Isle Royale National Park in Lake Superior unless the ballast water is treated to kill invasive species, officials in Michigan said Monday, September 17. Aside from recreational boaters, the new rule will mostly affect Canadian and other foreign freighters calling at the port of Thunder Bay, Ontario.
The emergency regulation is designed to protect the park's fish populations from a deadly virus spreading rapidly across the other Great Lakes, Phyllis Green, superintendent of Isle Royale. Viral hemorrhagic septicemia, or VHS, is among many exotic species that scientists believe have been scooped into ships' ballast tanks in foreign ports, then discharged into the Great Lakes. VHS has not shown up in Lake Superior, but has caused large die-offs of popular game species such as walleye, northern pike and yellow perch in the other lakes and some inland waterways.
The rule will affect Canadian and other commercial ships because the shipping lane between Thunder Bay and the Soo Locks, gateway to Lake Superior, runs through Isle Royale waters, Green said. Nearly all those ships are Canadian or based in other foreign countries, said Glen Nekvasil, spokesman for the Lake Carriers Association, which represents U.S.-flagged freighters that remain inside the Great Lakes system.
Green said lake trout around Isle Royale were especially vulnerable, especially this time of year, when they are congregating to spawn and can spread disease quickly between them. Her order, which takes effect Tuesday, September 18, covers a 684-square-mile (1,772-square- kilometer) area, including 475 square miles (1,230-square-kilometers) of waters within park jurisdiction. Isle Royale is in northwestern Lake Superior.