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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

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April 2003

Protecting the bays, streams and Everglades of the north

Nancy Larson & Karen Plass

A positive imprint

Exotic species

Chequamegon Bay, adjoining Ashland and Washburn, covers 53 square miles with an average depth of 28 feet, and maximum depth of 61 feet. Its watershed, fed by more than 2,100 miles of streams, covers 1,440 square miles, making it the largest single watershed on Lake Superior's South Shore. Coastal wetlands ring the bay at the mouths of several streams, notably Fish Creek Sloughs near Ashland, and the Sioux and Onion rivers between Ashland and Bayfield.

The 16,000-acre Kakagon and Bad River sloughs on the Bad River Indian Reservation form the largest undeveloped coastal wetland complex on the upper Great Lakes. These "Everglades of the North," the only remaining location where wild rice is abundant on Lake Superior, produce nearly 20,000 pounds of rice each year. The U.S. Department of the Interior designated Kakagon Sloughs, as a national landmark because it is home to many threatened and endangered species such as the trumpeter swan, yellow rail, bald eagle and wood turtle.

The U.S. Fish and Wildlife Service, which created the 540-acre Whittlesey Creek National Wildlife Refuge in 1999, is working with local landowners to protect and restore another 1,240 acres. Studies of Whittlesey Creek, Fish Creek and other streams are helping resource management agencies understand the unique characteristics of red clay streams and understand how (and how much) land uses have accelerated streambank erosion and sand deposition in streambeds.

The Northern Great Lakes Visitors Center in Ashland. © Karen Plass
The Northern Great Lakes Visitors Center in Ashland.

© Karen Plass

The Northern Great Lakes Regional Visitor center opened near Whittlesey Creek in 1998. The Center offers environmental education programs to address critical natural resource issues in the Lake Superior basin.

A positive imprint

The good work being done in Wisconsin is just part of work being done by agencies and organizations all around the basin. Lake Superior has many moods, many colors, many friends. Its renowned size, awesome power and striking beauty impress those who visit the lake. Those lucky enough to live near it resist leaving, although the economy usually seems greener elsewhere. The challenge is to do as little harm and as much good as possible: to recognize and preserve the things that sustain this remarkably intact ecosystem, and to restore key environmental functions that have been damaged by human activities. Our best hope is to learn to coexist with the lake and its watershed, so future generations will inherit Lake Superior in all its glory.

Exotic species
One cost of shipping is that vessels unintentionally transport exotic (non-native) species in ballast water tanks. These exotics spread to new locations when ballast water is discharged. Several of these exotic species from distant parts of the world now call Lake Superior home, including the ruffe, round goby, zebra mussel and spiny water flea (a tiny crustacean). Nearly 70 percent of ballast water discharges on the Great Lakes occur on Lake Superior, many in Duluth and Superior.

Of the many exotic species in the Great Lakes, the sea lamprey, which entered the Great Lakes through shipping canals, poses the greatest fishery threat. Now controlled at about 10 percent of their all-time high, must continue for the Great Lakes fisheries to survive.

Sea lamprey attach to fish using their sucking-disk mouth. Their toothed tongues rasp a hole in fish and they feed on body fluids. Growing as long as a 17 inch garden hose, adult sea lamprey can live 12 to 20 months and consume 30 to 40 pounds of fish.

The sea lamprey population exploded in the early 1950s, decimating Lake Superior's lake trout harvest, which dropped from 1,813 metric tons in 1953 to 188 in 1961. During the 1950s, control included electrical barriers and then the chemical TFM (3-trifluoromethyl-4-nitrophenol), which kills larval sea lamprey in streambeds. The chemical cut sea lamprey catches on Lake Superior from a record high of 50,975 in 1961 to 7,303 in 1962. Chemical treatment can be effective in all but the largest rivers, but is labor intensive, expensive, and can harm desirable species.

Wisconsin's Bois Brule River, a renowned trout stream, is also a great sea lamprey producer. Between 1973 and 1978, 30 to 50 percent of all sea lamprey captured on U.S. tributaries to Lake Superior were caught there.

As an alternative to chemical treatment, barriers were constructed in the 1980s to keep sea lamprey out of two Wisconsin tributaries: the Bois Brule and Middle rivers.

A low-head lamprey barrier was also constructed on the Iron River in 2001, during removal of the Orienta Dam. The Brule barrier includes a fish ladder with an underwater viewing window. In 1986, its first year of operation, 7,017 sea lamprey (2,142 in one day!) were trapped and removed from the Brule.

Nancy Larson is Wisconsin DNR's Lake Superior program coordinator. Karen Plass is a former Lake Superior specialist with the Wisconsin DNR and former executive director of the St. Louis River Citizens Action Committee; she currently works for the University of Minnesota-Duluth.