Commercial and sport fishing are very important to the economies of Wisconsin and the Great Lakes region. The Great Lakes fishery is collectively valued at more than $4 billion annually, despite the following problems that have degraded the fishery over the past 100 years.

Water Pollution

The Great Lakes fisheries have suffered from several water quality problems, including persistent toxic substances such as PCBs, mercury and chlorinated organic pesticides, and excess nutrients such as phosphorus and nitrogen. The toxins result in fish consumption advisories throughout the region, and the nutrients cause large increases in algae, which foul near shore areas and alter the food chain. According to Dr. Jeffery Foran, toxicologist,"Those who eat fish from lower Green Bay and below the DePere Dam face a cancer risk due to PCBs equal to smoking 2 to 3 packs of cigarettes a day."In some waters, fish are suffering from tumors, abnormal livers and thyroid glands, and reproductive abnormalities.

On the Fox River and Green Bay, walleye tumors are promoted by the presence of PCBs. Recent studies indicate that certain fish, such as lake trout, may have gone extinct in some of the Great Lakes because of dioxin and PCB contamination, which injures or kills newly hatched trout fry. More than a dozen species of native fish (chubs, herring, etc.) have become extinct on Lake Michigan alone, which may also be partly linked to this toxic effect.  Lake trout stocking has countered some of this loss, but at great expense.

Wetland Losses

More than a century ago, the Bay of Green Bay was considered one of the top three commercial fisheries in the Great Lakes (along with the west end of Lake Erie and Saginaw Bay) because it was so productive. Hundreds of commercial fishing companies and fish processing houses operated on the bay shores. Much of that productivity was due to the extensive marshlands of southern Green Bay. Scientists consider the bay to be the largest freshwater estuary in the United States. The bay water levels fluctuate due to a tide-like "seich" (pronounced "saysh") created by wind pressures on the bay. Seiches push the bay water into the marshes, then drain back out, creating a very active and fertile zone of fish habitat. Because more than 90% of the wetlands have been filled in southern Green Bay, much of this productivity has been lost.

Invasive Species

The Great Lakes are plagued with a wide variety of introduced or escaped wildlife from other parts of the world. Some of these have become major pests, upsetting the ecological stability of the Lakes system and damaging the fishery. These include: Carp, zebra mussels, spiny water flea, white perch, phragmites, alewives, and sea lamprey. Once they invade, it's impossible to exterminate them, so fisheries managers are forced to adapt. Sea lamprey can be somewhat controlled by treating Great Lakes tributaries with a specific lampricide chemical, but for many other species no control measures are available.

Excessive Harvests

Prior to management efforts, the Great Lakes fisheries were over-harvested, with the greatest commercial fishing harvests recorded in 1889 and 1899 at about 147 million pounds. Excessive harvests have occurred periodically until recent years, when harvest quotas have been imposed on commercial fishing businesses, and creel limits have been set for sport anglers.

Fishing Links

Fisheries Management - Wisconsin Dept. of Natural Resources -

Wisconsin Fishing Clubs and Associations -

Wisconsin Fishing Guides and Charters -

Hunt,Fish,Camp Wisconsin -

© Clean Water Action Council

P.O. Box 9144

Green Bay, WI 54308

(920) 421-8885

Office location:
A307 MAC Hall, UW-Green Bay
2420 Nicolet Drive
Green Bay, WI 54311