Mercury contamination in Lake St. Clair and western Lake Erie forced Ontario officials to ban commercial fishing in these lakes, protecting consumers from dangerous fish but crippling the livelihoods of professional fishers.
On March 19, 1970, the findings of scientist Norvald Fimreite’s research on mercury contamination
In early 1969, Norvald Fimreite had projected that mercury-contaminated fish would be found in the waterways of Ontario and Quebec. He based his projections on the fact that several chlor-alkali manufacturing operations were located in these provinces, and he estimated that about one half-pound of mercury was discharged into the waterway by each plant for every ton of chlorine produced, or approximately 200,000 pounds of mercury per year. Fimreite’s conclusions were substantiated in Ontario when the Water Resources Commission surveyed mercury losses from pulp and paper mills as well as chlor-alkali plants. The commission found that six chlor-alkali plants resupplied their mercury cathode cells with 264,000 pounds of mercury per year and eight pulp and paper mills consumed 48,000 pounds of mercury per year. Even assuming that about half of this amount was recycled, more than 150,000 pounds of mercury were being released to Ontario’s watercourses annually from these sources alone.
In the fall of 1969, both Fimreite and George A. Kerr
Later, in 1970, when Dow Chemical Company’s vice-president, C. B. Branch, testified at a hearing before the U.S. Senate Subcommittee on Energy, Natural Resources, and the Environment
Once discharged from the plants in a solute form, the mercury was rapidly transformed by reduction to metallic mercury. A high percentage of this form was incorporated in the silty bottom sediments of Lake St. Clair and western Lake Erie along with other mercury particulates. In the surface layers of the sediment, complexing of the mercury took place. Microorganisms dwelling in the sediment initiated the conversion processes into methylmercury compounds. These compounds entered the food chain and accumulated in fish and other aquatic organisms. Organic mercury compounds such as these pass easily through membranes and are concentrated in fish until a lethal dose is reached or the animal is incapacitated and dies of starvation. Mercury in fish tissue is easily transmitted to humans when contaminated fish are eaten.
Prior to the discovery of mercury in the lower Great Lakes, the worst case of mercury pollution was in the 1950’s at Minamata
On April 2, 1970, the American Embassy at Ottawa informed the U.S. secretary of state about the mercury problem, but by then federal, state, and provincial officials on both sides of the border were already feverishly studying mercury contamination, and the newspapers screamed for action. When the mercury levels in fish taken from Lake St. Clair were first publicized, however, some U.S. government officials believed that there was no imminent danger. Russell Scholl, fishery management supervisor of the Ohio Division of Wildlife’s Lake Erie office, pointed out that the Americans were not finding mercury in the environment because they were not looking for it. Belatedly, the U.S. Food and Drug Administration
Both Canada and the United States had zero tolerance levels for mercury in food prior to this incident. The U.S. Food and Drug Administration had ruled that mercury was an unintentional food additive. If this ruling was strictly followed, all fish with any mercury residues, in other words, all fish, could have been seized. Instead, the United States followed Canada’s example and both countries quickly adopted an interim 0.5-part per million (ppm) “action” guideline. Fish that exceeded the guideline for mercury residues would be seized and destroyed. At the same time, no fishing would be permitted in lakes and streams where fish consistently registered above the 0.5-ppm guideline.
This guideline was established based on the research conducted by the Japanese at Minamata Bay and was justified on the grounds that the Japanese consumed up to seven ounces of fish per day (five times the American daily average of about one and one-half ounces). The North American eating habits and the contamination levels of the fish were thought to provide a tenfold safety margin. Moreover, fish from Lake St. Clair averaged around 2.5 ppm, only 25 percent of the Japanese average. The U.S. Food and Drug Administration safety margin, however, was clearly based on averages rather than on possibilities, because some of the Lake St. Clair fish tested as high as 7.0 ppm, and people with access to fisheries often consume considerably more than the national average. The Canadians also justified their 0.5-ppm guideline on the basis of average fish consumption instead of on the dietary habits of minorities, such as the Walpole Indians who lived on a reserve on the delta of the St. Clair River, or the Ojibway Indians who lived on reserves adjacent to contaminated rivers.
The rising mercury levels in fish seemed to be of less consequence as a health problem when the awesome economic implications of the action guidelines became more apparent. Commercial fishing of Lake Erie walleye and yellow perch was banned because these fish were determined to exceed the 0.5-ppm action level. As one state after another (Michigan, Ohio, and New York) followed Canada’s lead, fish sales plummeted throughout the Midwest, and the Lake Erie and Lake St. Clair commercial fisheries became economic disaster areas. Within two months of the commercial fishing ban on Lake St. Clair, the government had loaned the fisherman more than $100,000. No indication was given to the fishers as to when they would be able to fish again. The sport-fishing business also slumped when the fishers themselves heeded public warnings not to eat the fish. Canadians and Americans were faced with enormous economic losses as long as the ban continued.
The cost to the sportfishing industry tallied into millions of dollars on each side of the border. In Michigan, Governor William G. Milliken’s decision to ban all fishing in the U.S. waters of Lake St. Clair and the St. Clair River aroused the ire of sports enthusiasts. In the Detroit area, the fishing ban put a damper on numerous tourist camps, boat rentals, and bait shops. In previous years, Lake St. Clair had supported more than 200,000 angler-days of fishing per year. Thus, the mercury contamination destroyed a sportfishing industry with an estimated potential gross value of $15 million. Moreover, the facilities and equipment that supported sport and commercial fishing were then estimated to be worth up to $400 million. Faced with such enormous financial losses from sportfishing revenues, Ontario officials instituted a “fish for fun” policy, and the Americans followed with an equivalent “catch-and-release” program. Although these plans were publicized before the normally crowded Memorial Day Weekend, participation declined dramatically from earlier years.
In 1970, the Dow Chemical Company announced a crash cleanup program to reduce mercury discharges. At about the same time, it was determined that another chlor-alkali plant, located in Wyandotte, Michigan, on the Detroit River (BASF Wyandotte Corporation
By 1974, mercury levels had declined to the point that sport-fishing advisories were lifted on Lake St. Clair and Lake Erie. Ontario also allowed limited commercial landings in 1974, but Michigan and Ohio continued to prohibit commercial fishing for walleye in favor of the sport-angling fishery. Starting in 1970, however, an unexpected benefit to the fishery emerged as a result of the walleye ban. The western half of Lake Erie long sustained the best walleye fishery in the Great Lakes, if not in the world. Commercial harvest was relatively stable at about one thousand tons per year from 1885 to 1939. Walleye catches then increased steadily to a peak of seven thousand tons in 1956, but precipitously dropped to about two hundred tons in 1969.
Following the institution of the commercial fish ban, the walleye population recovered remarkably. It appears that the walleye population had been depleted by overfishing and stressed by environmental factors. A complete collapse of the walleye stock was barely averted by the moratorium on commercial fishing. In 1972, Canada and the United States signed the Great Lakes Water Quality Agreement
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Adams, G. F., and D. P. Kolenosky. Out of the Water: Ontario’s Freshwater Fish Industry. Toronto: Ontario Ministry of Natural Resources, 1974. Presents a historical overview of Canadian commercial fishing on the Great Lakes, including the tragic closure of the Lake St. Clair fishery as a result of mercury poisoning. The characteristics of Great Lakes fish species and fishing techniques are described in nontechnical language. -
Barry, James P. The Fate of the Lakes: A Portrait of the Great Lakes. Grand Rapids, Mich.: Baker Book House, 1972. This abundantly illustrated book documents the vital ecological concerns faced by Canada and the United States in managing the Great Lakes. Pollution problems such as untreated sewage, mercury contamination in fish, nutrient enrichment, and oxygen depletion are discussed for Lake Erie. -
Bligh, E. G. “Mercury Levels in Canadian Fish.” In Mercury in Man’s Environment. Ottawa, Ont.: Royal Society of Canada, 1971. Documents the level of methylmercury found in fish from Lake St. Clair and Lake Erie as well as other portions of the Great Lakes. This volume also contains articles on the sources of mercury contamination. -
Bolsenga, Stanley J., and Charles E. Herdendorf. Lake Erie and Lake St. Clair Handbook. Detroit, Mich.: Wayne State University Press, 1993. This highly illustrated book describes the conditions, processes, and natural features of the coastal and offshore waters of Lake Erie and Lake St. Clair. Presents a comprehensive view of environmental quality, including a discussion of mercury as a pollutant of lake sediment and in the food web. -
Burns, Noel M. Erie: The Lake That Survived. Totowa, N.J.: Rowman & Allanheld, 1985. A semitechnical book that embodies a blend of scientific and human concerns about Lake Erie, one of the worst cases of environmental degradation. The circumstances of heavy metal contamination and associated impacts on fish populations are reviewed. -
D’itri, Patricia A., and Frank M. D’itri. Mercury Contamination: A Human Tragedy. New York: John Wiley & Sons, 1977. Contains a series of case studies on mercury pollution, including the contamination of Lake St. Clair and Lake Erie, which resulted in a ban on the sale of fish caught in these lakes. This nontechnical book deals with the use of mercury and the environmental degradation associated with its abuse. -
Fortner, Rosanne W., and Victor J. Mayer, eds. The Great Lake Erie. Columbus: Ohio State University Research Foundation, 1993. Designed as a reference text for educators. Contains chapters on lake shipping, effects of human activities on the lake ecology, changes in the lake fishery, recovery from phosphorus enrichment, and toxins in the lake. -
McGucken, William. Lake Erie Rehabilitated: Controlling Cultural Eutrophication, 1960’s-1990’s. Akron, Ohio: University of Akron Press, 2000. Study of the eutrophication of Lake Erie and the Canadian and American response to that eutrophication. Bibliographic references and index.
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