The Death and Life of the Great Lakes

by Dan Egan

these ships typically bring in foreign steel and haul out U.S. and Canadian grain.

The Great Lakes are now home to 186 nonnative species. None has been more devastating than the Junior Mint–sized zebra and quagga mussels, two closely related mollusks native to the Black and Caspian Seas.

The mussels, which have no worthy natural predators in North America, have transformed the lakes into some of the clearest freshwater on the planet. But this is not the sign of a healthy lake; it’s the sign of a lake having the life sucked out of it.

Like generations of the past, we know the damage we are doing to the lakes, and we know how to begin to stop it; unlike generations of the past, we aren’t doing it.

Like the plugs of land that once isolated the basins that are now the Mediterranean and Black Seas, erosion has been having its way with Niagara Falls. It is expected the falls will disappear in about 50,000 years—which is to say, geologically speaking, pretty soon. When that happens, the cliffs that have for millennia separated the upper Great Lakes from the Eastern Seaboard will be gone. All that will remain is a fast-flowing, ever-eroding riverbed that will draw the lakes, every day, one step closer to sea level.

the falls that tumble over the Niagara escarpment near present-day Buffalo, New York, are nowhere near the world’s tallest or even largest by volume. But they were among the most ecologically important because they created an impassable barrier for fish and other aquatic life trying to migrate upstream from Lake Ontario into the other four Great Lakes.

Other giant freshwater bodies that have evolved over tens of thousands or even millions of years have been subjected to epic changes in temperature, salinity, water levels as well as wave upon wave of invading and evolving organisms, all in a manner that leaves those water bodies inhabited by a cast of species steeled by the crucible of evolution. This gives them something of an “immune system” when it comes to maintaining ecological stability in the face of disruptions from the outside world. The Great Lakes of Cartier’s time, on the other hand, were what biologists today call “ecologically naïve.” This means the lakes were inhabited by fish and other aquatic species whose isolation left them uniquely exposed to foreign perturbances. None of this, of course, was pondered by the early explorers desperate to exploit their ecological bounty.

THEY MIGHT BE CALLED THE GREAT LAKES, BUT THE FIVE INLAND seas are essentially one giant, slow-motion river flowing west-to-east, with each lake dumping like a bucket into the next until all the water is gathered in the St. Lawrence River and tumbles seaward.

Lake Superior sits at the system’s headwaters. It is about 350 miles long and 160 miles wide, and it holds enough water to submerge a landmass about the size of North and South America under a foot of water.

A single Seaway ship can hold up to six million gallons of vessel-steadying ballast water that gets discharged at a port in exchange for cargo. And that water, scientists would learn after it was too late, can be teeming with millions, if not billions, of living organisms.

If their food supply hits a low cycle, lake trout simply throttle down their metabolism and stop growing as they wait out the lean years. Were a trout to let its guard down in this fashion in the ocean, a bigger fish likely would swallow it whole. But adult lake trout in the Great Lakes food web only had to worry mostly about eating, not being eaten. This ability to pace its growth with available food sources made it the perfect fish to regulate—or, more accurately, harvest—the slow flow of energy through the Great Lakes that starts 93 million miles away.

In Lake Michigan alone some biologists believe the fish were organized into at least 100 stocks, many of which became isolated populations that bred only among themselves. Across the Great Lakes, each stock became uniquely adapted to thrive in the areas it colonized.

In Lake Michigan alone the annual lake trout commercial harvest in 1944 was still nearly 6.5 million pounds. Five years later it had dropped to 342,000 pounds, and five years after that, it was zero.

When water from that feeder canal coursed into the Welland Canal at the crest, it then flowed in two directions in the Welland—south toward Erie and north toward Ontario. So a lamprey, nature-built to always swim upstream, would have sensed the downstream switch in current at the crest and headed into the feeder canal and, the theory goes, likely would have ended up in a tangle of upland streams and soggy ditches draining agriculture lands—a biological dead end and, if the story ended there, a life saver for fish in the upper Great Lakes.

Applegate learned that spawning lamprey preferred streams with bottoms peppered with gravel that had a diameter no smaller than three-eighths of an inch and no bigger than two inches, and that they typically did not migrate up those streams until early spring, when the water temperature rose above 40 degrees.

1967 researchers figured they were well on their way to pushing the Great Lakes’ lamprey population down to about 10 percent of its peak, where it remains today due to a nonstop poisoning program that costs about $20 million annually.

in Lake Ontario the East Coast fish lived for a few years in harmony, if not obscurity, with the native fish. A likely reason is the big lake’s predators—Atlantic salmon and lake trout—would have been able to keep them in check. But when commercial overharvests destroyed the populations of those big fish, the now-landlocked river herring began to appear in the 20th century in “almost incredible” numbers, in the not-so-scientific words of Robert Rush Miller, a biologist at the University of Michigan.

The result can only be described as an ecological meltdown—particularly on Lake Michigan—previously unmatched in scope or speed. By 1962, biologists estimated the river herring accounted for 17 percent of the fish mass in Lake Michigan. Three years later that number was pegged at 90 percent. The exotic herring had similar success in Lakes Huron and Ontario, and took hold to a lesser degree in the colder and more sterile Lake Superior, and the warmer and more predator-filled Lake Erie.

Muskegon and South Haven.

Visited; summer 2019

By the middle of the summer newspapers were estimating that the total cleanup cost on Lake Michigan would reach $50 million—$350 million in today’s dollars. The impact spread beyond Chicago. Fish piled up on beaches all across southern Lake Michigan that summer, costing the tourism industry an additional $55 million—again, in 1967 dollars, making this all the better part of what would be a billion dollar problem today.

Some commercial fishermen tried to make a dollar off the alewives by catching them for two pennies per pound, hauling ashore some 40 million pounds of them on Lake Michigan alone that summer of 1967. Food scientists of the era were scrambling to figure out how to turn that flesh into a digestible—if not marketable—form of human food. They explored alewife fish sticks, alewife breakfast sausages and even mixing the alewife flesh into bread dough, molding it into loaves and baking it in industrial ovens. None of that panned out. The only market for the fish was to churn them into cat food, turn them into liquid fertilizer or convert them into fur coats—much of the haul was sold as feed to Midwest mink farms.

The real problem, it turned out, was the alewives themselves. The Great Lakes version of the fish grows only about six skinny inches in length, compared to a fat foot or longer for their ocean cousins. Great Lakes alewives’ kidneys are under immense stress because, not being a true freshwater species, the fish are forced to constantly urinate to expel the freshwater persistently seeping into their cells. At the same time, their bodies are working overtime to retain what precious salts they can pull out of the freshwater. Great Lakes alewives also have a stunted thyroid, likely due to a deficit of iodine in freshwater. This may further prime them for death when the real trouble hits: water temperature swings unlike anything the species had to deal with in the ocean.

“The salmon weren’t put here to feed people,” said Great Lakes fishery historian Kristin M. Szylvian, “as much as to amuse them.” The salmon were basically declared off-limits to commercial fishermen and, therefore, off-limits to grocery shoppers or restaurant diners. They became the property of the sportsmen who bought the fishing licenses that funded the salmon-planting program, a program that would prove to be a boon for tourism but also, ultimately, an obstacle in efforts to restore some semblance of natural order to the lakes in the decades after the lamprey infestation.

After high school Tanner was pulled away from the guide business to get an education. “I turned 18 and started college at Western Michigan University, where my mother and her sisters and brothers had all gone to school,” Tanner, who described himself as an unfocused scholar at that point,

Kalamazoo

biologists started digging into the salmon flesh and learned it was packed with the pesticide DDT in concentrations as high as 19 parts per million, more than three times the federal limit of 5 parts per million.

“We find that cooking them gets rid of most of the oil—which contains the DDT—and gets them down well below the five parts per million,” he said. “And they taste damn good.”

A big reason for the crash is that the salmon began breeding in the wild at unsustainable numbers—there were simply too many chinook mouths and not enough alewife tails.

Although Lakes Michigan and Huron are actually one giant body of water they are in many ways distinct. Lake Michigan is a more “productive” lake due to the nutrients flowing from its tributaries that yield more alewife-sustaining plankton.

Ohio law at the time gave state regulators supremacy over water pollution enforcement, and since the factories and mills along the river had received discharge permits from the state, no matter how weak they were, the city maintained it was powerless to force those businesses to change their polluting ways. The state, meanwhile, threatened “drastic enforcement measures” against the city of Cleveland, absurdly claiming the fire was fueled by oily runoff from city streets and leaky sewers.

A U.S. Steel spokesman said he simply did not see the problem as his. “To the best of our knowledge,” he said, “we are in complete conformity with all existing federal and state codes relating to water quality in the Cuyahoga River.” Nobody was fined a dime. In 1972, Congress overrode a President Nixon veto and approved a sweeping package of amendments to the existing federal water pollution regulations that are known today as the Clean Water Act. This turned the tables by establishing the principle that industry does not have a “right” to pollute and must therefore apply for a permit to do so.

Under some conditions the plankton-feasting mussels can now “filter” all of Lake Michigan in less than two weeks, sucking up the life that is the base of the food web and making its waters some of the clearest freshwater in the world.

One study on southeastern Lake Michigan revealed that by 2009, phytoplankton levels in springtime—the prime plankton-growing time of year—had dropped nearly 90 percent since the mussels took over the lake bottom. It’s probably not a coincidence that the lake’s fish populations have dropped at the same time.

The mussels have provided all three. Their plankton-stripping ability has dramatically increased the depths to which sunlight can penetrate. Their shells provide a surface on which the seaweed can grow and the mussels’ phosphorus-rich excrement fuels the plant’s growth. The result is an endless forest of brilliantly green, hair-like tendrils swaying in the current, invisible to anyone on shore—until relatively small amounts of it break off, wash ashore and, along with the mussels it has attached to, rot.

Invasive mussels have increased water clarity. That has led to a bloom in the sunlight-loving Cladophora that eventually dies and burns up massive amounts of oxygen as it decomposes on the lake bottom. That has opened the door to botulism-causing bacteria that thrive in oxygen-starved environments. The invasive mussels, many biologists believe, suck up those bacteria and are, in turn, eaten by gobies. The poisoned gobies become paralyzed and are easy prey for birds like loons, grebes and gulls. The birds die.