Whitefish sit in a large plastic bin waiting to be processed at the Bay Port Fish Company in Bay Port, Michigan on Wednesday, May 4, 2022. Eric Seals, Detroit Free Press

After the Williams family purchased the Bay Port Fish Company in 1978, they would take their boats out to Saginaw Bay and Lake Huron to catch carp, catfish and yellow perch. Decades later, they still hold a license for 44 nets to catch yellow perch but have not used it for at least two years.

“There just isn’t much yellow perch left on our side of the bay,” said Lakon Williams, who took over the management of the family business 10 years ago. “Why would I want to hurt the population more and set 44 nets out there?” 

Over the years the Williams family, one of the few remaining commercial fishers in Michigan, invested in new equipment for harvesting whitefish, a higher value catch whose stocks were rebounding after a sharp drop in the mid-1900s. Since the turn of the century, however, whitefish harvests have dwindled. For the business to survive, Lakon added processing and resale to their fishing operations, purchasing the catch from other fisheries and shifting most of their business into retail and distribution.

“In the ’80s all we had to do was to dip them out of the tanks and put them into people’s coolers,” she said. “We had to add a lot of value to stay relevant.”

The story of the Bay Port Fish company is only one in the millions of lives, built on the shores of the Great Lakes — the largest freshwater lake system in the world. More than 34 million people now live in the Great Lakes basin — a complex, ever-changing environment that includes parts of eight U.S. states — Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania and Wisconsin — and the province of Ontario in Canada. Over the last few centuries the region has had to endure a number of environmental stresses: industrialization and deforestation, growth of large-scale agriculture and overfishing, disruptive infrastructure projects and waves of invasive species. 

Climate change brings a new and accelerating challenge to the region. According to the Great Lakes Integrated Sciences and Assessments program, from 1951 to 2017:

GLISA is a collaboration between Michigan State University and the University of Michigan, supported by the National Oceanic and Atmospheric Administration.

In most areas the ice season has gotten shorter and summer surface water temperature has increased at a higher rate than the surrounding air temperature. According to a 2019 report by the Environmental Law and Policy Center, the Great Lakes region has been warming faster than the rest of the contiguous United States.

The Great Lakes are experiencing yet another transformation, and the warming climate is having an indelible effect on the nearly two hundred known species of fish living in these waters in ways that are not yet fully understood. The changes impact where Great Lakes fish can live, what they can eat, where they lay their eggs and how well their young survive. It also can open the door for more invasive species that out-compete native species and other, desired fish stocks.

With the Great Lakes fishery estimated to be worth more than $7 billion to the region annually, recognizing the ways in which the local fisheries are changing is a matter of great concern to environment biologists, fishery managers, state treasurers, and pretty much anyone who likes to spend a weekend with a fishing rod and bring home some fresh catch.

In her book “Fishing the Great Lakes : An Environmental History, 1783–1933” Margaret Beattie Bogue tells about Father Claude Dablon, a Jesuit missionary who provided one of the earliest written accounts of traveling through this immense expanse of water and the surrounding lands. Entering Lake Ontario in 1655, he wrote, “Such a scene of awe inspiring beauty I have never beheld, nothing but islands and huge masses of rock, as large as cities, all covered with cedars and firs." One of a number of proselytizing monks who followed the fur traders into this sparsely populated expanse, he witnessed the Ojibwe hoop-net fishing in the rapids of the St. Marys River, catching the plentiful whitefish. 

Those fishermen followed in the tradition of generations of Native Americans, who have fished the Great Lakes for millennia before European settlers arrived. Completion of the Erie Canal in 1825 sped up the arrival of migrants and stimulated industrial development, logging, agriculture and large-scale commercial fishing. The effect on the environment was enormous, prompting the rise of the contemporary environmental movement and attempts at regulating natural resource exploitation.

As early as 1801, New York State passed the first measure designed to protect the salmon fishery, prohibiting the use of obstructions and building dams on designated rivers and streams flowing into Lake Ontario. Throughout the nineteenth century, laws were passed in Ohio, Michigan, Wisconsin and Canada, attempting to address the issues of overfishing and contamination, Bogue writes, but the overwhelming pressure from commercial interests and lack of public engagement made them largely ineffective. Atlantic salmon disappeared from the Great Lakes before the 20th century.

Rapid industrialization, growth of agriculture and logging, invasive species and habitat loss caused by urban development have dealt serious blows to the ecology of the lakes. The low point, arguably, came toward the 1950s and 60s, when piles of dead and rotting alewife would stretch for miles along the beaches, and tributaries were so polluted they occasionally caught on fire. Lake Erie was briefly pronounced dead because of an overload of phosphorus from municipal waste. 

Environmental movements of the 1960s ignited public concern about the deterioration of water quality, stimulating new investment into research and management of the Great Lakes watershed. This concern was formalized in the first Great Lakes Water Quality Agreement between Canada and the U.S. in 1972 and led to a number of concerted efforts to address environmental issues, including failing fish populations. 

Thanks to stronger environmental legislation and investment into restorative projects, the last 50 years have seen large-scale efforts to overturn two centuries of damage to the Great Lakes. Popular sporting fish such as the Pacific salmon were introduced and many native species have rebounded. Recreational fishing generates $2.3 billion in Michigan alone, according to a 2019 report by the Michigan United Conservation Clubs and the Michigan State University Eli Broad College of Business, while commercial fisheries continue to provide the markets and restaurants with fresh catch. According to Marc Gaden, communications director for the Great Lakes Fisheries Commission, on a very broad scale the lakes are probably in the best shape they’ve been in for 150 years. 

However, climate change poses a threat to the gains made over the last 50 years, Gaden said. It will have an effect on every stressor the lakes are already experiencing, from farm runoff to shoreline erosion, from influencing invasive species habitats to overstressing the thousands of aging dams in the region. It will transform the lakes as we know them, in many ways yet unknown.

One of the native species affected by the warming climate is whitefish — an unassuming, silvery-brown fish native to these waters that has sustained people living on these shores for thousands of years. Adikameg, as it is called in Ojibwe language, has been an important staple to Native American peoples, and over the last two centuries sustained robust commercial fisheries on both sides of the border. 

Whitefish populations had collapsed by the 1950s, then rose throughout the late 20th century, but took a hit again at the start of this century, following the introduction of zebra and quagga mussels, invasive species likely brought to the Great Lakes by large ocean-going ships sometime in the 1980s. Collectively known as dreissenid mussels, they aggressively filter lake waters for plankton and algae, altering the food web, robbing whitefish of the prey they used to rely on. Yet these nutrient-gobbling mollusks quietly transforming the local ecosystem are not the only culprit.

Adult whitefish spawn from October to December on nearshore shoals, preferring rocky lake bottoms, where the eggs then spend the winter before hatching in the spring. Larval fish then move to nearby embayments, hungry for plankton — tiny drifting organisms carried along with tides and currents, whose abundance is critical to their survival. Larvae that grow to become juvenile fish move into deeper colder waters in the summer, where they continue their path to adulthood. This process, by which very young small fish survive to become older, larger fish, is called recruitment.

Whitefish recruitment is largely driven by larval survival, said Mark Ebener, research technician at Michigan State University Department of Fisheries and Wildlife. Ebener edited a number of white papers for the Great Lakes Fishery Commission, including a 2021 report on whitefish. He noted that both harvests and recruitment in all of the lakes except Lake Superior have been falling, and have dropped even more since writing the report. In northern Lake Huron, he said, tribal fishers caught only 125,000 pounds of whitefish in 2020, a precipitous drop from over 2 million pounds in years prior.

It is a long and dangerous journey for a juvenile fish to become an adult, to spawn or to get caught in a fisherman’s net, but it’s nowhere near the rates of mortality for eggs and larvae. A female whitefish can produce from 10,000 to 130,000 eggs in a season, and just a fraction of a percent make it through the first year. If spawning grounds stop consistently adding juveniles to the population chances diminish for the fishery at large to stay healthy. Ebener suggests that managers put increased focus on whitefish reproduction habitat, both physical and biological state of the areas that make up about 2% of the total area of the Great Lakes.

A lot of the scientific work on the effect of climate change on fish recruitment is only now getting started, said Steve Pothoven, a fishery biologist at NOAA Great Lakes Environmental Research Laboratory. It takes five to seven years for whitefish to mature and plenty is still unknown about their life cycle. 

Lake whitefish enjoy cold waters and benefit from long winters and plentiful ice cover. Multiple studies have suggested that ice protects the eggs from the wind and waves or from UV radiation. Other papers notice a link between cold waters and improved embryo growth. Ice cover may also help improve production of zooplankton — microscopic animals that larval whitefish feast on. After a cold winter, Pothoven said he noticed waters warm up fast and larvae seem to eat well, while early springs are often followed by cold snaps that stall their development. 

Ebener has observed similar changes where he lives, on Sugar Island at the outflow of Lake Superior. 

“You don’t get frost anymore in September,” he said. “You hardly get frost in October. But this May has been cold as hell.” 

The climatic cycle looks to have shifted, and these changes have to have some influence on fish reproduction, he said. 

Commercial whitefish harvests across the Great Lakes region had declined 59% from their 1998 peak to 2016, according to data provided by Ebener. In some areas, catch numbers remained flat or rose slightly. In and around Saginaw Bay, where the Williams family plies their trade, the whitefish population has been sustained, with catches dropping only 18%. Overall, however, Lake Huron whitefish harvests have dropped by 69%. The northern Michigan area of Lake Huron has borne the brunt of the decline, dropping by a massive 92%. 

SOURCE Mark Ebener, The Fresh Lake Whitefish, Sault Ste. Marie

Ebener agreed that warming waters are having an effect, however he noted that many spawning sites that no longer get ice in winter are still producing plenty of fish. The primary driver, he said, is the dreissenid mussel invasion, and the dropping amounts of zooplankton caused by it. Climate change effects need to be studied in conjunction with all the other factors transforming ecosystems.

“Any sort of environmental change is gradual,” Pothoven said. “It’s like not noticing the changes in your face. But then you jump back 20 years and see something that’s really different.” 

Weather differences from year to year can sometimes mask long-term changes, he added, but at least in Muskegon, where he lives, most people who fish would say there’s definitely not as much ice as there used to be. 

With high-quality observational data compiled over more than a century by the Climatic Research Unit, the warming trends become clear.

As the air warms, so do the lake waters. According to the US Climate Resilience Kit from climate.gov, summer surface water temperature in Lake Huron increased by 5.2 degrees, and in Lake Superior by 4.5 degrees between 1968 and 2002. That was twice the rate of increase in air temperature. The ice season got shorter by an average of five days every decade from 1974 to 2004 across 65 lakes in the region.

These trends are expected to continue and accelerate, according to the kit, and the rates of change will depend on the amount of heat-trapping gasses like carbon dioxide and methane released into the atmosphere. With a highly energy-intensive economy, per capita emissions of greenhouse gasses more than 20% higher than the national average and a large potential to reduce emissions, the Great Lakes region will continue to have an outsized influence on the global climate. 

there ain’t much to ice fishing till you miss a day or more

“Climate change sucks,” Brian Seiferlein said. 

Seiferlein decided to become an ice fishing guide after the winters of 2014 and 2015, when everyone learned the term “polar vortex.” For two years in a row, a low-pressure system of Arctic air got pushed south into the continental United States, making for some memorable cold seasons.

“That was like the good old days, like when I was a kid,” said Seiferlein, who’s been fishing on Saginaw Bay for over 40 years. Ice on the bay stayed strong for months, and Seiferlein decided to turn his hobby into a business. He bought more equipment and built a website. 

But there haven’t been winters like that since. In 2021, Seiferlein said, they had just nine days of ice fishing in February, then the temperature jumped to 50 degrees and ice went bad. He feels fortunate to have a full-time job, so he can pay for the equipment worth over $100,000, but knows other guides who are struggling.

Seiferlein’s favorite winter catch is walleye — a native species with sweet, mild flesh, whose populations in lakes Huron and Erie have been growing over the past few decades. You can fish for walleye in the summer, but “ice fishing is more fun,” he said. “You’re using a 26-inch pole and you’re jigging up and down. And when one bites, the pole bends over and you fight them and you have to get them through an eight-inch hole. It’s awesome. It’s exhilarating.” 

It’s also big business. Anglers flock to the Great Lakes region from all over the world, with the Michigan Department of Natural resources selling over a million fishing licenses every year. Gone are the days when you would sit on a bucket, out on the open ice, with a $20 pole in hand. Lightweight pop-up shanties that double as gear totes, state-of-the-art insulated winter suits, portable electronic fish finders, underwater cameras and other gear costing hundreds and thousands of dollars made the sport both more comfortable and more popular. According to the 2016 Report by the U.S Fish and Wildlife Service, almost 2 million anglers in the US brave the winter cold, collectively spending over 18 million days ice fishing each winter. 

And while the sport grows in popularity, the number of ice fishing days is growing scarcer. In a paper published in Nature Journal in 2019, Sapna Sharma, associate professor at York University in Toronto, estimated that 14,800 lakes in the Northern Hemisphere experience intermittent ice cover. If the goals of the Paris Agreement are reached, with the international community taking urgent measures to limit the average rise in global temperature to 3.6 degrees above pre-industrial level by the end of the century, that number still would rise, but only to 35,300 lakes. Under scenarios where climate change is addressed less aggressively or not at all, from 90,200 to 215,600 lakes worldwide may start experiencing winters without ice. 

Some areas of the Great Lakes, according to an analysis of data from NOAA, have been losing as much as a day and a half of ice per year on average from 1973 till 2019.

To understand both short-term weather patterns and long-term climate change trends, scientists build models. These models use sets of mathematical equations that follow fundamental laws of physics, chemistry and fluid dynamics to represent natural phenomena, describing how energy and matter interact in different parts of the air, water and land. To do that, the surface of the earth is divided into thousands of cells, with each cell assigned a set of equations. Powerful supercomputers solve the equations, repeatedly passing the results from cell to cell to simulate the passage of time. 

To run their models researchers use standardized climate change scenarios developed by the Intergovernmental Panel on Climate Change, representing a specific amount of pressure human activity puts on the climate. Think of these scenarios as stories of humanity’s future in numbers, projections of what can happen that are plausible, internally consistent and rational. Scenarios most commonly used now are called Representative Concentration Pathways or RCPs — pathways to a specific level of climate forcing. 

As the average temperatures across the globe rise, regional climatic patterns shift, often in unexpected ways. To better reflect such changes, American environmentalist Hunter Lovins coined the term "global weirding," highlighting the increase in the frequency of extreme events — heat waves and cold snaps, violent storms and droughts. With local governments gearing up to confront climate change, forecasting regional effects of climate change in order to better predict its effects on local communities becomes increasingly important.

Anyone who has had to dig out their house from lake effect snow or felt the gales of November can attest that the Great Lakes play an outsized role in local weather. Still, up until now downscaled climate models for this region were unable to fully account for the long-term effect these gargantuan bodies of fresh water have on their surroundings — a problem climate scientists pointed out. 

That is a goal Pengfei Xue, associate professor of Civil, Environmental, and Geospatial Engineering at Michigan Technological University, has focused on in his research, developing a method to fully integrate the physical processes of the Great Lakes into his regional climate model.

As Xue explained, the size and depth of these lakes makes them behave like coastal ocean areas, with jet currents, rolling waves and other phenomena not present in smaller inland lakes. The lakes exert force on the climate around them, while atmospheric changes are transforming the lakes. Current regional climate change models, he said, while being able to provide useful results, up till now have not been able to fully integrate these complex processes. 

Xue’s team developed a regional modeling system that couples the atmospheric climate model to the complex 3-D hydrodynamic model of the Great Lakes. As he described it, the two models can now work side by side, constantly exchanging information between them. This two-way feedback mechanism potentially improves its forecasting capabilities compared with older models, more accurately representing real-world phenomena.

In their latest study they ran their model for two scenarios. RCP8.5, often called "business as usual" or "worst case scenario," assumes no meaningful climate policy. RCP4.5 assumes a fairly aggressive effort to combat climate change. 

Neither of these scenarios is expected to accomplish the aims of the Paris Agreement.

Xue’s study projected that by the mid-21st century ice duration will decrease by 5 to 25 days per year depending on the scenario and location and by the late century up to 60 days in the coastal regions where higher ice covers are typical in the present-day climate. 

“The Great Lakes are massive inland seas,” said David Bunnell, a biologist at the USGS Great Lakes Science Center in Ann Arbor, Michigan. “We are able to monitor relatively small parts of them, relatively few aspects of the food web and relatively few times of the year.”

It takes a lot of time and effort to collect enough data to first detect the patterns, and even longer to understand what is driving those patterns, he said. 

Warming waters combine with other factors, both natural and man-made, to influence fish growth and survival, and every species is affected differently. For example, walleye, a cool water fish, has experienced a recovery in the warming waters of Lake Huron and Western Lake Erie. On the other hand, alewife, an important food source for the Pacific salmon, had a population collapse despite the assumption that warmer springs should aid in its growth. That collapse prompted the return of lake trout, a native cold water species.

Because of the complexity of interactions in ecosystems large enough to be called inner seas, scientists find predictions hard to make. Yet as they chip away at one mystery after another, our understanding of these ecosystems improves. One such study, published in the journal of Freshwater Biology in 2021, looks at climate change and agricultural conservation practices in the Western Lake Erie basin to predict recruitment numbers for yellow perch, white perch and walleye. 

Just like the whitefish, yellow perch and walleye benefit from colder winters. Western Lake Erie’s ecosystem depends greatly on nutrients brought in by the Maumee River, which collects farm runoff from densely developed agricultural lands in Ohio, Michigan and Indiana. The study combined various scenarios for both climate change and agricultural conservation practices to predict that by the 2060s, in most cases, there will be fewer good winters for yellow perch and walleye recruitment while the misleadingly named white perch, a non-native fish belonging to the bass family, would see its numbers rise. Notably, stronger efforts to limit farm runoff may have a negative effect on yellow perch populations. 

Xue’s current model projects that the average annual air temperature on the Great Lakes may increase by 4 to 6 degrees by the end of the century, while the average annual surface water temperature will go up by 1.4 to 4.6 degrees, depending on the scenario and lakes. There will be more precipitation, with the southern and western parts of the Great Lakes basin experiencing the largest increases.

Climate change projections inform the work of biologists and limnologists (scientists who study lakes), but understanding the mechanics of these changes may prove to be even more useful. Xue is currently working with Bunnell, the biologist from Ann Arbor, on a new study about how the currents in Lake Michigan affect alewife, which hatch really small and spend their early lives drifting in the waters. Every species has an optimal spot, Bunnell explained, where the temperature is just right and where its metabolic reactions are perfect for growth. But even if the thermal conditions are optimal, does the species' new habitat provide it with enough food and oxygen? Climate change is transforming the physical and biological makeup of the lakes, altering the lower food web, and we need to understand how those changes percolate throughout the ecosystem.

Momentum to understand the climate drivers of environmental change has been building, Bunnell said. More studies are getting funded and agencies are installing more buoys, collecting temperature data in more spots at more depths and for longer periods of time. New technologies help track fish movement through the lakes, with some even recognizing when a fish is eaten by a predator. And there is an increased effort to understand what happens to the lakes in the winter, a season when historically few studies were done.

We need continued monitoring to identify trends, said Mike McKay, executive director of the Great Lakes Institute for Environmental Research at University of Windsor just across the Canada border from Detroit. 

This February dozens of scientists from both sides of the border, including McKay, went out by foot and on snowmobiles, rode ATVs and hitched rides aboard icebreakers for what they called the Winter Grab. One group even used a fan-powered air boat to go out onto western Lake Erie. They took measurements and collected water samples, working to fill the gap in data collection that satellite readings and autonomous buoy operations cannot provide.

“Winter is still the black box in our understanding of ecosystem function in the Great Lakes,” McKay said. “Unfortunately, monitoring programs are often the first on the chopping block during economic downturns, since they don’t bring immediate returns.” 

While most agencies have acknowledged the threat of climate change, scientists said a lot of funded research so far has focused on other, more immediate stressors like the invasive species. 

“People can easily cut themselves on a zebra mussel when they walk on the shore,” said Randy Claramunt, Lake Huron Basin coordinator at Michigan DNR Fisheries Division. 

But recent events are starting to make climate change impossible to ignore. 

“We have been thinking of these challenges being 20 years down the line, 30 years down the line, but we are getting these today," said Ashish Sharma, atmospheric scientist at University of Illinois Urbana-Champaign.

The 2012 Midwestern heat wave led to 123 deaths and more than $30 billion in economic damage. The 2011 Lake Erie harmful algal bloom was the largest in recorded history. In August 2014 heavy rains caused nearly $1 billion in damage across metro Detroit, and the 2021 summer was the seventh wettest and ninth warmest on record in Detroit.

Stronger storms and lack of ice cover can lead to coastal erosion. There will likely be more lake effect snow. Increased precipitation can cause more agricultural runoff, if not properly managed, producing bigger and stronger algal blooms. Warmer waters can help invasive mussels spread faster and grow bigger; they can also make the waters more hospitable to new, yet unknown, invasive species. 

Climate change will also bring more variability. Water levels in the lakes went from a record low in 2012 to a record high in 2019, a change that was both bigger and quicker than any on record, according to Claramunt. When the water level dropped, he said nearly 3000 spawning reefs turned to dry land. And when it rose again, the opposite happened. 

2022 marks the 50th Anniversary of the Clean Water Act — the first comprehensive federal legislation protecting water quality. Since then, thanks to more stringent regulations and large-scale investments, there have been a number of environmental improvements in the region and across the United States. 

Despite the improvements there is still a spate of problems. Toxic algal blooms in Lake Erie are back, with farm runoff problems worsening. Recent disastrous dam failures highlight the need to address the aging infrastructure. Salt-water-going ships are still coming into the lakes, exposing us to the danger of new, yet unknown, invasive species. And climate change still often gets ignored. 

In recent years biologists at the natural resource departments of the Native American tribes in northern Michigan have been leading the way in trying to use aquaculture to replenish the dwindling whitefish populations. Jason Smith, who works for the Sault Ste. Marie Tribe of Chippewa Indians, has been incubating fish under controlled conditions and then letting them grow in ponds before releasing them into the lake, while his friends at the Little Traverse Bay Odawa Indians DNR have been doing more conventional aquaculture, releasing juveniles in late spring. 

These experiments are only a few years old, and time will tell whether such practices will boost whitefish numbers. Managers need to understand, Claramunt said, all the factors affecting fish recruitment and how they could be handled. Stocking may serve as a stopgap measure but we still need to address the underlying issues. 

To help fish succeed as the changing climate alters their ecosystems, we should reduce the stresses that we already know we are putting on them, Smith said. He refuses to believe the dreissenid mussel problem cannot be solved, but also wonders what new, yet unknown invaders we may introduce. 

Smith supports the proposals to ban ocean ships in the Great Lakes. “Living up here in Indian Country,” he said, “I don’t know anyone who has benefited from these handful of boats, other than maybe having some cheaper TVs at Walmart.” 

The Great Lakes have proven to be resilient, rebounding from many crises throughout recent history, transforming throughout the process, and we have yet to see what climate change will do to them in this century. 

“We often see paradigm shifts and new normals,” McKay said. “They seem to be able to sort themselves out. But is there a point where the stressors on the lakes will be too much and they can’t? I don’t know.”

In recent years many environmental scientists have taken on more prominent roles as advocates, with professional organizations like the American Fisheries Society embracing a more proactive stand in their policies. 

“If Rachel Carson had not advocated when she wrote Silent Spring, we wouldn’t see any robins in the springtime,” he said. “Everyone who cares about the Great Lakes needs to advocate for the Great Lakes. Maybe that really is the best answer I have.”

Alec Gitelman and Allen Cheng are Columbia University graduate students in journalism and statistics. They reported this article with support from Anjanette Delgado, an executive editor at the Detroit Free Press, and Kristi Tanner, a computational journalist at the Free Press.