Great Lakes’ Cold-Water Fish Habitats under Climate Siege

As climate change reshapes the cold-water habitats, the question looms: Can people harmonize with the Great Lakes to ensure a future where both sides survive?

By Orkhan Huseynli

The Great Lakes—Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario—span an impressive 95,000 square miles, playing a key role in the lives of over 35 million people in the United States and Canada. These ancient reservoirs, holding 84 percent of North America’s surface freshwater, are not just bodies of water, but witnesses to history and guardians of diverse ecosystems.

However, there is a realization that the narrative of the Great Lakes Basin is not static. It is a living, evolving piece, shaped by geological forces, human choices, and the relentless challenge of global warming. Currently, a contrasting story of resilience and climate pressures takes center stage. It sets off a global domino effect, potentially affecting tourism, agriculture, biodiversity, and all the elements that make life around the Basin thrive.

How Does Climate Change Affect the Great Lakes?

Trout - Great Lakes' Cold-Water Fish Habitats under Climate Siege
Trout (Photo: Freepik)

Elevated air and water temperatures contribute to increased evaporation from the Lakes, resulting in lower lake levels and compromised water quality. The swift reduction in ice cover during the coldest seasons serves as a warning that fish and aquatic wildlife are under severe strain. Lake Superior, for instance, has experienced rising temperatures and an earlier start to summer stratification, advancing by approximately two weeks in the last 30 years.

Plankton, crucial for aquatic balance, is losing their protective ice shield. As the Lakes stratify, lower levels risk oxygen depletion, creating ominous “dead zones.” Coldwater fish species, such as whitefish and lake trout, now contend with challenges from warm-water rivals moving north. In the next three decades, a typical winter might render Lake Superior mostly ice-free, impacting whitefish reproduction.

No longer mere witnesses, the Lakes now implored humanity to catalyze resilience, shaping a harmonious future for their ecosystems. It’s a commitment not just to weather the storm but to actively redefine the narrative of the Great Lakes’ ecological future, demanding a unified response to confront the challenges at hand.

Fish Head Boat on a choppy lake
Fish Head Boat Charter: Grand Haven, Michigan (Photo: T. Lawrence, GLFC)

Studies Taking Account Climate Projections

Brock University’s Environmental Sustainability Research Centre in Canada, under the guidance of Associate Professor Julia Baird, emerges as a beacon of collaborative determination. Their recent study extends beyond unraveling the complexities of climate change adaptation.

It signifies a commitment to understanding and addressing factors contributing to the resilience of these vast ecosystems []. The center’s efforts, a convergence of diverse stakeholders, vividly depict resilience and strategic response. “It’s clear that there’s no time to waste in addressing climate risks and impacts in Niagara and across the Great Lakes,” warns Baird.

As early as 2003, the Report of the Union of Concerned Scientists and the Ecological Society of America painted a grim picture of extreme heat, shoreline erosion, and wetland degradation in the basin [].

The Issues along Minnesota’s North Shore Rivers

Acknowledging that not every chapter can be salvaged is crucial as we navigate this story of change. Minnesota’s North Shore rivers, renowned for cool trout streams, face a dire forecast.

By mid-century, over a third of these streams are predicted to become too warm for the beloved sport fish. Dean Paron, a state scientist and paramedic, recognizes the need to make incredibly tough decisions with limited resources. “I’ve had times where you have five patients, and you have to make very tough choices,” shared Paron. “That’s very akin to this experience.”

While Minnesota adopts a “Resist, Accept, Direct” strategy for vulnerable North Shore rivers, Michigan is on the verge of recognizing causes that may be deemed lost []. 

The Department of Natural Resources (DNR) is subtly deciding to stop prioritizing cold-loving fish in places deemed unsustainable. Tough choices loom, and the DNR may face increasingly difficult decisions about which rivers are worth the effort.

Projections for the Effect on Fish Populations

Scientists project alterations in the distribution of fish species under a 2xCO2 climate scenario across 209 locations in the contiguous United States [].

Projections indicate that cold-water fish habitat may endure in deep lakes along the northern border but faces potential eradication from the majority of shallow lakes within the contiguous states, potentially resulting in a 45 percent and 30 percent reduction in suitable cold-water and cool-water fish habitat across lakes, respectively.

Wide blue lake under a cloudy sky
Lake Erie, Ohio (Photo: loganwengerphotos/Pixabay)

The status of trout and salmon, acting as ecological barometers, is of paramount importance. Flourishing in temperatures below 70 degrees, any deviation beyond this threshold poses a threat to their survival.

Recent research findings published in the journal Ecosphere suggest a concerning trajectory—by mid-century, over half of Michigan’s 300 high-quality cold-water lakes may no longer meet the classification criteria [].

Conversely, the prognosis for warm-water fish habitats appears optimistic, with an anticipated expansion. The average duration of optimal growth periods is projected to increase by 37 days for cool-water fish and an even more substantial 40 days for warm-water fish.

Delving into fish population dynamics, historical data has been harnessed to predict growth pattern shifts for both warm-water species, exemplified by smallmouth bass and yellow perch, and cold-water species, such as lake trout, in response to evolving climatic conditions. Elevated air temperatures and premature warming of surface waters have been identified as triggers for accelerated growth in smallmouth bass and yellow perch.

In stark contrast, lake trout exhibits diminished growth rates, ostensibly attributable to the early onset of water stratification, curtailing the feeding window for trout fry in surface waters due to rapid warming.

Potentially Beneficial Areas for Investment

The Environmental Protection Agency is pinpointing key areas for federal investments aimed at safeguarding and restoring the Great Lakes.

Over the past 13 years, Congress has allocated nearly $4 billion for over 7,000 projects under the Great Lakes Restoration Initiative. Various strategies, from stream cooling to habitat restoration, emerge as tools within GLRI in the collective arsenal against the encroaching impacts of climate change.

Strategies emerge, from cooling streams with shade trees to removing dams and harmonizing to counteract threats from warming waters [].

Efforts to rehabilitate degraded habitats have fortified projects focused on reintroducing native lake trout and Atlantic salmon in Lake Ontario. Additionally, the recovery of the native deep-water sculpin once believed to be extinct, has been observed. Meanwhile, endeavors to reintroduce other native prey fish through stocking initiatives are displaying promising indications of success [].

Largemouth Bass
Largemouth Bass (Photo: T. Lawrence, GLFC)

Initiatives Working for Positive Change

Earlier this month, the Sustain Our Great Lakes partnership announced $17.6 million in grants for 43 projects—the largest slate in its history. The partnership, backed by the GLRI, focuses on restoring habitats and enhancing water quality.

Administered by the National Fish and Wildlife Foundation, the grants support initiatives across the Great Lakes basin, including stream restoration, fish passage, wetland preservation, and regenerative agriculture. Since 2006, the program has awarded over $128 million in grants, leveraging an additional $155 million for a total conservation investment exceeding $283 million.

Chris Korleski, director of the Great Lakes National Program Office, emphasized the power of collaboration, stating, “We are able to leverage Great Lakes Restoration Initiative funds to increase the investment in on-the-ground projects to reduce stormwater runoff, restore habitat, and reduce sedimentation and nutrient runoff. Working with federal and non-governmental partners, corporate and nonprofit partners and grant recipients we are able to support projects that make a difference in communities and improve water quality across the Great Lakes basin.” []

Another initiative—The Great Lakes Fishery Trust actively invests in programs to enhance access, conduct fisheries research, and promote stewardship for the Great Lakes. Through strategic funding, the trust works to ensure sustainable and resilient fish communities while fostering public engagement and awareness of the lakes’ ecological importance.

The Trust is actively engaged in conservation genomics to manage and regulate the lake sturgeon fishery in the Great Lakes [].

Hopes for the Future

Recognizing the profound significance of the Great Lakes to Canada’s environmental and economic well-being, the government’s commitment to safeguard these invaluable water resources is commendable. Minister Patty Hajdu’s announcement of $663,500 in funding for six Thunder Bay projects signifies a proactive stance toward restoring water quality and ecosystem health.

These initiatives, spanning from habitat restoration to fishway optimization, not only tackle immediate concerns but also align with Canada’s broader objective of cleaning up critical areas and meeting phosphorus reduction targets [].

Despite these challenges, Karen Alofs, an assistant professor at the University of Michigan specializing in the effects of warming temperatures on Great Lakes fish, underscores the significant role people can play in preserving biodiversity: “Humans can have a lot of impact on preserving that biodiversity.”]

About the Author

Orkhan Huseynli

Orkhan Huseynli is a freelance science and environmental writer. His academic journey has encompassed fields such as Public Administration, Management, and Economics, culminating in a master’s degree in Environmental Economics and a Ph.D. specialization in Industrial Management.

Transitioning from a career in IT, Orkhan is now dedicated to pursuing his passion for science and popular science writing. Orkhan is keen to contribute his writing skills to the world of articles and essays, covering topics like Climate Change, Biodiversity, Environmental Economics, Ecology, Paleoscience, and Environmental Politics.

For him, the prospect of writing for scientific outlets represents a chance to share his knowledge and raise awareness about crucial scientific advancements, fulfilling his aspiration to engage with a broader readership.

Get in touch with Orkhan on Facebook.
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