Each summer, researchers throughout the Great Lakes watershed head out on the water to collect water quality and ecosystem health data. The information gathered is critical for monitoring changes to Great Lakes ecosystems. But there is a glaring gap in this data collection: winter data.
Why is winter understudied?
Winter is an understudied season in the Great Lakes, largely due to the challenges of collecting data in colder temperatures. While many researchers get out on the water from late spring to early fall, collecting data in the winter has more challenges—the water is cold and icy, which makes it much more dangerous and requires highly trained personnel and specialized equipment. This is also true in the shoulder seasons of late fall and early spring, when the water is too cold to safely be out on a boat, but not cold enough for solid, safe ice to form. Without sufficient data from the winter and shoulder seasons, a large piece of the puzzle is missing in understanding the ecology of the Great Lakes.
Why do we need winter data?
Historically, there has been a long-running misconception that winter is a time of stagnation—that not much happens in lakes in the winter. This assumption is far from the truth! There are a whole host of important processes going on in those icy waters. Some species of fish, like burbot, even spawn under the ice! Collecting more winter data would allow us to better understand just how much life and activity is present in these cold winter waters.
What happens in the winter also has a huge impact on summer water conditions. Winter influences everything from water temperatures to fish communities to algal blooms. For instance, a winter with more algae growth due to low ice cover and warmer temperatures could mean a summer with larger blooms, which can have implications for drinking water and recreation.
More data on winter conditions would help to create a complete picture of the ecology of the Great Lakes, which in part would allow decision-makers and lake managers to make more informed decisions. This is especially important now, as winter conditions shift alongside a changing climate.
| Winter data gaps | Significance |
|---|---|
| Ice | More ice data would improve understanding of changing freeze up dates, decreasing maximum ice-cover, and earlier ice break-up dates. |
| Coastal processes | Loss of ice along shorelines impacts erosion and the morphology of Great Lakes shorelines. |
| Light | Changing thickness and quality of ice impacts light penetration, which can result in temperature changes and changes to winter ecological processes. |
| Nutrients | More frequent winter melts and rain are expected to increase nutrient run-off into the Great Lakes. |
| Salt | More data is needed on chloride loading (chloride entering lakes) from road salts used in the winter. |
| Fish | Assess winter fish ecology, including how winter impacts spawning, food availability, and invasive species. |
| Food webs | Understand how changing winters impact food webs in the Great Lakes. |
| Human well-being | More data is needed on the socioeconomic and cultural implications of changes to winter, including winter drownings, ice road transportation, and recreational and cultural activities. |
Changing winters
Over the past few decades, lakes have seen an increase in water temperature and a decrease in ice cover. Ice cover has decreased around 0.5 percent annually in the Great Lakes since 1973. Since 1995, winter conditions have also gotten shorter by about two weeks each decade. It is clear that winter is changing in the Great Lakes, and we need to understand more about these changes in order to better adapt. These changes impact not only the ecology of the Great Lakes, but also many people’s way of life.
Less ice cover means fewer opportunities for winter recreation, including skating, snowmobiling, and ice fishing. It also means that winter transportation may become less reliable, as vehicles can no longer travel safely over ice. Many Indigenous communities rely on ice for travel and for traditional practices such as hunting, fishing, and gathering. Winter changes can impact the seasonal timing of important cultural activities and the availability of culturally significant species. More winter research would help increase our understanding of these socioeconomic impacts.
What is being done to address this need?
In recent years, there have been increasing efforts to collect winter data, including the “Great Lakes Winter Grab” project. An innovative project launched in 2022, the Winter Grab is a cross-border collaboration between universities in Canada (including Trent, Lakehead, and Windsor) and researchers from the United States. This initiative aims to improve the coordination and sharing of data, resources, and knowledge, all while filling in gaps in water data collection.
Travelling on foot or by snowmobile, Winter Grab teams use specialized equipment to drill through the ice and collect data about water quality and life under the ice. Participants of the Winter Grab have sampled all five Great Lakes, Lake St. Clair, and the St. Lawrence River.
This season, the Cleveland Water Alliance is facilitating testing of technologies such as underwater telemetry and monitoring devices to understand how they perform against ice and extreme cold. Ice can damage equipment and block sensors, disrupting data transmission. Extreme temperatures can challenge electronic components and battery life of devices. Understanding how these technologies perform in winter conditions is imperative to improving designs for future monitoring.
Despite these efforts to fill gaps, more work still needs to be done. A May 2025 report from the International Joint Commission Great Lakes Science Advisory Board strongly recommends an increase in efforts to improve capacity and coordination in collecting Great Lakes data in the winter. This would involve providing more training opportunities, such as the Winter Limnology Network training workshop held in 2024, making investments in new technologies, such as autonomous underwater vehicles, and incorporating wintertime monitoring into current monitoring protocols, such as the Cooperative Science and Monitoring Initiative (CSMI) sampling cycle.
With increased efforts to collect data in the winter, scientists and researchers can begin filling in the missing pieces and gain a more complete understanding of life in the Great Lakes—for now, and for the future.
