SCOTTYTORIAL

THE GREAT FREEZE-UP AND WHY IT MATTERS

It’s January. My morning scroll of the Lake Huron MODIS satellite imagery happens over coffee. Produced daily by NOAA CoastWatch (Great Lakes Region), the MODIS satellite is one of the tools used to measure surface ice concentration on the Great Lakes.

Nine out of 10 of these images usually turn out completely cloud-covered and provide zero insights into current lake ice conditions. But every so often a clean image reveals itself following a clear day and details a visual update of the lake surface as it freezes over the course of winter.

In 2015, a rare freeze-up occurred: Lake Huron peaked at over 95 per cent ice concentration, the volume of surface ice necessary for a winter crossing of the Bay. Zane Davies and I made the 88-km SUP trek that winter, departing from Neyaashiinigmiing and arriving at Twelve Mile Bay after three days of navigating through the labyrinthine aqua firma. After that, the door was shut and the winter of opportunity hasn’t formed since.

Historical ice-cover graphs appear like a heart rate monitor that oscillates and contracts along a linear chart. The second-highest peak for ice concentration ever recorded happened in 2014 at 92.4 per cent coverage across Lake Huron (followed a few years later by a low 19.4 percent ice coverage in 2017). It bounced back up to 80.9 percent in 2019 whereas 2020 generated another low at 19.5 percent.

The frequency of years hitting extreme low is increasing year to year, while the span between them is notably shrinking. These extremes affect more than 6,100 km of shoreline across Lake Huron, and force drastic environmental changes upon coastal animals, birds and fish.

For native fish species of the bay such as lake whitefish (Coregonus clupeaformis; atikamekw in Anishinaabemowin), surface ice is a shield of defence from the brutality of winter storms. Whitefish spawn along shallow rock reefs in the fall, and their eggs must endure the long winters in order to hatch in spring. Less ice means less protection for their life cycle.

The shallow waters between outer reefs and the shore become protected nurseries for native fish species, and shoreline ice acts as a buffer or breakwall that protects the surface from being stirred into significant wave action. Ice cover also filters out the sunlight from penetrating deep into the water.

Light penetration and prolonged wind events can also disrupt the spawning cycle of cisco (Coregonus artedi; odoonibiins in Anishinaabemowin)—a vital native preyfish species who prefer to spawn in the dark motionless waters beneath snow-covered ice.

Similar to whitefish and other native fish, cisco populations have been heavily depleted by fisheries over decades.

Ice cover on the bay has helped protect and nurture these native species that were once plentiful and evolved with the formation of ice and the seasonal cycles of the Great Lakes region.

I hope for more winters like 2015, when we made our successful SUP crossing of the bay. For the sake of those fish beneath the ice and their young. And for the families they feed. And for future generations, that they can experience the wintry wonders of the bay as I’ve been lucky enough to know them. What would it mean if the old winters never return? That’s something I cannot fathom. –Scott Parent

Navigating over ice and open water during the 2015 SUP crossing of Georgian Bay. SCOTT PARENT