Grand Traverse Bay isn't freezing as much as it used to, causing ecological concerns, officials say
Ice cover on Lake Michigan is happening less and less, and that’s why Grand Traverse Bay hasn’t frozen this year.
“We’ve got calm waters in the western arm of Grand Traverse Bay. No ice formation yet,” says Heather Smith, baykeeper at The Watershed Center Grand Traverse Bay.
The bay had already frozen out to Power Island by this time last year and the year before.
“We typically see the bay freezing in February or March. There are a few years when it did freeze in late January, but that is typically when we get those long periods of cold weather,” Smith says.
Historically, dating back to the mid-1800s, Grand Traverse Bay would freeze more than 50 percent of the time, she says. In the last two decades, it froze less than 30 percent of the time.
Winter temperatures across the midwest are the eighth warmest on record, according to the Midwestern Regional Climate Center.
Additionally, Lake Michigan is about one degree warmer this winter than it was last, according to the National Oceanic Atmospheric Administration.
“In the last 20 years, the bay has only froze six times so we’re seeing a reduction in ice cover in the last 20 years in the Grand Traverse region, and that’s really in parallel with what we’re seeing in all of the Great Lakes,” Smith says.
The changing climate is to blame, she says.
According to the NOAA, ice cover has been on a "downward trend since the 1970s" across the Great Lakes.
That has big impacts for fish, says Steve Pothoven, a fisheries biologist for the NOAA.
“For something like a whitefish, it’s typically thought to be good if you have ice cover during the winter,” Pothoven says.
Whitefish spawn in November and hatch in late March or early April, so ice cover is good to protect the eggs from turbulent waters and wave action, he says.
“That’s just kind of been the holy grail for whitefish,” Pothoven says.
However, ice cover is not great for other species like Alewife and yellow perch, and winter can be hard for those fish, he says.
Although Alewife is an invasive species, introduced salmon — a popular sportfish — rely on Alewife for food.
“Everything is just sort of a matter of perspective of what you’re looking at, there’s tradeoff,” Pothoven says.
According to Smith, ice cover also affects water levels and shoreline erosion.
“More evaporation can lead to lower lake levels. I know that everyone is watching that very closely, as we’re in one of our very high lake level years,” Smith says.
If the bay doesn’t freeze, that means more wave action will hit the shoreline, increasing erosion over the winter, she says.
How about other bays up north?
The Straits of Mackinac are frozen enough for ice hockey. St. Ignace hosted the annual Labatt Blue Pond Hockey Championship last weekend.
Ice also has locked in the Star Line Ferry that takes passengers to and from Mackinac Island — for now.
It stopped running on Valentine's Day, says Samantha York, marketing coordinator for Star Line Ferry.
“So right now it is pretty frozen over. Not anywhere near enough for the ice bridge to form yet, however it has frozen enough to lock us into the dock and keep us from our departures,” York says.
The “ice bridge” is what locals call the route on the ice from the island to St. Ignace. It’s when the Straits of Mackinac completely freeze, allowing locals on the island to take snowmobiles to the main land on the ice bridge.
York is used to the ferry being iced in until spring, but she says some people think the upcoming warm temperatures will break things up in the Straits.