Michigan’s mild October means more mosquitoes, a threat to cold-water fish

The agency announced three new cases of last week Eastern equine encephalitis in Michigan horses. So far this year, Michigan has recorded eight cases of the deadly virus in animals and none in humans. That’s down from last year’s 41 animal cases and 4 human cases.

But this year’s late-season cases indicate a trend: Warmer falls are allowing zoonotic diseases to spread later in the year and expand their range farther north.

Dinh said Michiganders would remain in danger until the state gets its first hard overnight stop — something pretty much nowhere in Michigan is included in the short-term forecast.

In the long term, Dinh said, the growing threat of insect-borne diseases means Michigan needs a “more comprehensive approach” to combating the problem, such as:

“I hope that these types of programs get more exposure statewide because the mosquitoes are statewide,” she said.

While the salmon and steelhead fisheries in Eade are suffering, some fish species have benefited from mild October, which has lengthened their growing season and allowed them to put on more weight ahead of winter, said Gary Whelan, program manager with the Michigan Department of Natural Resource Fisheries Division.

But cold-water fish like salmon and steelhead are stressed, he said.

“Their reproductive cycle tells them it’s time to spawn based on sunlight,” Whelan said. “But the temperatures aren’t.”

This results in some fish spawning later, which also means their eggs are likely to hatch later in the spring, potentially posing survival challenges for next year’s young.

The warmer weather has also resulted in a slower start to the autumn migration season. Once the weather cools, waterfowl migrate down from Canada. Holy Vaughn, spokesman for the DNR wildlife department, said the fall duck hunting season has been slower than usual so far.

Welcome to the new normal

Bigger changes are ahead, said Rood, the UM researcher. As climate change continues unabated, summers in Michigan continue to lengthen while autumns and springs contract.

Since 1951, average air temperatures in the Great Lakes region have risen 2.3 degrees Fahrenheit, and Michigan has lost 16 days of annual frost. Surface water temperatures in the Great Lakes have been rising even faster than the air, with Lake Superior warming 4.5 degrees Fahrenheit since 1979.

To make matters worse, a landmark global rating The study, published this summer, warned that humanity faces at least three more decades of worsening climate impacts from continued burning of fossil fuels, even as the world’s governments and economies quickly abandon fossil fuels to become carbon neutral by 2050.

With these changes now in place, Stow said, “the past may no longer be a good predictor of the future.”

In other words, this warm October is not all that unusual. It is a predictable consequence of a changing climate.

And while today’s version of climate change in Michigan is manageable compared to the massive wildfires and droughts of the west, or the mega-hurricanes and rising seas along ocean shores, “it could be a very different story 30 years from now,” Rood said.

DNR’s Whelan said this is bad news for the long-term survival of Michigan’s cold-water fish in some rivers and lakes.

“This will be a big challenge for future biologists,” he said.

Aside from the noticeable immediate effects, such as plentiful mosquitoes and delayed fish migrations, warm Octobers can produce long-term changes that are harder to see right now.

For example, Rood said, cold snaps that occur suddenly after warm weather can stress or kill trees, creating new opportunities for invasive plants to gain a foothold. Over time, Rood said, these subtle changes would result in “massive disruption.”

He said Michigan shouldn’t just take note of the changes by having bug spray on hand later in the year or installing sump pumps to deal with worsening summer flooding. Instead, he said, we should anticipate and adapt to the changes we will see in the coming decades.

That means preparing our public health system for worsening insect-borne diseases, training first responders to respond to more heat-related emergencies, and training contractors to design new buildings that can withstand climate threats.

Eade’s fishing group has taken this advice to heart, with an increasing focus on advocating removing dams that are artificially slowing and heating Michigan’s rivers.

As Michigan summers get longer, he said, “we’re going to need this colder water to keep these trout healthy and alive.”

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