Sharks In Lake Michigan? Climate Change Makes It More Likely (2024)

Community Corner

Bull shark sightings have been confirmed in Missouri and Illinois, and scientists say they could swim farther inland with climate change.

Posted Thu, Jul 28, 2022 at 2:11 pm ET|Updated Fri, Jul 29, 2022 at 1:59 pm ET

It doesn’t happen often, but some shark species can thrive in freshwater, and climate change could increase the chances of an encounter with a shark in the landlocked Midwest, Kevin Feldheim, who conducts shark research at Chicago’s Field Museum of Natural History, told AccuWeather.

At least two sharks have been sighted in the Mississippi River over the past century, Feldheim told AccuWeather national weather reporter Emmy Victor. The first was in Alton, Illinois, in 1937, and the second was in Missouri in 1995.

Bull sharks have a nasty reputation, deserved or not, in part because of their size, growing to about 11 feet long and weighing around 700 pounds. They are apex predators that don’t mature until they’re around 15 or 20 years old.

They are also marvels of nature.

Bull sharks’ kidneys recycle salt water, so they’re able to swim through rivers and lakes, according to National Geographic. Others among the hundreds of shark species scientists have identified can live only for a while in the brackish, somewhat salty water in estuaries — the area where freshwater rivers and streams meet the ocean, also called a bay, lagoon, sound or slough.

With the warming climate, and the potential summers as much as 11 degrees Fahrenheit warmer, bull sharks could swim far from their coastal ranges to the north central U.S., Feldheim, who heads the Field Museum’s Pritzker Laboratory, told AccuWeather.

How Worried Should Midwesterners Be?

Still, the likelihood of a shark encounter in freshwater is low, experts said.

For one thing, lock-and-dam systems on the Mississippi could stop sharks from swimming farther inland, Ryan Shell, a paleontologist for the U.S. Forest Service, told The Alton (Illinois) Telegraph.

For another, there aren't as many bull sharks as there once were to make the swim up the Mississippi.

Bull sharks are at risk of extinction, according to Oceana, a conservation and research organization endowed by The Pew Charitable Trusts, Oak Foundation, Marisla Foundation, Sandler Foundation and the Rockefeller Brothers Fund.

They’ve been overfished, like other plummeting shark populations worldwide, but their biggest threat is accidental capture in fisheries targeting other species, according to Oceana.

“Most of these accidental captures take place when these sharks are upriver,” Oceana said on its website, adding that while bull sharks are occasionally targeted in culling operations to increase beach safety, those practices have done little to protect people from sharks.

Bites Up And The Coast

The odds of a shark attack are practically zero, despite the recent spate of shark bites on both coasts.

• Read More: What’s The Likelihood Of A Shark Attack?

So far this year, there have been 28 shark attack bites in U.S. coastal waters, none of them fatal, in Florida (16), New York (6), California (2) and South Carolina (2), according to a database on the Tracking Sharks website.

That compares to 47 shark attack bites in 2021, 36 shark attack bites in 2020 and 50 shark attack bites in 2019. Florida led all states in each of those years.

Earlier this month, an angler fishing in the Florida Keys who was bitten by a 6-foot-long lemon shark as he tried to remove a hook from its mouth was airlifted to a Miami hospital.

• Read More: Shark Bites The Hand That Tried To Free It

Shark bites this month have been reported much farther north. In early July, a lifeguard was bitten by a shark on his chest and hand in what Steve Bellone, the top executive in Suffolk County, New York, called an “unprecedented” event.

“This is the first time that we are aware of that we have had anyone bitten by a shark,” he said at a news conference.

That would rapidly change.

A couple of weeks later, a shark bit a surfer, knocking the 16-year-old off his board and gnawed a 4-inch gash in his leg. The surfer “took a punch at the shark,” which circled back after the initial bite and came at the teen, Bellone said.

“At that moment, fortunately, a wave carried the surfer and the paddle board back to shore,” he said.

A few hours after the surfer was bitten, a 49-year-old Arizona man was standing in waist-high waters off a Long Island beach when a shark came from behind and bit him on the buttocks and wrist. He was able to walk out of the water on his own and had minor injuries.

• Read More: Shark Bites Swimmer’s Behind

Shark attacks are rare — and fatal attacks are even less common in the United States — but the rapid succession of bites off Long Island are “an indication that what we are looking at is something of a new normal” as sharks swim closer to shore, Bellone said.

• Read More: Sharks Close To Shore ‘New Normal’?

Shark bites have been reported off the Pacific coast as well. A surfer in Pacific Grove, California, was hospitalized in June with severe stomach and leg injuries after a possible shark attack. The beach was temporarily closed.

How Did Freshwater Sharks Avoid Detection?

Stories like those give pause to landlocked Midwesterners. And while Shell, the forestry service paleontologist, and others say that while there’s no need for panic, inland sharks could become more common.

Shell told AccuWeather that while it may be easy to dismiss the two confirmed reports of bull sharks in the Mississippi River “as one-off events, that ignores the interesting questions of how these animals evaded detection and got so far upstream in the first place.”

It could happen more with climate change.

Worldwide, bull sharks thrive in fresh water, according to Oceana, which said their freshwater routes of bull sharks have included the Nicaragua River in Central America and the Zambezi River in Africa. Under the right conditions, they more or less live there.

In fact, “there is a semi-permanent population in Lake Nicaragua that was thought until recently to be a separate species,” Oceana said, noting bull sharks can give birth in freshwater.”

“During these long periods inland, bull sharks come into close contact with people, and most of the incidents when they have bitten people have been in rivers rather than the ocean.”

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