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Are There Sharks in The Great Lakes? Lakes Ontario | Michigan | Superior

Are there sharks in the Great Lakes? This question keeps popping up and it got us curious…

So once for all we are going to find out if it is really possible for a shark to get to the Great Lakes and even to survive in freshwater.

If you haven’t yet heard of the Great Lakes, here are some amazing facts about them:

Great Lakes consists of 5 lakes bordering the U.S. and Canada and they are among the largest freshwater bodies of water in the world. In fact, they resemble vast inland seas.

Let’s take a closer look at these 5 beautiful lakes and learn some facts about sharks and their habitat.

Sharks in Saltwater vs. Freshwater

To begin, I learned that sharks by nature are designed to live in a saltwater. Without the salt to process into their bodies, they simply cannot survive.

One noteworthy exception is the bull shark. This shark specie has the capability to recycle salts through its kidneys and survive in freshwater surroundings.

Therefore, bull sharks are the only potential shark that could live in the Great Lakes.

Are There Sharks in The Great Lakes

Water Temperature

Most sharks do not like to live in cold waters and tend to avoid big changes in water temperature.

Bull sharks are the only specie that could survive in freshwater and if they did end up in a lake, it would be in summer when the water is warmer.


It is definitely not an impossible task for sharks to swim from the Ocean to the a lake.

Sharks have been found thousands of miles up the Amazon River, and as far up the Mississippi River as Illinois, about a 1,700-mile journey from the Gulf of Mexico.

The good news is that the cold water at the mouth of the St. Lawrence River makes it unlikely that sharks could travel the eastern route from the Atlantic Ocean towards the Great Lakes.

Recommended reading:

A Great Lakes Roundup

The Great Lakes are diverse in their geographic location and natural characteristics, and that makes it challenging for even the possibility of a bull shark to get there.

Are There Sharks in Lake Superior?

Green Bay Lake Superior

Lake Superior is the largest and most northern of the Great Lakes. It is massive, ranking as the world’s largest freshwater lake by surface area.

It stretches from Ontario on its northern shores around to the states of Minnesota, Wisconsin and Michigan.

Its average water temperature is a chilly 40 degrees Fahrenheit.  This alone can rule out the survivability of any shark that even managed to reach these waters.

Are There Sharks in Lake Michigan?

Lake Michigan’s shorelines face the cities of Chicago and Milwaukee, and border the states of Wisconsin, Illinois, Indiana and Michigan.

It carries the distinction of being the largest lake in area in any one single country. What were the odds of a shark on the loose in these waters?

Sharks in Lake Michigan

To begin with, an electrical barrier was installed starting in 2002 in the Chicago River where it feeds into the lake.

This was built as a deterrent against invasive species such as the Asian Carp. This invisible barrier would help deter shark entry as well.

In addition, sharks need water temperatures of 70 degrees or more to survive.  Lake Michigan’s waters only surpass that temperature several weeks a year, so the habitat is not generally suitable for sharks.

I found an article quoting Phillip Willink, senior fish biologist at Chicago’s famous and well-respected Shedd Aquarium.

He says that all shark reports for Lake Michigan have turned out to be hoaxes.

I wanted to dig deeper and find out what specific instances of shark sightings or encounters have taken place in or near Lake Michigan.

Are There Sharks in Lake Ontario?

bull shark Lake Ontario

Lake Ontario is bordered by Ontario (including the city of Toronto) and the state of New York.

The last in the Great Lakes chain, Lake Ontario connects to the Atlantic Ocean through the Saint Lawrence River.

The lock system in the St. Lawrence seaway would serve as a manmade barrier to sharks seeking to traverse the river towards the Lakes.

A 2014 purported video of a bull shark in Lake Ontario turned out to be a hoax, with a full-size shark model used.

This was done to attract attention to the Discovery Channel’s Shark Week programming!

Recommended reading:

Are There Sharks in Lake Erie?

are there sharks in Lake Erie

Lake Erie is the is the southernmost, shallowest, and warmest of the Great Lakes.  It borders Ontario and the states of Michigan, Ohio, Pennsylvania and New York.

Cleveland and Buffalo are the largest lakefront cities.

There are no scientifically documented reports of sharks here.

However, in the 2021 book Sharks in Lake Erie by area resident H. John Hildebrandt, an eco-terrorist organization secretly introduces six adult bull sharks into Lake Erie.

Evidently sharks in these waters is still a topic that captures the popular imagination.

Are There Sharks in Lake Huron?

Lake Huron is the most easterly part of Lake Michigan, connected by the Straits of Mackinac.

It borders the Canadian province of Ontario and Michigan.

Although there have been reports of dead sharks washed up on Lake Huron’s beaches, there is no proof as to whether they arrived on their own or were simply left as a prank.

A Real-Life Fish Tale

are there sharks in the Great Lakes?

Early proof that a shark could make its way about 1,700 miles up into Illinois came in 1937 when two local fishermen caught a 5-foot, 85-pound bull shark in the Illinois River.

Since then, there have been dams installed that would prohibit other sharks from making the same journey! Still, it showed that a bull shark could survive traveling long distances in fresh water.

Shark Attack Fact or Fiction?

Then there is the fascinating case of a 1955 shark attack in the Lake of one George Lawson, reportedly bitten on the right leg.

This was documented in the so-called Global Shark Attack File, compiled by the nonprofit Shark Research Institute.

Trouble is, when researchers have tried to verify the story, neither the victim nor his rescuer was found!

So, what was the source for the story?

An enterprising local researcher found that a 1975 picture book entitled Man Eating Sharks referenced the 1955 attack.

The publisher was a British entrepreneur named Felix Dennis, since deceased.

But one of his writers recalled long hours researching that story but couldn’t recall whether all the story was totally accurate.

are there sharks in Lake Erie

1975 was the year that the famous movie Jaws appeared.  The film frightened moviegoers away from swimming in the sea for fear of a Great White shark at large.

There is a sense that the publisher was looking to capitalize on the furor the movie generated to sell books and may have played fast and loose with historical facts.

The fact is that there is no record of the event in Chicago newspapers.

This seemed completely illogical to me not have recorded an event that would have so captured public attention regarding the safety of the swimming public!

But the story lives on, perhaps more as an urban legend now.

Recommended reading:

Dead Sharks and Questionable Photos

More recently, in 2008 a fisherman from Traverse City Michigan found a dead 2-foot-long juvenile black-tip shark in the lake waters.

However, he didn’t know whether the shark made its own way into the lake.  Had it been caught elsewhere and thrown overboard in the lake or was it the basis of some prank?

A 2014 photo of a possible shark sighting stirred up some initial excitement due to the apparent dorsal fin breaking the water.

Later the photographer himself admitted he couldn’t be sure it was a shark.

How Else Could Sharks Get to the Lakes?

Are There Sharks in The Great Lakes

One interesting alternative posed for how a bull shark could reach Great Lakes’ waters is the ship ballast water theory.

Container ships take on ballast water in their holds to help the ship balance itself properly in the water when they have no cargo or insufficient cargo in their holds.

The shark could be pulled in with the ballast water in a saltwater port.  It would then feed on other fish similarly held as the ship journeys to its Great Lakes port.

There it would release the ballast water, along with the hitchhiking shark.


So are there sharks in the Great Lakes? My conclusion is based on the facts, and they don’t lie! Although nothing is impossible 🙂

First, only the bull shark of all shark species has the physical capacity to survive in freshwater.

Even if one made it to the Lakes, only in summer would the water temperatures in some of the Lakes be high enough for it to survive.

Are There Sharks in The Great Lakes

Next, the physical distances for a shark to travel from a saltwater source to the Lakes is daunting though not impossible.

Most routes also pose obstacles such as river lock systems that would make it highly unlikely for a shark to successfully navigate through them.

The ship ballast water theory presumes that there were other species captured for the shark to feed on during the long journey.

It also would depend on the time of year the ship arrived to allow for warm enough water temperatures for the shark to live.

It seems highly unlikely, yet not entirely impossible, that a bull shark could survive for brief periods in some of the Great Lakes in the summer.

I think the U.S. and Canadian residents must take comfort in the belief that they will not likely have to share their favorite swimming and boating destinations with these potential visitors!

Recommended reading:

Planned Shark Encounters

Are There Sharks in The Great Lakes

Although the prospect of running into a bull shark in the Great Lakes is less than appealing, what if you want to experience these beautiful creatures up close, but safely?

There are various places around the world you can either swim or snorkel amongst sharks or see them up close.

Here are some ideas:

1. Plunge into the blue waters of the lagoons of Bora Bora in French Polynesia for a shark snorkeling safari or shark diving and feeding adventure.

2. Experienced divers can enjoy shark diving off Australia’s Rainbow Beach north of Brisbane.

3. Game fishing, including shark fishing, is a specialty of the charter boat fleet operating out of Kiama harbor, New South Wales, Australia, about 1.5 hours south of Sydney.

4. For those who want a little more distance between themself and the sharks, you can combine tropical island beauty with a visit to the Oceanarium in the Islas del Rosario in the Colombian Caribbean south of Cartagena.

Recommended reading:

To learn more about bull sharks, check out this article from National Geographic.

This YouTube video, In Search of Canada’s rogue shark, is an interesting exploration of whether sharks, in particular bull sharks, could make the journey up the St. Lawrence River into Lake Ontario.