A Bull Shark Was Caught in Illinois. Here's How It Got There.

In 1937, two commercial fishermen near Alton, Illinois, pulled a five-foot bull shark out of the Mississippi River — more than a thousand river miles from the Gulf of Mexico. Some called it a hoax. Scientists say it was real. Bull sharks are native to American coastal waters, but they can do something almost no other large shark can: survive in completely fresh water. Their kidneys switch modes, and they can travel far up rivers — from Lake Nicaragua to thousands of miles up the Amazon. A second "Mississippi shark" from 1995 turned out to be a probable hoax. But in 2013, two eight-foot bull sharks were caught in nets where the Potomac River meets the Chesapeake Bay. And in North Carolina's Pamlico Sound, researchers found something new: young bull sharks starting life farther north than before. This is the story of the bull shark — the shark that doesn't stay in the sea. They Were Never Supposed to Be Here. Subscribe to Invasive America for new wildlife investigations. Tell us in the comments: is there a river, bay or lake near you with a shark story? 📚 SOURCES & FURTHER READING Sharks in Illinois — the 1937 Alton bull shark (In-Fisherman) Shell, Gardner & Hrabik — Correction on upper Mississippi bull shark records (Marine and Fishery Sciences) Bangley et al. — Increased abundance and nursery habitat use of the bull shark in Pamlico Sound (PMC) Two bull sharks caught at the mouth of the Potomac River (WBAL) Unprovoked shark bites in 2024 (Florida Museum, International Shark Attack File) A Shark in Fresh Water? (UT Marine Science Institute) In 1937, a five-foot bull shark was pulled from the Mississippi River in Illinois. How did it get a thousand miles inland? Bull sharks are unique among their kind for their ability to navigate freshwater environments. While we typically associate them with coastal saltwater, these predators possess specialized kidneys that allow them to travel thousands of miles up major river systems, from the Amazon to the Mississippi. As a freshwater shark, they can survive in conditions that would kill almost any other large shark species. We examine the historical record of the Illinois shark, investigate recent sightings in the Potomac River, and look at new research on nursery habitats in North Carolina. While not always classified as an invasive species, their presence so far from the ocean creates a unique wildlife mystery. This is the story of the bull shark—the shark that doesn't stay in the sea. They Were Never Supposed to Be Here. Subscribe to Invasive America for new wildlife investigations. Tell us in the comments: is there a river, bay, or lake near you with a shark story? #BullShark #Sharks #MississippiRiver #SharkFacts #Illinois #PotomacRiver #ChesapeakeBay #PamlicoSound #FreshwaterShark #RiverShark #SharkInIllinois #GreatLakes #WildlifeDocumentary #NatureDocumentary #InvasiveAmerica