Reporter's Notebook: Sharks in Lake Superior?

Greg Isaacson knows that Lake Superior is shark free. And he's thankful for it. He ran into a tiger shark while scuba diving in the Hawaiian Islands. That was enough for him. But one day he paddled out into the lake and saw a giant shadow pass underneath his board. Then it jumped from the depths below, causing Isaacson to nearly piss his wetsuit.

To understand what the hell jumped from the water, we called up John Lindgren, a fisheries specialist at the DNR office in Duluth.

Good news: Lake Superior is shark free.

Bad news: there are fish in it that can scare the hell out of you.

"They're called Porpoising Sturgeon," says Lindgren. "And they usually leap in July and August."

According to Lindgren, such fish were placed into the bay and lake in the late '70s. And it took a steady improvement in water quality to get where they are today. (That is, jumping out of the water like dolphins.) Some of the sturgeon are now 25-years-old and around 50 to 55 inches, about the size of a female gymnast. And they're an ancient fish and pretty much all cartilage. Just like a shark.

Crap.

But at least they don't really bite.

"They suck," says Lindgren and adds. "And maybe they'll suck your toe off."

Guess it's better than lake monsters with a periscope eye, tentacles and fangs...