Published: Apr 03, 2013 5:46 PM EDT

LEE COUNTY, Fla.- A judge found Steve Marconi guilty on Wednesday, of killing a protected species of shark, off the coast of Sanibel.

Florida Fish and Wildlife officials stopped Marconi in his boat in December. When officers arrived, they found a large sandbar shark tied to the side of the boat. Marconi says the fish attacked him in 60 feet of water and he had to kill it to save his own life. The judge didn't believe it.