The Coast Guard's Cleveland office says the man began calling in 2010, making claims such as that his boat is sinking. The Coast Guard is posting 15 recordings to see if anyone recognizes the man's voice.
Lt. Justin Westmiller in Detroit says the calls could cause a disaster by diverting rescuers from a real emergency.
He says the prank caller uses marine band radio VHF-FM Channel 16. It's the international hailing and distress frequency.
Westmiller says the calls come from the Bolles Harbor area on Lake Erie in Monroe County's Monroe Township.
The U.S. Coast Guard asks that people with tips about the fake mayday caller to call 800-773-2587.
Fake mayday calls: http://bit.ly/WIkrQX