The Hawaii Fire Department and Coast Guard crews are searching for a 63-year-old Captain Cook man who went overboard while fishing on a boat off Honaunau on Sunday morning.

Hawaii Island police also launched a missing person investigation for Mark Knittle, described as 5-feet-10 inches, 185 pounds, with curly brown hair and white mustache and beard.

It was reported to police that on Sunday at 5 a.m., Knittle and a friend were fishing near the “C” buoy, four miles outside of the Honaunau Boat Ramp, when Knittle hooked an ahi. The friend heard Knittle say, “the fish is huge,” then he saw Knittle go overboard.

The friend attempted to grab the line but was unsuccessful, police said, and the man disappeared into the water within seconds.

Fire Department and Coast Guard personnel plan to conduct a 72-hour search, officials said.

Anyone with information about this incident is being asked to call the police department’s non-emergency line at (808) 935-3311, or email Officer Melani Cline at melani.cline@hawaiicounty.gov.