HOUGHTON – The Michigan Technological University vessel Agassiz assisted staff from Traverse City’s Great Lakes Water Studies Institute at Northwestern Michigan College on Tuesday to recover the body of the last of three boaters who drown while fishing Sept. 17.

Steven Chartre, 43, of Ishpeming, had disappeared along with his 9-year-old son, Ethan, and 61-year-old Keith Karvonen, who owned the 14-foot boat the three set off in that day.

The bodies of Karvonen and Ethan Chartre were recovered Saturday, after being discovered four miles offshore of the trio’s launch site at the Portage Entry, in 280 feet of Keweenaw Bay water, near where the boat rests in an area known as Big Reef.

“Investigators are unable to determine exactly what caused the boat to sink,” a Michigan State Police-Calumet Post press release stated.

Steven had been entangled, requiring a more powerful remote operating vehicle to recover him.

Houghton County Sheriff’s Office, MSP Calumet Post and Mercy Ambulance assisted Northwestern College and Michigan Tech in the recovery.