Mitchell Guist, who starred on the History channel reality show “Swamp People” with brother Glenn, was pronounced dead at a Louisiana hospital Monday. He had fallen while aboard his boat on the Intracoastal Waterway, near Pierre Part. He was 47.

A seizure or heart attack was suspected, though it is uncertain whether the attack caused the fall or visa versa; an autopsy will have to be undertaken to determine the cause of death.

“Swamp People” follows residents of Louisiana’s Atchafalaya swamp country during alligator hunting season.

History and Original Media, producer of the show for the cable network issued a statement: “We are extremely saddened to report that our friend and beloved member of the ‘Swamp People’ family, Mitchell Guist, has passed away earlier today. Mitchell passed on the swamp, doing what he loved. We appreciate your respect for the Guist family’s privacy and hope you join us in sending our thoughts and prayers to his brother, Glenn, and the rest of the Guist family.”

(Associated Press contributed to this report.)