A Hawaiian fisherman died when a swordfish he had speared in a harbour on the Big Island struck him in the chest with its sharp bill, officials said.

The man, a captain in the charter fishing business, on Friday morning saw the swordfish in the Honokohau small boat harbour and jumped into the water to catch it, the state Department of Land and Natural Resources.

Witnesses say he speared the fish but it struck him in the chest with its spear-shaped bill, according to the department.

Onlookers pulled the unresponsive man out of the water and performed CPR until paramedics took him to a hospital where he was pronounced dead, the department said in a statement.

The man was not named in the statement but local television station KITV identified him as 47-year-old Randy Llanes.

"He was a tough guy, he was such a tough guy that everyone's scared of him, the whole harbor's scared of him," Kalina Llanes, the man's sister-in-law, told the station.

She added that those who knew him well were "not scared of him because he has such a big heart."

KITV showed an image of the fish, which according to the Department of Land and Natural Resources measured 3 feet long with a bill that extended another 3 feet, lying dead at the water's edge.