The Indonesian man was on the deck of the Olivia Jean vessel when the incident happened at around 10pm on June 28, 2019.
He was struck on the head by a scallop dredge towing bar while the vessel was approximately 39 miles north-east of Aberdeen.
The fisherman suffered crush injuries to his head and was airlifted to hospital for emergency treatment but died 12 days later.
An investigation by the Marine Accident Investigation Branch (MAIB) said: “The crewman had replaced two worn dredges on the towing bar and stood clear as the skipper used the winches and derrick to lift and realign the gear against the vessel’s tipping door.
“Unfortunately, one of the towing bar’s securing chains had not been released and the dredge gear became snagged.
“Although the skipper shouted instructions to the crewman to remain clear as he attempted to free the gear, the crewman stepped between the snagged bar and the accommodation superstructure just as the snagged bar released and swung inboard.”
The accident happened out of the skipper’s line of sight, according to the MAIB report, and he was relying on a CCTV screen behind him to monitor the area – suggesting the deck operations “were not being properly supervised or controlled”.
It also found the “deck crew’s level of English comprehension was poor, and they did not speak a common language”.