And South Australian coroner David Whittle says "prudent" offshore fishermen should consider equipping their lifejackets with GPS-enabled personal locator beacons.
On Thursday, he delivered findings into the eight deaths in 2024 and 2025, after an inquest that examined whether there was a systemic issue in the use of lifejackets in the state's marine safety regime.
In the first incident, Paul Eckert, 73, Thomas Eckert, 40, and Alan Bottrill, 71, all drowned after their boat was overturned by a wave at Buffalo Reef, 55km east of Port Lincoln, on March 25, 2024.
Thomas Eckert's brother Danny and his 13-year-old nephew managed to swim to the reef and were winched to safety the following day.
The coroner focused on the "comprehensive and well-organised" rescue operation after witnesses established that a wave almost three metres higher than the boat had overturned the vessel.
On August 14, 2024, the bodies of Kangaroo Island professional fishermen David Neave and Rodney Ingram were found near their overturned boat, off Cape Cassini, hours after the alarm was raised when a thick fog set in.
Mr Whittle found that capsize was "a plausible and likely scenario" that occurred after fog had obstructed landmarks and the vessel may have inadvertently navigated close to a reef "resulting in a wave taking them by surprise".
In the third incident, fisherman Peter Martin, 77, drowned off Cape Finniss, near Elliston on the Eyre Peninsula on November 30, 2024.
Mr Whittle found that Mr Martin's boat capsized as he attempted to retrieve a cray pot which was snagged on the sea floor, most likely as a result of an accident while winching the pot rope.
The fourth incident occurred on January 6, 2025 in Rivoli Bay near Beachport, in the state's South-East.
Victor Kent, 69, and Roger Walker, 82, died after their boat capsized while they were checking cray pots.
None of the people who died in the four incidents were wearing lifejackets.
"While it is not certain whether these deaths would have been prevented, the use of lifejackets would have given each person at the very least a strong chance of survival," Mr Whittle found.
In most states, including SA, lifejackets must be worn on boats less than 4.8m in length, and at all times by children aged 12 or younger.
A threshold of seven metres would mean 93 per cent of registered boats had a mandatory lifejacket obligation, Mr Whittle said.
He recommended that SA "lead the nation" and make lifejackets mandatory for anyone aboard a powered vessel up to seven metres in length.
For ultimate safety, rescue services and prudent fishermen travelling significant distances from shore should equip their lifejacket with personal locator beacons capable of GPS broadcasting, he said.
