The trawler was fishing off south-eastern Australia when it killed four dolphins in one haul, according to the Australian Fisheries Management Authority (AFMA).

It has also killed two more seals, repeating the tally of six marine mammals deaths that occurred on the trawler's first trip last month, as it fishes offshore for jack mackerel and redbait.

After the first series of deaths, AFMA set a limit of three dolphin deaths before the vessel had to cease night fishing.

The vessel's spokesman, Graham Turke, said the 95 metre had fitted a new acoustic deterrent device to the trawl net.

"During a trawl run the mechanical failure of a net haul winch left the net, with a haul of fish, suspended in the water for a period of 30 minutes," said Mr Turk, of the Small Pelagic Fishery Industry Association.

"While the deterrent device may have been effective on other trawl runs, the facts are four dolphins pushed past this device and become entangled in the trawl net," he said.

The Geelong Star has ceased fishing and will return to port for further investigation and gear improvement, Mr Turk said.

AFMA said in a statement that it would participate in the review to determine how to minimise further marine mammal interactions.

The Australian Marine Conservation Society's campaigner Tooni Mahto said the killing of dolphins by fishing boats was unacceptable to the Australian public.

"It's absolutely clear the vessel cannot fish without killing dolphins, so therefore the vessel should not fish," Ms Mahto said