An investigation into the cause of the fire aboard Talley's fishing boat Amaltal Columbia is expected to take a year, but investigators have finished inspecting the scene of the fire and talking with crew.

The Transport Accident Investigations Commission (TAIC) began its inquiries into the cause of a major fire on the fishing vessel two days ago when the ship was dragged into port at Lyttelton Harbour hours after the 43 crew abandoned ship.

The Nelson-based 64 metre factory trawler had put out a mayday call at 5.30am Wednesday morning after a fire had started in its meal hold about 85km off the Lyttelton Heads.

Some of the crew were taken to hospital for ammonia and carbon monoxide poisoning, but all made it off the ship safely. The four crew suffered poisoning while trying to unload fish from out of a part of the hull which was unaffected.  

TAIC said today, two investigators had completed their scene investigation of the fire and had finished gathering evidence. They had now released the Almaltal Columbia back to its owners.

While the investigators had also completed interviews with the crew involved, further interviews would be carried out over the next few weeks.

"The Commission's inquiry will set out to explain the cause of the fire and identify any lessons that might prevent the chance of a similar event happening in the future, as well as review the way in which the situation was handled on board and during the rescue and recovery operations.

"The inquiry is expected to take at least a year to complete.  The Commission has the ability to issue safety recommendations at any time, should an inquiry turn up something that should be addressed urgently by others," said TAIC spokesman Peter Northcote.

The Commission was investigating to establish the cause of the fire, and identify any lessons to be learned in preventing a similar incident happening again.

It would also review how the situation was handled on board and the rescue and recovery operations.

Northcote said it would take at least a year to complete.

- © Fairfax NZ News