Chathams find is biggest octopus ever

By ANNE BESTON environment reporter

The biggest octopus ever found has been caught by New Zealand scientist Dr Steve O'Shea off the Chatham Islands.

The giant dead octopus, which was caught by the National Institute of Water and Atmospheric Research's ship Tangaroa, is not complete, but still measured 2.6m.

Intact, it could have been a metre longer, said Dr O'Shea, a marine biologist and researcher with Niwa.

The octopus was caught as a byproduct of Tangaroa's fish stock survey late last year but was not examined closely at first because Dr O'Shea thought the brilliant red gelatinous blob was just another giant squid - the animal he specialises in.

After catching more than 70 giant squid over the past 10 years, he thought this one could wait a while before he took a closer look.

When he did, he found the giant animal was the first confirmed record in the South Pacific of the rare gelatinous octopus Haliphron atlanticus - and the largest specimen known.

Dr O'Shea said the haliphron was poorly understood though it had been recorded that the female brooded eggs in her arms.

It was once thought to be part of New Zealand fauna but has since been struck off the list because of a lack of scientific evidence.

Most of those caught had been juveniles found in depths of less than 33m, although a few larger animals had been found at depths exceeding 250m. The octopus is thought to live on or very near the sea floor.

Scientists also thought the biggest the octopus grew was 2m. Dr O'Shea said it was remarkable, given the number of juveniles caught, that large adults had not been caught more often.

This one was found on the Chatham Rise at a depth of less than 1000m, an area and depth that had been extensively trawled for decades.

"Either it has escaped trawl nets for decades or it usually resides in areas or depths that we have yet to regularly sample," he said.

Because the biology of the species has not been reported in detail, especially one as large and mature as this female, it would now be fully scientifically described.

The discovery brought the total number of octopus species known to exist in New Zealand waters to 42, Dr O'Shea said.

He had notified the find around the world.

nzherald.co.nz/environment