Shark attack could be behind New Zealand whale strandings

Hundreds of whales that were stranded on a New Zealand beach could have come onshore because of a shark attack, rescue officials said.

More than 400 pilot whales were stranded on South Island on Friday. Most of them died and rescuers were trying to help surviving ones back into the sea on Saturday.

One whale had been found with bite wounds and great white sharks were known to be in the area, said Department of Conservation ranger Mike Ogle.

"There's one carcass out there with some shark bites in it - but not a big one, just a small one, but quite fresh bites so yeah, there's something out there."

Rescuers defied a shark threat to form a human chain in a bid to keep a further 200 whales from becoming stranded.

About 150 people in the human wall were also attempting to prevent some 100 survivors from Friday's beaching from returning to the shore.

The sun was making it difficult for volunteers to keep the whales cool while they waited for the late morning high tide to get the mammals back into the water.

The area, about 150 kilometres (95 miles) west of the tourist town of Nelson, is notorious for whale strandings and has witnessed at least nine mass beachings in the past decade.

When the first mass beaching of 416 pilot whales was found on the beach on Friday morning nearly 300 were already dead.

Pilot whales grow up to six metres (20 feet) long, and are the most common species of whale in New Zealand waters.