The fight to save scores of beached whales in one of New Zealand's biggest whale strandings on record was far from over as more of the animals washed up on the coast.
A new pod of 240 whales became beached on Saturday just hours after volunteers managed to refloat a different group following an earlier mass stranding.
Saturday's group brought to more than 650 the total number of pilot whales that have swum ashore along the 23km Farewell Spit since Thursday.
About 335 whales have died on South Island's sands, 220 remain stranded and 100 were sent back to sea by volunteer rescuers.
"We want to try and determine if there's an underlying reason why such a large number of whales stranded and died in such a short space of time," veterinary pathologist Dr Stuart Hunter told the New Zealand Herald.
"It's not unusual for pilot whales to strand en masse, but this stranding is unusual due to the sheer number of whales involved and in such a small amount of time."
Andrew Lamason, manager of the Department of Conservation Golden Bay, said on Saturday they are sure they are dealing with a new pod because they had tagged all the refloated whales from the first group and none of the new group had tags.
The news was devastating for hundreds of volunteers who had come from around the country to help with the initial group of 416 stranded whales that were found early on Friday, many of them already dead.
Volunteers are planning to return Sunday to help refloat as many healthy whales as they can to the waters.
Lamason said conservation workers euthanised about 20 of the new group because they were in poor condition. More would probably need to be killed on Sunday, he said.
Improved weather and crystal clear water had helped with the rescue attempt.
Lamason said about 100 surviving whales from the initial group were refloated.
Dozens of volunteers had formed a human chain in the water to prevent them from beaching again.
| Volunteers came from across the country to help the stranded whales [Reuters]
Volunteers were warned about the possibility of stingrays and sharks after one of the dead whales appeared to have bite marks consistent with a shark.
Farewell Spit, a sliver of sand that arches like a hook into the Tasman Sea, has been the site of previous mass strandings.
Sometimes described as a whale trap, the long coastline and gently sloping beaches seem to make it difficult for whales to navigate away from once they get close.
There are different theories as to why whales strand themselves, from chasing prey too far inshore to trying to protect a sick member of the group or escaping a predator.
New Zealand has one of the highest rates of whale strandings in the world, and Friday's event was the nation's third-biggest in recorded history.
The largest was in 1918, when about 1,000 pilot whales came ashore on the Chatham Islands. In 1985, about 450 whales stranded in Auckland.
Source: News agencies