Rescuers were forced to abandon efforts to save around 150 melon-headed whales that stranded on a beach in Japan on Friday, after frantically trying all day to save them.
As darkness fell, local officials in Hokota, about 100 kilometres (60 miles) northeast of Tokyo, said they had been able to save only three of the 149 animals that had beached and that the rescue effort had been called off.
The rest of the creatures, a member of the dolphin family usually found in the deep ocean, had either died or were dying, they said.
"It was becoming dark and too dangerous to continue the rescue work at this beach, where we could not bring heavy equipment," said an unnamed Hokota city official.
"Many people volunteered to rescue them but the dolphins became very, very weak."
"Only three of them have been successfully returned to the sea, as far as we can confirm," he added.
Locals and coastguard teams had battled through the day to save the animals, trying to stop their skin from drying out as they lay on the sand.
Others were carried in slings back towards the ocean.
Television footage showed several animals from the large pod had been badly cut, and many had deep gashes to their skin.
An AFP journalist at the scene said that some of the creatures were being pushed back onto the beach by the tide soon after being released, despite efforts to return them to the water.
"We see one or two whales washing ashore a year, but this may be the first time we have found over 100 of them on a beach," a coastguard official told AFP.
The pod was stretched out along a roughly 10-kilometre-long stretch of beach in the Ibaraki area, where they were found by locals early Friday morning.
"They are alive. I feel sorry for them," one man at the scene told public broadcaster NHK, as others ferried buckets of seawater to the stranded animals to pour over them.
Massive efforts were required to get the three that survived back into the water.
Rescuers wrapped them with blankets before putting them on a coastguard vessel. The animals were taken to waters about 10 kilometres from the shore and released, according to NHK.
Footage showed many of the less fortunate animals laying in shallow waters, too weak to swim, being pushed back and forth by the waves.
While the reason for the beaching was unclear, Tadasu Yamadao, a researcher at the National Museum of Nature and Science, said the dolphins might have got lost.
"Sonar waves the dolphins emit might have been absorbed in the shoals, which could cause them to lose their sense of direction," he told the Yomiuri Shimbun.
Melon-headed whales, also known as electra dolphins, are relatively common in Japanese waters and can grow to be two-to-three metres (six-to-nine feet) long.
In 2011, about 50 melon-headed whales beached themselves in a similar area.
Friday's rescue effort stood in marked contrast to the global view of Japan and its relationship with cetaceans.
Despite international opprobrium, Japan hunts minke and pilot whales off its coast, and has for many years also pursued the mammals in the Antarctic Ocean using a scientific exemption to the international moratorium on whaling.
It has never made any secret of the fact that meat from the animals is consumed.
A UN court ruled last year that its hunt was a commercial activity masquerading as research and ordered it be halted.
Tokyo, which insists whaling is a tradition and labels environmental campaigners as "cultural imperialists", has vowed to restart a redesigned southern ocean whaling programme, possibly later this year.
Coincidentally, four whaling vessels set out Friday to hunt up to 51 minke whales in the northwestern Pacific, in a separate hunt that was not covered by the UN court ruling.
Japan also defies international opinion with the annual slaughter of hundreds of dolphins in a bay near the southern whaling town of Taiji.
The killing was brought to worldwide attention with the Oscar-winning documentary "The Cove".