A whale rescued by experts after becoming stranded on the Lincolnshire coast has died.
Rescuers said the whale would have been stressed by being out of water
Rescue teams had towed the 18ft (5.5m) long northern bottlenose male whale three quarters of a mile (1.2km) out to sea and he was able to swim to safety.
But East Lindsey District Council said the mammal had been found washed up on a beach near Skegness.
Rescuers said the whale probably suffered dehydration and stress from being out of the water for many hours.
His female partner, who was also beached, died earlier after attempts were made to save her.
A team of scientists from the Zoological Society of London were carrying out post mortem examinations at the scene on Friday.
A spokesperson from the society said this was standard protocol and tests on the female whale should be completed by Friday afternoon.
She said: "Working closely with our colleagues at the Natural History Museum, data and samples will be collected as part of the UK Marine Mammal Stranding Project."
Rescuers were called to the beach where the two whales had become stranded on Thursday afternoon.
Floating pontoons were used to refloat them at high tide but efforts failed and the female whale died in the evening.
Teams then worked through the night to save her male partner.
Rescuers feared he had died when he stopped breathing for 18 minutes but he was revived and towed out to sea.
His carcass was found on beach in the Seacroft area on Friday morning.
A spokesman from the British Divers Marine Life Rescue said the whale was in relatively shallow water in the North Sea, compared with its natural habitat of the Atlantic and could not feed on deep ocean squid, which could have caused it to become dehydrated.
He said it would also have suffered stress after being on its side and out of water for many hours during the rescue.
A 30ft (9.14m) sperm whale was found washed up on beach at Skegness in February.