A large sperm whale was overseen by the organization's volunteer Marine Mammal Medics as it floated on Friday, October 11, in Newbiggin-by-the-Sea, Northumberland off the coast.
A statement on the BDMLR Facebook page confirmed on Friday night that the creature had died.
The whale was 13.3 meters long and could have weighed up to 30 tons.
The public was in Newbiggin-by-the-Sea, watching the beast after being discovered in shallow waters.
The organization's statement states, "Unfortunately, but as expected, the whale stranded in Northumberland later that afternoon and died shortly thereafter.
"Some of our volunteers were escorted from shore to carcass tonight to confirm the death and take measurements and photos for the national database maintained by our colleagues at the Cetacean Strandings Investigation Program – UK Strandings of the Institute of Zoology. London.
"It is hoped that arrangements can be made for the team to conduct a post mortem inspection to further uncover what may have happened to this animal."
Sperm whales are a specialized deep-sea diving species that should not normally invade the North Sea, as the depth is far too shallow and their usual prey to squid is very low.
They should normally be found many miles west of Britain outside the continental shelf, which is their usual habitat.
The animal in Northumberland is well over 400 km from its home.
The British Divers Marine Life Rescue has advised the public to avoid contact with the Walkadaver while the necessary work continues.
The statement added, "It is very important to note that whales are mammals like us humans and therefore can transmit serious illnesses that can be transmitted between us.
"We advise the public to avoid any contact with the carcass and any bodily fluids to avoid the risk of infection, and there is a possibility that this was an animal that was already ill."