Locals sighted the pod on the isle of Sanday in Orkney on Thursday morning.
The British Divers Marine Life Rescue (BDMLR) was called in to assist the whales at about 10.45am on Thursday (7.45pm Thursday AEST).
By the time medics arrived, the whales had evidently been stranded for several hours already and only 12 of the 77 animals were still alive.
The medics began health assessments and gave first aid to the surviving animals as the incoming tide approached, in the hopes they could be refloated.
Medics also believe there was a “high likelihood” the whales inhaled water with the incoming tide, further injuring them were unable to be refloated.
Medics also believe there was a “high likelihood” the whales inhaled water with the incoming tide, further injuring them.
The medics were forced to euthanise the remaining animals.
“There are no obvious indications as to why they all stranded,” BDMLR reported.
“It may be some time before full results are available due to the huge task of conducting these examinations.”