On the most northern island of the Orkney archipelago in Scotland, a mass stranding of 89 pilot whales is thought to be the biggest the country has seen in 100 years.

A deteriorating situation

Locals began reporting the stranded whales on the beaches of Sanday in the morning of Thursday the 11^th, however, when rescuers arrived later that day 77 of the animals were deceased after being on land for several hours, 12 individuals were still alive. The British Divers Marine Life Rescue (BDMLR) regional team met with a small number of medics on the island to assess the situation and it was decided later that day that it was best for the remaining 12 pilot whales to be euthanised.

The update provided on the BDMLR website stated “Sadly the remaining 12 pilot whales have been euthanased due to their condition deteriorating from the many hours they have spent stranded on the beach resulting in crush injury from their own weight and the high likelihood that they have inhaled water with the incoming tide. The substrate they’re on is also incredibly soft meaning they have sunk even deeper into the sand when the tide washed over them, so they unfortunately weren’t able to refloat themselves”.

 Credit: BBC

Over the weekend, specialists in cetacean strandings and members from the Scottish Marine Animal Stranding Scheme (SMASS) travelled to Orkney to investigate the event. Multiple whales were necropsied for post-mortem or sampled for further pathology investigation as to why the event occurred and to reveal more about the lives of the individual whales. The pod included a vareity of ages and was made up of both male and female individuals.

Stranded individuals appear to have been healthy

Mariel ten Doeschate, from the Scottish Marine Animal Stranding Scheme, told BBC Scotland News that thorough post-mortems had so far been carried out on about 30 whales. She said: “Just about everyone in the UK who is involved with whale strandings is here on Sanday.

 “We’ve been taking samples to determine the health status of the whales before the stranding and according to our initial preliminary findings, they all seem to have been healthy.

 “So it’s unlikely there was a sick leader who they were trying to stay with and protect.” 

Social creatures

Pilot whales are social animals that live in matriarchal pods, with the oldest female holding authority. Ms. ten Doeschate explained to the BBC that the whales stranded close together as a behavioral stress response, likely triggered by a sound or predator that frightened them into clustering.

Ian Wiese, chair of Geographe Marine Research in Western Australia, spoke to the Daily Mail online said pilot whales are often the species involved in these sorts of events. “They are deep water whales and if they are close to shore it seems to indicate that something is wrong – probably with their navigation as they shouldn’t be so close to shore, here are a lot of theories as to why this occurs but we don’t really know.“

“They are very social and form large pods, so when an incident of this nature occurs there are normally a lot of whales involved.”

Investigators have collected ear samples from six key whales to check for acoustic trauma. The research associate emphasized that the investigation aims to ensure the whales “did not die in vain,” as the findings could aid in future conservation efforts for wild whales. The team is also investigating the presence of killer whales in the area at the time of the stranding.

Read more about whale stranding investigations here.