Minke Whale Necropsy in the Eden Estuary

Balaenoptera acutorostrata? That sounds like hakuna matata!”

After an incredible time sailing around the sunny Hebrides on the Silurian, the MSc Marine Mammal Science class was back in St Andrews and ready to get stuck into our research theses for the final 3 months of the Masters course.

I’d just gotten off the bus, after traveling back from the Isle of Mull that afternoon, and was slowly walking home when my phone dinged and I saw a message saying “Minke Whale stranded on West Sands”.

After checking with classmates that it wasn’t a belated April Fools joke, a group of us jumped in the car and made our way to beach. At the very end of West Sands beach, we found a small huddle of people around the stranded whale. We were all sad to see that the Minke whaMinkeWhaleEntanlementMarks_SMASSle was already dead.

The corpse looked relatively fresh, with limited signs of decay or bloating. Initial observations made by the group pointed out signs of possible entanglement – most notably of which was a deep abrasion on the whales’ caudal peduncle (where the tail meets the body) as well as bruising and abrasions on its tail.

The tide was coming in so we all headed back home and waited with anticipation for the Scottish Marine Animal Stranding Scheme team to arrive from Inverness the following day to do a necropsy (i.e. an animal autopsy).

The tides moved the Minke Whale into the Eden Estuary overnight. Thus, upon arriving on Thursday morning, we waded out to the Minke whale and Kelly Macleod (Senior Marine Species Advisor at JIMG_0834_ClairEversNCC) tied a rope around its tail. We gently pulled the whale closer to shore in order to secure it in shallow water.

I had expected the whale to be heavy and difficult to maneuver, however the decomposing corpse had started to inflate with gas and thus it floated with surprising ease across the water surface. It was strange to think that it was easier to maneuver the whale than it was to simply stay warm in the nippy North Sea.

The team from the Scottish Marine Animal Stranding Scheme (SMASS) arrived in the afternoon and set to work on taking the necessary measurements, skin and blubber samples from the Minke Whale.MinkeWhale_SMASS

Staff and students from the Sea Mammal Research Unit (SMRU) donned blue plastic gloves – ready to help in any way we could – and watched in fascination as the SMASS team investigated the carcass.

Some notable memories of the day –

  • People’s reaction to the rotting gas being released from the whale. Whilst this is not a very jovial thought or memory, it definitely had an immediate effect on the onlookers as the whooshing noise and pungent smell had people quickly shimmying upwind.
  • Seeing the lungs immersed in a substantial amount of seawater within the whale. These observations were consistent with the animal becoming caught in a rope and, being unable to surface and breathe, quickly drowning.
  • Noting that the muscle was not as dark as that of the Pilot Whales (which we had seen during the necropsy in October). We realized that this is due to the fact Minke whales do not generally dive as deep as pilot whales and thus do not need to store as much myoglobin (and thus oxygen) in their body.
  • Cutting into the whale’s eye and exploring the lens held within – which was slightly cloudy (an indication of cataracts).
  • Exploring internal sections of the whale – including the ‘pluck’ (composed of the trachea, heart and lungs), pelvic bones, inner ear bone and goose beak (a modified larynx).

The SMASS team concluded that the sub-adult Minke whale died of recent, acute entanglement and otherwise appeared to be healthy – however they highlighted that it is important to confirm this with additional testing (from the samples they had taken).

For example – looking at the contents within the whale’s stomach can reveal what the Minke whale had recently been eating and eMinkeWhale_0867_ClairEversxamination of the inner ear bone can indicate the extent of underwater noise that the whale had been exposed to.

Additionally, a necropsy can provide insight into the whale’s general health by assessing its body condition, signs of disease and the presence and abundance of parasites.

It was a very surreal and sad event, especially after we all had had such incredible encounters with Minke whales just a few days previously on the West Coast.

Alas, entanglement is the most common cause of death diagnosed in Minke whales, causing around 32% of mortalities for the species and most frequently in creel lines. Whale entanglement is a worldwide problem and it is therefore imperative to examine such cases when possible to better understand how we might be able to help prevent such occurrences in the future.

More news on the great work done by the Scottish MariMinkeWhale_0840_ClairEversne Animal Strandings Scheme (SMASS) can be found on their facebook page.

Information on how to report a stranding in the UK can be found at the UK Cetacean Strandings Investigation website.

Written by Riona Bray

P.S. And yes, the whale (and we) made the news:

the Daily Mail

the Courier