Dead Marine Animal Strandings
Andy Summers and I have undergone training by the Scottish Marine Animal Stranding Scheme (SMASS) to safely take tissue samples from dead stranded marine animals.
“SMASS has been in operation since 1992. It is part of the Cetacean Strandings Investigation Programme (CSIP), and is funded by the Scottish and Westminster governments. The project aims to provide a systematic and coordinated approach to the surveillance of Scotland’s marine species by collating, analysing and reporting data of all whales, dolphins and porpoises (collectively known as cetaceans), seals, marine turtles and basking sharks that strand on the Scottish coastline.”
2022 so far
This year so far has been relatively busy with several Harbour Seals, Phoca vitulina, and Grey Seals, Halichoerus grypus washing up around the coast of Assynt. Most of these were immature animals, and often too far decomposed to take meaningful samples.
There have also been three cetaceans reported so far in 2022. As is very often the case these strandings are first seen and reported by members of the public. Andy, being the Highlife Highland Countryside Ranger tends to be the recipient of most of these reports.
When we are made aware of a stranding the first step is to visit the site and record some basic details and take photographs to forward to SMASS. They will then advise us if they would like tissue samples taken. If samples are requested they provide a case reference number in the format ‘M123/22’. This number is then written on all sample pots which are sent back to SMASS in Glasgow.
The samples taken are: skin, blubber, muscle, and teeth if possible. Blubber and muscle samples measure approximately 5cm x 2cm x 2cm, and the skin is 5cm x 2cm. Generally, 4-6 teeth are taken.
All the samples help build a picture of the health of the individual animal and of the wider population of the particular species. They do not provide a cause of death for which a full necropsy is required.
Back to 2022 and the three cetacean strandings
The first report was on 14th January, and it came from Sean Wain. It was an immature Common Dolphin, Delphinus delphis on the beach at Balchladich. Andy made a quick visit the following day to confirm the ID and take some basic measurements. He then dragged the animal slightly further up the beach to take it away from the high tide which might refloat it.
SMASS issued Andy with a reference number and asked for samples.
We both went back to take the samples on the 17th. No sign of the remains! A storm in the intervening period had either buried the animal under sand/seaweed/rocks or re-floated it and deposited it elsewhere. It has not yet been reported again.
Second report
The next stranding was reported by Stevan and Helen Lockhart on 26th January. This was a very recently stranded juvenile female Harbour Porpoise, Phocoena phocoena. This animal had stranded on Stoer beach. Photo 1.
Stevan has reported strandings to us previously so was aware of also letting SMASS know about this one.
As this animal was so fresh SMASS came and collected the entire carcase the same day. They took it back to Glasgow for a full necropsy.
On 31st January the SMASS Strandings Coordinator Nick Davison MSc reported this-
“At post mortem, there was gross evidence of trauma to the head, it otherwise appeared to be in good condition. What caused the trauma to the head is unknown it could be a boat strike, but we cannot be sure.”
Third report
The final cetacean stranding to date was notified by Neil Cameron on 4th February, and this was a very young Common Dolphin on Clachtoll beach. Photos 2-5.
Again, Andy visited the same day. This time he made sure the animal was moved well up the beach and securely left in the dunes!
SMASS confirmed the animal was suitable for sampling so on 5th February we met at Clachtoll. Given the gale force wind and horizontal sleet we decided to move the carcase to the shelter of the far side of the salmon bothy.
There we were able to measure the animal’s length (120cm) and girth (62cm) just in front of the dorsal fin. We were also able to ascertain that it was a female, and from the still visible ‘foetal folds’ that it had been very young. Photo 5.
These vertical lines on young dolphins are as a result of the foetus having to be ‘folded’ in the uterus. They will disappear over time but are a useful ageing clue. This link to the Seawatch Foundation website gives a fascinating insight to Pregnancy and Birthing in Bottlenose Dolphins. A different species but the same process.
Sampling
There were no visual signs of injury so we proceeded to remove a 2cm wide strip of skin+blubber+muscle from the centre of the back to the centre of the underside. The thickness of the blubber is one other statistic noted for SMASS. It varied from 18mm to 19mm.
The strip of tissue removed was then dissected to separate the three layers, and these were finally divided to provide the necessary samples as mentioned earlier. Last thing was to remove some teeth. On that topic, there are an additional two clues in Photo 3. that tell us this was a young animal.
First clue is the teeth, or lack of them. You can see that the lower jaw still has a good number of teeth that haven’t yet erupted. Secondly the ‘feathering’ towards the tip of the tongue. These are known as marginal papillae, and while they can still be present in later years they are much more pronounced in younger animals that are still suckling. They help the young animal suckle milk even without lips.
It is always very sad when dead marine animal strandings are reported, but it is a huge privilege to have received the necessary training and permission to handle and sample the animal’s remains. It’s good to know that although the individual animal has been lost from the population it will at least contribute to the pool of knowledge concerning our marine species.
The scrapes and cuts on the flesh of the dolphin along with the missing eye are all inflicted after death. Some can be from the animal getting dragged about on the rocks by wave action. Other marks and the eye are caused by birds trying to gain access to a massive food supply.
The remains of these animals are generally not buried but left in a discrete spot for birds etc. to feed on. Natural recycling at work.
Not a cetacean
One final dead species was reported to the Field Club on 5th February by Jane Adrian. Not a marine species as such but an Atlantic Puffin, Fratercula arctica. Photo 6.
Jane spotted this bird on the beach at Inverkirkaig while having a wander, and because it was unusual she decided to report it.
While Puffins don’t breed in Assynt they are occasionally seen from Stoer Head Lighthouse early in the breeding season. They do breed on Handa in small numbers.
This seems to be an early returning adult bird that has probably succumbed to the recent frequent storms. It had not yet gained its breeding plumage, part of which is the brightly coloured plates on the bill that make this species such a joy to watch.
Our thanks to all those mentioned for taking the time to report these animals.
David Haines