SMASS – two recent entanglement cases Sept/Oct 2024
Two recent examples of the ongoing issue of marine entanglements were reported to the Scottish Marine Animal Stranding Scheme (SMASS) team last week. The first was a 9.60m long female humpback whale which washed ashore in Granton, Edinburgh on the 29th September. This whale had several skin abrasions highly consistent with rope entanglements. A week later and 100 miles north, a 5.75m long female minke whale washed ashore in Johnshaven on the Aberdeenshire coast. Due to issues with access and disposal, we weren’t able to do a full necropsy on either case, however thanks to the help of SMASS volunteers, we have tissue samples, measurements and detailed images of both animals and are confident that entanglement was the most likely cause of death.
Image 1: The humpback whale ashore in Granton. Image 2: The minke whale 100 miles north at Johnshaven.
Both of these were sub-adult animals in moderate body condition, suggesting they had been successfully feeding prior to becoming entangled. The humpback whale had bruising and abrasions across the throat pleats and around the pectoral fin consistent with some sort of rope. The minke whale had much more obvious signs of entanglement, with a deep encircling laceration around the tailstock and twin linear lesions on the underside of the fluke consistent with a rope which was under tension and had dug so far into the into the tissue it had almost amputated the fluke, most likely whilst the animal was still alive. As we often find, neither whale stranded with any material remaining attached, meaning it is not possible to say if this was active fishing gear, marine debris or rope from a non- marine source. This also highlights the significant welfare and conservation issues caused by entanglement around Scotland.
Image 3: bruising and abrasions visible on the humpback whale’s throat pleats and around the pectoral fin appear consistent with some sort of rope.
Image 4 and 5: Deep tissue injuries to the minke whale’s tail.
Entanglement is the most commonly diagnosed cause of death in both minke and humpback whales in Scottish waters and these two cases take the total number of entanglement reports received by SMASS this year to twelve (other species reported entangled this year include grey seals and basking sharks). Past studies have estimated that up to 95% of cases go unreported however, so the true figure is likely much higher. Cetacean and shark entanglement is a growing concern globally, but SMASS are taking positive steps towards reducing this threat in our inshore waters as a partner in the Scottish Entanglement Alliance (SEA).
SEA continue to work closely with the fishing industry to better understand the scale and impacts of entanglement, and to trial practical mitigation measures to protect both our marine wildlife and our small-scale fisheries. Read about a recent project here.
We have recently received funding to start two new fisherman-led projects – updates to follow soon!
Special thanks to Georg Hantke from the NMS, and Christoph Gade and Roma Banga from our trained volunteer network, for their help in documenting and sampling these cases on behalf of SMASS.
Image 6: The humpback whale being removed from the beach.