The unusual case of the Scrabster humpback….
On Thursday 30th May the Scottish Marine Animal Stranding Scheme (SMASS) team travelled north to perform a necropsy on yet another entangled whale, which was first spotted by a local fisherman floating at sea earlier in the week. This was a humpback whale (Megaptera novaeangliae), which stranded on Scrabster beach, Caithness.
The young humpback whale washed ashore on Scrabster beach. Image credits: Gavin Bird
A juvenile male, this case stranded wrapped in creel rope attached to a buoy, with rope encircling the pectoral fins pinning the left fin tightly to the body wall. This had caused significant rope lacerations to both fin margins and there were large amounts of liquid in both stomach and lungs, providing evidence the animal had likely drowned. Unusually, the gear removed from this animal did not come from the Scottish fleet and has been traced to a Nova Scotia lobster fishery, some 2500 miles away! We were able to make contact with the fisher and make him aware of this incident. He was devastated to hear about this much like all the other fishers the SEA programme have worked with who have encountered an entanglement, but he was very helpful and provided valuable information pertaining to this case which we could not have gained any other way.
This case does raise some very interesting questions – the animal was in moderate to good body condition, had evidence that it had fed reasonably recently and, in contrast to the previous humpback we reported last month near Dunbar, did not show signs of long term debilitation. In addition, the wounds associated with the rope were reasonably recent, with limited scarring and tissue remodelling, and there were marks around the tailstock and fluke made by different ropes which were no longer attached to the animal. It’s possible therefore that this was a two-stage entanglement as the pattern of skin abrasions around the tailstock and fluke suggest the animal had also been acutely entangled, but these ropes which became detached or were removed prior to the animal stranding. But where did this animal first became entangled? Did it entrain gear in the waters off Nova Scotia and drag the buoy across the Atlantic, or was the buoy ‘ghost gear’ which drifted across the Atlantic and entangled the animal off the coast of Scotland? We suspect the latter is more plausible based on the pathology, and also it is unlikely that a young animal like this would swim between both sides of the Atlantic. We may never know but with the help of fishermen, researchers and volunteers from Scotland, Canada and the USA we have been able to better our understanding of entanglements and highlighted that marine debris and ghost gear are genuinely a global hazard, whose impact spans ocean basins, sometimes affecting marine life many thousands of miles from where originally deployed.
Some of the injuries sustained by this humpback as a result of becoming entangled. Image credits: SMASS
We say this a lot, but please remember that no entanglement is deliberate, and understanding how to reduce and mitigate the risk to marine wildlife needs engagement from the fishing community- they are the solution to this issue, not the problem. In this and other cases we have reported on in recent weeks, the fishing community have played a vital role in allowing us to better understand how and why these incidents occur, and how these may be prevented in the future.