Long-finned pilot whales are a pretty rare sight in Dutch waters. In over 400 years, there have only been 17 strandings on the coast of The Netherlands. However, in the space of just one month, two of these pilot whales washed up onto the country's beaches. The curious case became even more odd when it became clear both had died choking on common sole fish.
A team lead by Lonneke IJsseldijk, Cetacean Project Coordinator at Utrecht University’s Faculty of Veterinary Medicine, studied both the cases of this cetacean murder mystery and published the findings in the journal PLOS ONE.
The first pilot whale was found on December 17, 2014 on the beach of Nieuw-Haamstede with a common sole lodged in its nasal cavity. As Earth Touch News reported, scientists were initially skeptical that the fish had caused asphyxiation. Firstly, there were no recorded cases of pilot whales choking on fish. Secondly, there’s only one record of pilot whales feeding on these specific fish. While IJsseldijk and her team were convinced the sole had choked the pilot whale, her peers seemed to think its presence was just a freak accident.
However, four weeks later, a 4.5 meter (14.7 foot) pilot whale washed up near Petten with a common sole protruding mid-escape from its blowhole. After performing a necropsy, it became clear that the fish had blocked the pilot whale’s airway and choked it to death.
Image A: Sole's tail hanging out of second pilot whale's blowhole. Image B: Blowhole, cut open, of the same pilot whale. The white arrow indicates the left side of the blowhole opening, while the red arrow indicates the fish’s tail in both images. Image credit: Lonneke L. IJsseldijk
But what was the fish doing in there?
Pilot whales are usually found in North Atlantic waters, but there were numerous sightings of pilot whales across the south coast of England and Belgium in the previous month. For whatever reason they were there, they were a long way from home, and their normal prey.
IJsseldijk believes that hunger forced the pilot whales to eat the common soles. However, this prey is a lot larger than their usual food of choice like squid and small fish. To try and swallow this overly ambitious mouthful, the pilot whales relaxed the muscles separating their airway and digestive tract. This allowed the super-flexible, wriggly common sole to make its way into the airway passage in a desperate attempt to escape. All in all, it sounds like a bad time for all parties involved.