Although there are a few thousand porpoises swimming around in the Dutch part of the North Sea, you hardly ever come across them in the Wadden Sea. This used to be different when there were large schools of fat anchovies to catch around the Wadden Islands.
Nowadays, they are occasionally spotted from the sailing ships that sail around the Wadden area. Often it is a curious loner making a side trip or having missed the turnoff. Almost never does this result in a major problem or the death of the Porpoise.
So how is it that dozens of porpoises were washed up on the beaches of Vlieland, Terschelling, Ameland and Schiermonnikoog in August 2021?
Never before have so many adult porpoises washed ashore
Even though, almost every day, a harbour porpoise washes ashore somewhere on the Dutch coast, having died from natural causes. As many as have washed ashore in 2021 is unprecedented and, their deaths were very unlikely of natural causes.
In 2011, as many as a few dozen young porpoises washed ashore scattered throughout the Dutch coast. After investigation, it was never entirely clear exactly what the cause was. It finally seemed to have something to do with their diet.
Washed up porpoises on the Dutch Wadden Islands
NU.NL berichtte over de massastranding van tientallen volwassen bruinvissen die aanspoelden op stranden aan de noordkant van Vlieland, Terschelling, Ameland en Schiermonnikoog. That they wash up here is due to a persistent strong wind that sometimes blows from the north for days.
It is noteworthy, however, that it is in a concentrated place, namely right over the Wadden Islands. However, there are exceptionally many reported by SOS Dolphin, who receive dozens of reports a day about spotted porpoises on the beaches.
Who to call if you see an animal washed up on the beach in the Netherlands
SOS Dolphin is the first agency to arrive at the scene of a report of a beached cetacean. If the animal is still alive they take care of it. Unfortunately, the reports on the porpoises during this period are without hope. SOS Dolphin can do nothing more for the animals than to ensure that they are recovered and examined.
How is it possible that so many porpoises wash ashore
That they wash up here of all places can be explained by the current and the persistent strong wind from the north. Remarkably, only adults washed ashore. Also noteworthy is that the animals are all in the same state of decomposition, indicating that they all died at the same time. This presumably has something to do with diet, disease or human activity. However, this also rules out the possibility that the animals were attacked by seals. A few possibilities may include:
1. The construction of a wind farm north of the Wadden Islands
During the wind farm construction work, the continuous monotonous noise causes the porpoise to become disoriented and eventually deaf. The Porpoise hunts by hearing and without its hearing the Porpoise is lost and dies of starvation.
This could be a plausible explanation for the sudden large numbers of dead porpoises. A very nasty and unnecessary death. There is, in fact, a technique of pile driving specifically designed for this type of job. In this process, a sleeve is placed around the pole that is driven into the seabed. Air bubbles are blown through the tube. This technology dampens the sound in such a way that life in the sea around the workplace is hardly affected, if at all.
2. Marine exercises involving shooting
Marine exercises are currently being held north of the Wadden Islands at sea. The same applies to this as to pile driving at sea. When there is extensive shooting and other forms of noise, the porpoises become disoriented and deaf and again die of starvation.
3. A deadly parasite or disease
Since it appears that the animals all died at the same time, this option is somewhat less plausible but not impossible.
They may also have eaten something in the same area that caused their deaths. Consider poisoned fish or other pollution from human hand.
As can be read on the SOS Dolphin site, porpoises were also washed ashore in Germany during the same period. Upon examination, they were found to be carrying a deadly parasite. This can be very contagious and wipe out Porpoises and other cetaceans en masse.
What is troubling, about the numbers washing ashore is that the Porpoise is not a group animal, unlike Pilot whales and Sperm whales. The latter mentioned wash up more often with several at a time.
Support SOS Dolphin
SOS Dolphin depends on private donations to be able to rescue, care for and return to the wild beached Cetaceans such as the Porpoise as well as Dolphins and other stray animals. You can help the SOS Dolphin Foundation in several ways. Check out the SOS Dolphin website and see what you can do to protect the animals around the Wadden Sea.