An unusual mortality event involving 30 sperm whales that were left stranded in the last month on the beaches along the North Sea may have finally been explained by a marine biologist.
According to Dr. Peter Evans, founder and director of the Sea Watch Foundation, all of the 30 sperm whales that met their end on coastal regions from England, Germany, France and the Netherlands probably came from the same group of juvenile males.
This bachelor pod was more than likely located near Norway’s west coast, and it was from there that the sperm whales migrated, while foraging for elusive squid.
This hypothesis is supported by necropsy results that were reported after researchers examined carcasses belonging to sperm whales found beached in the Netherlands.
Apparently, experts identified a particular type of squid in the guts of these deceased creatures, such mollusks being normally encountered in the Norwegian Trench, located in the northeastern part of the North Sea.
It may be that in search for squid the juvenile sperm whales ventured too far from their usual habitat, swimming south and eventually reaching Dogger Bank, where the North Sea is much more shallow than usual.
While the marine mammals normally prefer more unfathomable waters, with depths that can surpass 10,000 feet, in this case they ended up trapped in an incredibly shallow portion of the North Sea, where depths barely reach 164 feet, and water levels are sometimes as low as 65 feet.
Given that sperm whales rely on echolocation to search for quarry and navigate through their surroundings, they are rendered powerless in overly shallow waters, where this biosonar doesn’t function as reliably as it did in deeper regions of the sea.
As a result, they eventually swim too close to the shore, and are left stranded and completely defenseless on the beach. There, they are euthanized after rescue efforts prove in vain, or die on their own, usually because of starvation or exhaustion.
That’s exactly what’s been happening this year in the southern portion of the North Sea: so far, 6 sperm whales have been beached in Hunstanton and Skegness, along England’s east coast, and two dozen others have shared their fate in Germany, France and the Netherlands.
The hunt for squid seems to be the most likely determinant for this unusual mortality event, at least in the opinion of Dr. Peter Evans.
The marine biologist has firmly rejected other theories, which had suggested that human activities had triggered the massive stranding.
More precisely, some had claimed that offshore wind farms and underwater sonars distracted the juvenile whales from their journey.
Others had ventured to say that the forced beachings were caused by entanglement in fishing gear, or by severe trauma caused by collisions with vessels.
As Evans explained, while it may appear tempting to blame human intervention for every unfortunate event that affects wildlife, in this case such explanations aren’t actually supported by evidence.
After all, strandings involving whales and other marine mammals have been occurring for centuries, even when the human factor wasn’t as prominent as it is nowadays.
Also, the researcher believes that in fact that sperm whale population may be experiencing a resurgence after being classified as endangered for so long, and that is why so many juveniles have been spotted in the area over the last few months.
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