Ten porpoises wash up on Fredericia beach, marine biologist links to local dolphin

Bjarne Christensen, a nature guide in Fredericia Municipality, walks along Sandal Strand to examine a porpoise that washed ashore a week ago. The dead porpoise has had its eyes eaten by seagulls, which prefer the soft parts. Shortly after, he spots another porpoise just 10 meters further down the beach. This one appears fresh, suggesting it washed up that morning.

“This is actually the most beautiful one I’ve seen. It’s one you might consider taxidermying,” he comments, although it will instead be sent to Aarhus University for a post-mortem examination to determine the cause of death. This marks the tenth porpoise carcass to wash up in Fredericia Municipality over the past 14 days, a significant increase from the typical four to six reports received annually.

Identifying the cause of the surge in dead porpoises is challenging, but Christensen suspects a dolphin known as Skywalker, which has been in the area for most of the summer. “We have evidence that Skywalker has killed at least one porpoise,” he notes, explaining that some carcasses show signs of physical trauma from encounters with the dolphin.

While it’s not unusual for dolphins to kill porpoises, the reasons behind their behavior remain puzzling. According to marine biologist Ditte Bølle Jespersen, Skywalker may be acting out due to unmet social needs, as he lacks a nearby pod of females or competitive males. She emphasizes that porpoises and dolphins are not natural enemies, often feeding on different prey.

Fredericia officials are not planning immediate action regarding the stranded porpoises, as Christensen views the situation as part of nature’s cycle. “We may never know how many of these porpoises Skywalker is responsible for, but it’s natural for porpoises to occasionally die in Lillebælt,” he concludes.