The touching story of a lonely dolphin in the Baltic Sea

A team of marine biologists at the University of Southern Denmark has discovered a lone bottlenose dolphin (Tursiops truncatus) living in the Baltic Sea.

What's special is that he seems to be 'talking' to himself. In the study published in the journal Bioacoustics, the research team analyzed thousands of sounds made by the dolphin and discovered interesting things about this lonely creature.

Journey to a strange sea

Five years ago, residents living along the Svendborgsund Canal in the Baltic Sea, Denmark, were surprised to notice the appearance of a lone male bottlenose dolphin. He seemed to have made the canal his home. This was a rare discovery, as bottlenose dolphins usually live in groups and are not often seen in this sea area.

The locals quickly named the fish Delle . Delle's appearance caught the attention of scientists, who were curious as to why a dolphin would choose to live alone in an unfamiliar place. They noted that Delle did not appear to befriend the local harbor porpoises, a small species of dolphin that normally inhabits the area.

Delle's dolphins make sounds that are often associated with aggressive behavior in dolphins. (Illustration photo).

Sounds of Solitude

To learn more about Delle, the researchers placed underwater recording devices to see how the presence of a solitary dolphin affected the harbor porpoise. They were shocked to hear Delle making so many noises. " Out of curiosity, I decided to add an acoustic recorder to record the actual sounds," lead author Olga Filatova, a dolphin biologist at the University of Southern Denmark, told Live Science in an email. "I thought we might pick up a few distant whistles or something. I certainly didn't expect to record thousands of different sounds."

The discovery surprised the research team: over 69 days from December 8, 2022 to February 14, 2023, the team recorded 10,833 different sounds that Delle emitted.

Through analysis, the team found that Delle made a variety of sounds, from clicks and whistles to sounds typically associated with aggressive behavior in dolphins. Notably, these included sounds commonly used for communication between dolphins, a sign that Delle was talking to himself. Delle also made low-frequency sounds and tapping sounds, which are thought to help him navigate and find food.

Theories about 'conversation'

At first, scientists wondered if the dolphin was trying to communicate with a local boater, and they also recorded sounds at night to see if there were any people there.

"Dolphins are very vocal animals, so it's not surprising that this individual was vocal despite being alone," Thea Taylor, executive director of the Sussex Dolphin Project, who was not involved in the study, told Live Science in an email. "Dolphins rely on sound for key activities such as hunting and sensing their environment," she added , and they also use sound to communicate from a distance.

It is worth noting that Delle continued to make these sounds even when no humans were around . This shows that he was not trying to communicate with humans but was probably comforting himself.

The team offered some emotional theories: "Perhaps Delle was displaying spontaneous emotions, like humans bursting into laughter when remembering something even when they are alone. Or perhaps he was simply lonely, and 'talking' to himself was a way to distract himself from his loneliness."

Delle's story is not only a scientific discovery, but also a gentle reminder of loneliness, a feeling that not only humans, but perhaps animals also experience. The image of Delle alone in the middle of the Baltic Sea, without friends or fellow humans, makes us think about the responsibility to protect and sympathize with the natural world.

That little dolphin, with its voice, seems to be telling a sad story about a lonely life, but at the same time is a testament to the power of survival and resilience in a challenging world.