Researchers have said that bottlenose dolphins living around the tourist hotspot of Ibiza are highly sedentary occupying small areas of the sea where they get to know their neighbourhood and even make friends with fishermen.
They have even found one male common bottlenose dolphin (Tursiops truncatus) that they believe has occupied the same region for 11 years, who has been named Thinfin because if his unusual looking flippers.
It is also the helpful characteristic that allowed him to be identified in sightings a decade apart in the same waters of Ibiza, in the eastern Spanish region of the Balearic Islands.
Txema Brotons, the scientific director of the association Tursiops, explained to Real Press that back in 2009 when he was conducting some research, he spotted a dolphin with a distinctive flipper that had marks on it and he found out thanks to a biopsy that it was a male dolphin.
Eleven years later, in 2020, the expert saw it again in the Ibiza waters. Brotons said: “Dolphins in the Balearic Islands presents a high grade of sedentary lifestyle and their geographical stability is very important.”
According to the researcher, the dolphins are “cultural animals, like human beings, because they can learn and even teach things, and they have learned how to live with fishermen in Ibiza.”
Brotons also explained that a group of dolphins can identify a very profitable way of feeding and they take advantage of it. If a dolphin knows that in a specific area of the islands they can find food in an easy way, they tend to stay longer and even teach other dolphins how to find the food too.
In fact, the researcher commented that “some of the learnings have spread”, and added that for example, there were dolphins living in northern Majorca, also in the Balearic Islands, interacting with fishermen to feed, and “that interaction expanded to the western area and other individuals learned how to do it or other dolphins taught them.”
The researcher also said that it is believed that the dolphins can identify and even recognise individual fishing boats based on the noise they make.
The expert have been studying the dolphins’ behaviour as part of a project called “Nuestros Delfines” (Our Dolphins), which includes the use of hydrophones, which are a kind of underwater microphone, which they have set up in the waters around Ibiza.
The microphones have so far managed to identify 51 different common bottlenose dolphins.
During the research, as well as confirming the dolphins’ sedentary lifestyle, it was also confirmed that during the lockdown due to the coronavirus crisis, the acoustic pollution decreased by almost half in the waters of Sant Josep, around the island of Ibiza.
The lockdown and the decrease of boats sailing in the area reduced the noise average by almost three decibels.
However, according to Brotons, the noise situation in the Islands would have been better if the lockdown had happened during the summer season, as the lockdown took place during winter and early spring, when there are more storms in the waters around the islands and there is less tourism.
Brotons added: “The natural noise in winter is very important because there are storms”.
According to the director of the association, the noise could affect the dolphins a lot, as well as other mammals in the area, as they are “very acoustic animals”.
In fact, Brotons explained that some noises “could kill dolphins, especially if they are close enough”, let alone “injure them physically”.
The noise can also cause problems with their communication, as “they have to shout and it is more difficult for them to find food, as they cannot hear nearby sounds as much.”