The Delphinus delphis, an uncommon dolphin species, has been repeatedly spotted in the Adriatic Sea. According to recent research led by marine scientists at the University of St Andrews, the rare dolphin has been observed multiple times off the coasts of Italy and Slovenia. The research was done in collaboration with Morigenos Slovenian Marine Mammal Society with a goal to determine the occurrence of common dolphins in the Gulf of Trieste and the Northern Adriatic Sea. The findings of the study, published in the journal Aquatic Conservation: Marine and Freshwater Ecosystems, came as a shock to many scientists, given that Delphinus delphis was considered regionally extinct in the Adriatic Sea.

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The decline in Delphinus delphis numbers in the Adriatic Sea can be traced back to misinformed policies put in place by Italy and former Yugoslavia in the mid-20th century. At the time, this species of dolphin was considered a pest to the fishing industry. The two countries encouraged people to kill these dolphins for monetary reward to reduce competition for fish. In the 1970s, the number of Delphinus delphis dropped significantly, leading to the species being listed as endangered on the IUCN Red List. Besides the direct killing of the species, increased fishing activities have also led to a reduction in the number of dolphins in the Adriatic Sea.

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Over the past 30 years, Delphinus delphis have been very rare in this area, leading to speculations that they might be regionally extinct. However, the recent findings show that Delphinus delphis are showing up more regularly, with four animals spotted repeatedly over a 4-year span. The research, conducted through photo-identification, also shows that some of the dolphins spotted in the Adriatic Sea had traveled as far as 1,000 kilometers.

“Unfortunately, the species continues to be rare in the region. It is difficult to say if the species is likely to make a comeback to the Adriatic Sea,” said Tilen Genov, leader of the research team and member of the Sea Mammal Research Unit for University of St Andrews. “The chances for that are likely slim, as there is currently no evidence of any increase in common dolphin abundance or sightings anywhere in the Mediterranean Sea. But hopefully, this contribution can serve as a baseline and encourage potential future cases to be reported, in order to provide further insights into the occurrence of common dolphins in the region.”

+ Aquatic Conservation: Marine and Freshwater Ecosystems

Image via University of St Andrews