PHOTOS: Vinko the dolphin becomes first in Adriatic Sea tagged with satellite transmitter

Vinko the dolphin (Photo: Copyright – Institut Plavi svijet 2025)

In a major milestone for marine research in Croatia, scientists from the Blue World Institute and the Croatian Natural History Museum have successfully tagged a bottlenose dolphin with a satellite transmitter for the first time in the Adriatic Sea.

The male dolphin, known as Vinko, was tagged on 15 June 2025 just a few kilometres from Veli Lošinj in the Lošinj Archipelago.

Born in 2015, Vinko is a familiar figure to researchers and was first spotted as a playful calf leaping near a research boat in 2016.

He is easily recognisable by the hook-shaped tip of his dorsal fin, shaped over time through playful encounters and interactions with other dolphins.

“Vinko was in a group of eight dolphins near the islet of Oruda when we tagged him,” explained Jeroen Hofs from the Blue World Institute. “He was active, socialising and playfully nudging Luca’s20, a young female he has often been seen with over the years.”

Vinko the dolphin with his mum in 2026 (Photo: Copyright – Institut Plavi svijet 2025)

Soon after the transmitter was attached to Vinko’s dorsal fin, researchers received the first location signal, confirming that the device was functioning properly.

“We stayed with the group for about an hour after tagging to observe Vinko’s behaviour,” said Dr Grgur Pleslić, Director of the Blue World Institute’s Scientific Programme. “He behaved normally—swimming with the group and interacting as usual—though he was initially slightly wary of us.”

Tracking Movement in a New Way

The tagging is part of the Blue World Institute’s new satellite telemetry study, the first of its kind in the Adriatic. For over 35 years, the Institute’s Adriatic Dolphin Project has monitored local dolphin populations through photo-identification—matching dorsal fin photographs to track individual animals. While highly effective for monitoring social groups and estimating population numbers, this method doesn’t provide detailed information about movement patterns or habitat use.

Vinko the dolphin with a satellite transmitter (Photo: Copyright – Institut Plavi svijet 2025)

“With satellite tracking, we aim to gain new insights into the dolphins’ behaviour, including their nocturnal activity, feeding strategies, and interactions with fisheries,” said Dr Draško Holcer, museum advisor at the Croatian Natural History Museum and head of the study. “These findings will help shape future research and conservation efforts.”

On 17 June, researchers located Vinko again—this time in the Velebit Channel—where he was swimming close to the research boat and diving underneath it, confirming both he and the transmitter were in good condition. He was now part of a larger group of 11 dolphins.

How the Satellite Tag Works

The satellite transmitter used is a small, minimally invasive device known as a LIMPET (Low Impact Minimally Percutaneous Electronic Transmitter). It is attached to the dolphin’s dorsal fin using titanium darts and sends location data to the Argos satellite system whenever the fin surfaces.

The tag remains attached for around 15 to 30 days before naturally falling off. Researchers use a modified crossbow to carefully deploy the tag, ensuring the process is as gentle as possible.

Vinko the dolphin with his mum in 2026 (Photo: Copyright – Institut Plavi svijet 2025)

Citizen Science: Public Invited to Help

The team is calling on the public to support the study by reporting dolphin sightings in the Kvarnerić area.

If you spot Vinko or his companions, you can submit photos or videos with the exact time and location through the Marine Ranger app (available on the App Store and Google Play), by email at [email protected], or via the Blue World Institute’s Facebook page.

Public contributions can significantly enhance the data collected via satellite, helping scientists paint a fuller picture of dolphin movement and behaviour.

Interestingly, Vinko had already been reported through the Marine Ranger app last year, when he was seen off the coast of Crikvenica.

Vinko the dolphin in the company of other dolphins (Photo: Copyright – Institut Plavi svijet 2025)

International Support and Project Partners

This groundbreaking study is the result of years of collaboration and training with Italian partners from the CIMA Research Foundation in Savona and ISPRA, the Institute for Environmental Protection and Research in Rome.

The tagging was carried out with permission from the Croatian Ministry of Environmental Protection and Green Transition.

The Blue World Institute, based on the island of Lošinj, is a leading Croatian NGO focused on the research and protection of marine life across the Adriatic. Its work spans dolphins, whales, sea turtles, monk seals, sharks, and rays, and aims to foster public awareness and sustainable marine conservation.

The Croatian Natural History Museum is the country’s national institution for natural sciences, dedicated to collecting, preserving, and studying Croatia’s rich biodiversity, while also promoting education and scientific research for conservation.

As satellite signals from Vinko begin to paint a new picture of life beneath the Adriatic waves, researchers are hopeful this marks the beginning of a new era in dolphin science—and marine protection—in Croatia.