Acoustic tag sheds light on migratory journey of bluefish

ISTANBUL

In a bid to protect biodiversity and promote sustainable stock management, Turkish officials have begun monitoring the migratory path of bluefish using acoustic telemetry.

The initiative is a part of the international Strategic Infrastructure for Improved Animal Tracking in European Seas (STRAITS) project, which aims at monitoring aquatic life throughout Europe and preserving biodiversity.

Associate Professor Dr. Aytaç Özgül from Ege University’s Faculty of Fisheries, the project representative in Türkiye, and his team carried out the tagging process of bluefish, the iconic symbol of the Bosphorus.

As part of the study, they anesthetized a total of 10 bluefish in a specially designed tank, placing the acoustic telemetries in the abdominal cavities of the fish.

“We use acoustic telemetries to label the fish we obtain from our fishermen before releasing them back into the sea. We wish to ascertain the path taken by our fish in the event they are not captured and continue on their journey,” Özgül explained.

Referring to the surgical procedure, he underlined that they work meticulously not to cause significant harm to the fish.

"The fish may continue swimming and migrating with the tag it bears, as we ensure minimal harm," Özgül said. "In our previous research, we were able to track those fish even a year later."

Özgül noted that each of the 25 acoustic telemetry devices placed along the coast has a coverage area of approximately 500 meters. The receiver detects the signal emitted by the fish as they pass through this area, allowing for the tracking of the amount of time the fish spend at each location.

He explained that as the project aims to identify the bluefish's migration path and the duration it spends in each region, the data will enable relevant institutions to better manage sustainable fishing practices for bluefish.

Pointing out that more data can only be gathered by tagging more bluefish, Özgül urged fishermen to release the fish equipped with acoustic transmitters back into the sea after capture.