When science engages sport fishers to improve knowledge of bluefin tuna ( Thunnus thynnus ), the synergy is perfect. What better method than angling to dry quickly and in good conditions a bluefin tuna in order to place an electronic tag to follow its movements?
Before getting into the heart of the matter in a future article, let's go back to the interest of electronic markings.
What is the electronic tag?
It is an electronic tag. The latter is inserted on the back of the fish and records its movements for up to 10 months. When the battery gets too low, the tag is detached and goes to the surface to pick up satellites and transmit the recorded data via the Argos system. This system collects data dedicated to the study and protection of the environment as well as maritime safety. The data is then received by scientists, in this case Ifremer, who trace the path taken by the fish studied from the moment the tag is placed until it is brought to the surface. Among the data, we also find the water temperature, the pressure (thus the depth to which the fish descends) or the light (which gives data on the location)...
Sometimes the tag detaches itself through wear and tear, sometimes the fish is captured and the tag can be given away, the Holy Grail for scientists who can exploit all the data without loss.
Why these Ifremer studies?
These electronic tagging campaigns for bluefin tuna are not new. They lead to a better knowledge of the species in order to control the professional fishing of this fish. Bluefin tuna is under strong fishing pressure worldwide. The demand is there, it is consumed with passion everywhere in the world in the form of sushi or sashimi.
Thanks to these studies, ICCAT (International Commission for the Conservation of Atlantic Tunas) prepares scientific advice to better manage the stocks. The European Union follows these recommendations to set quotas, from which the number of rings allocated to recreational fishermen is determined.
