6,370 kilometres across the Atlantic Ocean. That is the vast distance, as the crow flies, which has been covered by an albacore tuna tagged and released into the sea off a Gipuzkoan locality, 20 km to the north of Donostia-San Sebastian in October 2006. The specimen has recently been caught by Venezuelan fishermen just off the coast of their country. This is a record distance covered by an albacore tuna among those registered by the ICCAT-The International Commission for the Conservation of Atlantic Tunas. When the specimen was tagged, it was a year old, 50 cm long and weighed 2.5 kg. When it was recaptured six and a half years later it weighed 21.8 kg and measured 100 cm. Tuna tagging is routine practice to find out, among other things, about their migrations and how big the populations of these species are.
This record bonito was tagged by the fisherman Fernando Zapirain aboard the vessel Kutxi Kutxi, whose home port is in Hondarribia (Basque Country), in the course of a sports tagging championship, in which nearly a thousand specimens with tags belonging to the AZTI-Tecnalia R&D centre were released into the sea. The albacore tuna has been recaptured by professional fishermen aboard the vessel Black Marlin; they handed the specimen over to the Oceanographic Institute of Venezuela, which informed AZTI-Tecnalia researchers about the find. The latter, in turn, passed the data onto the ICCAT, a body that undertakes to centralise all the information concerning the tagging of tuna and similar species in the Atlantic Ocean and the Mediterranean Sea.
There are very few records of albacore tuna (Thunnus alalunga) crossing the Atlantic ocean. The albacore tuna caught off Venezuela is the one that has covered the greatest distance and also the one that has been found at the southernmost point, in its reproduction area in the North Atlantic. It has also been one of the longest-lasting records, since the specimen was recaptured six and a half years after it had been tagged and released, a little less than the nearly 8 years that the longest record took.
The conventional tag the albacore tuna was carrying was attached to its second dorsal fin and bore the contact details of AZTI-Tecnalia plus an identification code. The purpose of tagging tuna is to obtain information about their movements and migrations, stock structure, growth, population size and physiology. This information enables experts to analyse the repercussions that the various types of fishing are having on this species.
Specimen found in Massachusetts
In 2007 there was a similar case when a sports fisherman from Massachusetts (USA) caught a Bluefin tuna that had been tagged and released into the sea off Hondarribia. The animal had covered a distance of 6,170 km, as the crow flies. In the current case the tuna had covered a greater distance than the one found in the USA; and the record albacore tuna turned up in a latitude much further south than the one found in the USA, which was located in a latitude similar to that of the Bay of Biscay. The specimen released in Hondarribia had remained at sea two years and two months until it was recaptured, as opposed to the six and a half years that it took to recapture the current tagged specimen.
Collaboration between sport fishermen and researchers
Tagging campaigns started in the Basque Country back in 2001 and both professional and sport fishermen have been participating in them. The greatest boost to this activity was made eight years ago when the Government of the Basque Autonomous Community supported a collaboration agreement between the Nautical and Recreational Fishing Associations of the Basque Country and the R&D Centre AZTI-Tecnalia, which specialises in marine and foodstuff research.
Since the signing of the agreement, many recreational vessels have tagged thousands of specimens of albacore, bluefin, bigeye and skipjack tuna. AZTI-Tecnalia experts regard the collaboration with recreational fishermen, who receive training in how to handle the tags and the fish during tagging, as essential for the tagging and notifying of the captures of tagged specimens.
Biological details about the species to which the albacore tuna recaptured off Venezuela belongs:
Common name: albacore tuna, albacore fish, Aαhi Taria, Bastard Albacore, Bonito, langvin tuna, long-finned tuna, longfin tuna, long-fin tunny, longfin tunny, tuna, albacore.
Scientific name: Thunnus alalunga (Bonaterre, 1788).
Distribution area: cosmopolitan, in all oceans, in tropical and temperate waters. Fishing fleet/fishing gear: live bait, trolling, pelagic trawl, longline.
Habitat: surface and deep ocean waters.
Temperature: between 9.5 and 23Ί C. Thermal fronts appear to determine their spatial distribution as well as their topography (they tend to be found in ocean waters outside the continental platform).
Maximum size: 140 cm. Most of the ones caught in the Bay of Biscay measure between 50 and 110 cm. Maximum weight: 45 kg. Predators: sharks, whales, swordfish, other tuna species. Diet: fish (blue whiting, saury, anchovy, etc.), planktonic crustaceans (krill, amphipoda, etc.), and cephalopods.
Reproduction: multiple spawners. The Atlantic populations spawn in the Sargasso Sea and in ocean waters off the Venezuelan coast.
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