Posible influencia sobre el comportamiento migratorio del atún rojo (Thunnus thynnus) de las distintas estrategias de marcado electrónico utilizadas en las almadrabas y en jaulas de engorde

Abstract

The Spanish Institute of Oceanography has been carrying out diverse research projects since 1997 on stock structure and on migration patterns of bluefin tuna (Thunnus thynnus), using the method of electronic tagging of adults. The results are provided to the stock assessment process of this species that the ICCAT Scientific Committee conducts periodically. The tagging is carried out in traps and fattening cages, observing marked differences in the movements of tunas that were tagged in the water from those that were brought on board for tagging. In the latter case, differences were also observed in the behavior of tunas that were released outside the codend of the trap from those that were released together with the rest of the shoal that was in the trap. With regard to the tagging and release of tunas in the fattening cages, it was observed that the behavior after tagging is related to time the tunas spent in the farming installations. The conclusion was reached that this type of tagging affects the natural behavior of bluefin tuna in the first phase, after which they continue with their normal biological cycle and their return to the natural habitat.