IMIS

In 1930-1950, bluefin tuna were commercially fished in Denmark and Sweden. Landings were several hundred tonnes per year, with a peak of 2000t in Sweden in 1942. Fishing continued in the next two decades and then it gradually disappeared. Sport fishing for bluefin tuna in the Kattegat and the Sound continued until the 1960s. But then, bluefin tuna catches became increasingly rare. After decades of absence, bluefin tuna have recently been sighted again in the Northeastern Atlantic, inter alia off the coast of Bohuslän and in the Skagerrak and Kattegat. In 2016 and 2017, large schools of several hundred large individuals were observed. These adult fish hunted mackerel and herring during late summer and autumn. The reasons for the return and origin of the bluefin tuna in the North Sea-Skagerrak-Kattegat are unknown. This project will use electronic tags to help understand its migration patterns and behavior, avoid unwanted bycatch and support sustainable management of the stock. Attaching long life acoustic tags holds the potential to observe transatlantic migration as well as repeatability of the migratory pattern, by using the OTN network of receivers.