Atlantic bluefin tuna have recolonised waters off northeast England for the first time in 60 years - and a team of University of Exeter researchers have tagged these iconic fish for the first time ever.
In the 1930s Scarborough was a globally famous destination for big game fishing, with Hollywood stars John Wayne, Clark Gable and Errol Flynn among the celebrities who flocked to the Yorkshire coast to catch giant bluefin tuna. However, by the 1960s the fish had disappeared from the North Sea due to overfishing and the depletion of herring shoals.
Now bluefin tuna have returned, and the Exeter team has successfully tagged five off the coast of Whitby, with more tags to deploy this week. Tagging is essential for understanding the bluefin's migration patterns, origins, and for informing international conservation and fishery management, particularly in relation to which country the fish belong to.
Dr Lucy Hawkes, of the University of Exeter, is leading the research and said: "Bluefin tuna is a native British species. They are supposed to be in our waters and used to be incredibly important to this region. The fact they're back has been thanks to some careful and judicious management of fisheries.
"Bluefin tuna are also top predators who can only be in these waters if the ecosystems underneath them are healthy. Essentially their presence is a good way of signalling your waters are doing well, but we have no idea where they've come from - which is why tagging is so important."
The team has eight tags in total, with each sitting on the fish for two years. They record light, temperature, and depth, which allows researchers to estimate the bluefin's location. The tag is programmed to detach after a set period, floating to the surface to transmit summary data via satellite. Physically recovering the tag then provides access to even more detailed data.
There is currently no data for the bluefin tuna in the waters off northeast England, so tagging is essential to promote effective evidence-based management, and to contribute to international conservation planning for bluefin.
The International Commission for the Conservation of Atlantic Tuna (ICCAT) manages quotas for bluefin tuna across the Atlantic, and accurate tagging data is necessary for ICCAT to allocate quotas fairly among countries based on the true origins and movements of the fish.
Since 2018, Exeter's team of researchers have tagged 165 bluefin tuna from the southwest coast of England, Wales and Jersey. However, these fish found off the northeast coast are considerably larger and may be genetically distinct from those already tagged.
Tagging data has previously revealed migration routes into the Mediterranean for spawning, the timing of arrivals and departures in the English Channel, and evidence that bluefin tuna may breed later and less frequently than previously assumed by ICCAT.
