Since the 1980s, the Atlantic bluefin tuna, also known as Thunnus thynnus, was subjected to severe overfishing, which led to a global collapse of stocks. Consequently, the International Commission for the Conservation of Atlantic Tunas (ICCAT) established fishing quotas for the Atlantic in the late 1990s. However, these quotas were not adhered to, and it is estimated that until 2008, over 50,000 tonnes of Atlantic bluefin tuna were caught annually.
Starting in 2008, ICCAT intervened and developed a 15-year recovery plan. This plan included a drastic reduction in quotas, the restriction of the fishing season depending on gear type and vessel size, and an increase in the minimum size of landed tuna from 10 kg to 30 kg.
Importantly, if left undisturbed, the Atlantic bluefin tuna reaches an average length of up to 3 metres and a weight of up to 300 kilograms. The largest recorded specimen measured over 4.50 metres and weighed over 680 kilograms.
The conservation measures proved effective. A stock assessment in 2017 indicated that the Atlantic bluefin tuna was no longer considered overfished. The IUCN Red List of Threatened Species downgraded its assessment from "Near Threatened" to "Least Concern". A notable success in marine conservation.
Regarding the killer whales (Orcinus orca), their involvement began in 2020: around Gibraltar and southwestern Spain, they suddenly began targeting sailing yachts. They ram the rudders, disabling the vessels' steering. Over the past five years, approximately 700 vessels have been affected, and several have sunk.
For a long time, the cause of this new behaviour remained unclear. Experts are now certain: the killer whales have leisure time, as the preferred prey of the "Iberian killer whales"—a subpopulation of 25 individuals—is the Atlantic bluefin tuna, which has become abundant once again. Consequently, the killer whales no longer need to spend the entire day foraging, resulting in spare time which they utilise to display play behaviour. They have now also begun transmitting this behaviour to their offspring. The Spanish government has therefore warned mariners of specific sea areas where killer whale activity is particularly high.
Overall, these findings represent positive ecological developments.
