In 2019, a sushi businessman bought an incredible $3.1 million for bluefin tuna at a Tokyo auction. A tuna weighing 278 kg (612 lbs) which is equivalent to the weight of a grizzly bear was the most costly fish ever put up for sale.
According to Sarah Glaser who is a senior director of the oceans futures team at the World Wide Fund for Nature (WWF) US, bluefin which is usually used in sushi and sashimi is the most costly fish in the world and tuna is the most commercially valuable family of fish worldwide.
Skipjack is the smallest and most common type of tuna and a single bluefin can bring over a tonne with it. Bluefin supplies have been drastically reduced putting the species in danger of going extinct in 2010 due to overfishing and the enormous demand for sushi around the world.
In recent years, bluefin tuna populations have increased significantly as countries implemented more sustainable fishing regulations and cracked down on illegal fishing. But climate change has become an important challenge for bluefin tuna. According to studies, bluefin tuna are extremely sensitive to temperature variations and even slight rises can have an impact on their feeding, mating and metabolism. Scientists caution that fishing communities and other marine species may be impacted by the changes happening to bluefin tuna.
Bluefin tuna, which is the largest tuna in the world measures to 6 -10 feet (1.8-3 meters). They are top predators that hunt schools of fish such as herring and mackerel by sight and have a lifespan of up to 40 years. Among the world’s quickest swimmers are the warm-blooded fish like Bluefin tuna. Each year, they travel thousands of miles to hunt and spawn. But these patterns of migration are already beginning to change.
Bluefin tuna are migrating to colder waters as ocean temperatures rise. According to the study, tuna feeding sites may move to cooler locations like the Bay of Biscay and young tuna may wind up in sardine and anchovy fisheries, this migration presents a new problem. It is mentioned that anything over 28 degrees Celsius will impact bluefin’s growth as well. The study predicts that during the next 50 years, the Mediterranean Sea will warm to a point where juvenile bluefin tuna may completely go away.
It is also said in a different study that they saw bluefin tuna feeding in unusual areas, for example in the North Sea around Scandinavia and Iceland. They are already witnessing changes in migration patterns.
