Their torpedo-shaped, streamlined bodies are built for speed and endurance. Their coloring—metallic blue on top and shimmering silver-white on the bottom—helps camouflage them from above and below. And their voracious appetite and varied diet pushes their average size to a whopping 6.
Unfortunately for the species however, bluefin meat also happens to be regarded as surpassingly delicious, particularly among sashimi eaters, and overfishing throughout their range has driven their numbers to critically low levels. Atlantic bluefins are warm-blooded, a rare trait among fish, and are comfortable in the cold waters off Newfoundland and Iceland, as well as the tropical waters of the Gulf of Mexico and the Mediterranean Sea, where they go each year to spawn.
They are among the most ambitiously migratory of all fish, and some tagged specimens have been tracked swimming from North American to European waters several times a year. They are prized among sport fishers for their fight and speed, shooting through the water with their powerful, crescent-shaped tails up to 43 miles per hour.
They can retract their dorsal and pectoral fins into slots to reduce drag. Bluefins attain their enormous size by gorging themselves almost constantly on smaller fish, crustaceans, squid, and eels.
They will also filter-feed on zooplankton and other small organisms and have even been observed eating kelp. The largest tuna ever recorded was an Atlantic bluefin caught off Nova Scotia that weighed 1, pounds.
Bluefin tuna have been eaten by humans for centuries. However, in the s, demand and prices for large bluefins soared worldwide, particularly in Japan, and commercial fishing operations found new ways to find and catch these sleek giants. As a result, bluefin stocks, especially of large, breeding-age fish, have plummeted, and international conservation efforts have led to curbs on commercial takes. Nevertheless, at least one group says illegal fishing in Europe has pushed the Atlantic bluefin populations there to the brink of extinction.
All rights reserved. Common Name: Atlantic bluefin tuna. Scientific Name: Thunnus thynnus. Type: Fish. Diet: Carnivore. Group Name: School. Size: 6. Weight: pounds. Size relative to a 6-ft man:. Least concern. Least Concern Extinct. Current Population Trend: Decreasing. Here we answer some of the most common questions about tuna.
If you want to eat tuna try to limit your purchases to MSC labelled products. MSC labelled albacore and yellowfin tuna are also available in many supermarkets around the world. We eat 5 main species of tuna : albacore, bigeye, bluefin, skipjack and yellowfin. Most cans of tuna have skipjack inside. It depends on the species and if they are juveniles or adults. Skipjack tuna are the smallest and most abundant tuna, growing to about 1m in length by two years old.
Adult yellowfin and bigeye tuna are about the same size, between cms, with yellowfin becoming fully grown by 2 years old and bigeye reaching maturity at around 3 years old. Albacore grow more slowly than these three tunas, reaching maturity at around 5 years old when they are on average 1m long. The biggest tuna is the bluefin which can measure as much as 2 metres in length, nose-to-fin. In their first 6 months bluefin tuna grow from an egg to around cm in length and weighing in at 1 kg, and can take years to reach adulthood.
The biggest bluefin ever recorded was almost 2 metres long. Tuna can be found in most areas of the ocean, and can travel thousands of miles in a year. In some areas, several different types of tuna form schools with other types of fish.
For example, skipjack are found in large schools with yellowfin and bigeye tuna as well as other types of fish and marine life. Tuna also have preferences for different layers of the ocean. During the day Skipjack are found deep underwater, moving up closer to the surface at night. Albacore tend to be found at around ms below the surface, and because bigeye live in deeper depths than skipjack or yellowfin they have a deep layer of fat to insulate them from the colder waters. It depends on the species and what stage of life it is at.
Adult bluefin tuna are apex predators: they're at the top of the food chain and eat a wide range of fish. Skipjack, which are the smallest tuna, are eaten by some species of whale as well as sharks, marlin and other large fish. The tiny eggs tuna release into the sea are also food to a wide range of ocean species. German shoppers have the biggest choice of tuna from MSC certified sustainable fisheries.
In contrast, Asia has the fewest products licenced to carry the blue logo, but this is changing rapidly. In contrast, volumes of MSC labelled tuna in food service outlets fell year-on-year as did sales of pet food brands licenced to carry the MSC label on pack.
Sales of frozen tuna stayed stable. Fishing sustainably relies on scientific data that assesses how many fish there are stock status , how quickly they breed maturation rate , how many fish can be caught while making sure there are enough left in the sea to make the next generation maximum sustainable yield , and what would happen if there was a threat to the health of the stock harvest control rules.
All tuna fisheries that have met the MSC Fisheries Standard have scientific evidence that the tuna is caught from a healthy stock, is a well-managed fishery and is minimising its impact on the ecosystem. Worldwide there are 23 stocks of the major commercial tuna species: 5 skipjack, 4 yellowfin, 4 bluefin, 6 albacore, and 4 bigeye stocks. As mentioned above, some of these tuna stocks have healthy numbers and are being managed well, others are not.
Overall, the latest estimates from the UN FAO indicate the global tuna catch in was 5,, tonnes. As more tuna fisheries make a commitment to sustainability, and become certified to the MSC Fisheries Standard for sustainable fishing , a greater proportion of all the tuna caught is engaged in the MSC program.
Read more about the challenges and solutions for sustainable tuna fishing. There are different ways of catching tuna. The methods and gear used in tuna fishing could depend on:. Common gear types used by MSC certified tuna fisheries include pole and line , purse seine nets and long lines. Any of these gear types can be used sustainably, depending on their use, the amount of tuna being caught and how their gear affects the wider ecosystem.
Some tuna fisheries use additional tools like Fish Aggregating Devices FADs which have been associated with bycatch accidental catch of other species. However, these can also be well managed and FAD doesn't always mean "bad". In Japan there are tuna grades within the industry but those grades differ between regions and companies. Tuna buyers are highly skilled at assessing if a tuna meets the specifications of the sushi and sashimi chefs they supply.
They look for qualities such freshness, colour, fat content, texture, and size. But in the USA, "sushi grade" may indicate it has met a regulation that requires tuna to be flash frozen. All tuna is caught from the wild. Some tuna is caught from the wild then kept in 'fattening pens' for a while. No MSC certified tuna fisheries do this. There are three species of bluefin tuna: Atlantic, Pacific, and Southern. There are four distinct bluefin stocks and some are in better shape than others.
0コメント