![]() Despite the optimistic start to recovery, the populations continue to rely on conservation measures and have a long way to go before they are in the clear. In 2021, the International Union for Conservation of Nature (IUCN) assessments saw the Pacific bluefin move from vulnerable to near threatened, the Atlantic bluefin from endangered to least concern, and the southern bluefin from critically endangered to endangered. As tuna fishing vessels continued to return to port with empty holds, an outcry by scientists in the late 1990s and early 2000s sparked international conservation efforts, which enabled modest population increases. Atlantic bluefin were long on the endangered species list following a population crash in the 1970s, and southern bluefin were the hardest hit, earning a critically endangered designation in 1996. Scientists from the International Scientific Committee for Tuna and Tuna-like Species (ISC) estimated in a 2016 report that only 2.6 percent of the original, pre-fished Pacific bluefin tuna population remained, and in 2017 the National Oceanic and Atmospheric Administration (NOAA) estimated the population was 25 percent of what it was in the 1950s when the first population data was recorded. Atlantic bluefin are the largest, and also the best divers, reaching depths roughly 3,300 feet deep.īluefin tunas are the most sought-after tuna in sushi restaurants, and for many years the intense fishing pressure caused many bluefin populations to plummet. ( Thunnus orientalis) in the northern Pacific Ocean, and southern ( Thunnus maccoyii), in temperate regions around the globe. ( Thunnus thynnus) lives in the northern Atlantic Ocean, the Pacific ![]() There are three species of bluefin, each living in a different part of the world. They are also slow to grow compared to all other tuna and have long lifespans of up to 20 years. Reaching average sizes of 5 feet long and 130 pounds, and maximums of about 1,500 pounds, they are the largest of all the tuna. All tunas must continually swim to flush oxygen rich water over their gills, a necessity for a fish with such a high metabolism and muscular body.īelow, the true tunas of the Thunnus genus are listed and some of their unique attributes are described.īluefins ( Thunnus maccoyii, Thunnus orientalis, Thunnus thynnus)īluefin tunas are the kings of tuna. This enables them to travel long distances in cold water, like during the 5,000 mile (8,000 km) long trans-Pacific migration many Pacific bluefin tuna make, or make exceptional dives into deep, frigid water like the southern bluefin. ![]() Most fish lose a lot of their body heat as the warm blood circulates through the gills, but these tunas have a special counter circulatory system that can both conserve body heat and allow for quick warming. The bluefins, yellowfin, bigeye and albacore are some of the few warm-blooded (or endothermic) fishes and can retain the heat they produce as they swim. The appetite for some tuna species is so great that some species are endangered due to overfishing, though conservation efforts seem to be helping in recent years. They are sold to consumers in cans, as steaks, and raw at the sushi bar. Seven of these (plus the related skipjack, Katsuwonus) are called the principal market species sought after by canners and anglers and auctioned at high prices at fish markets. However, the eight members of the genus Thunnus are considered the true tunas. There are 15 genera and 51 species in the Scombridae, the broader tuna family, which includes the bonitos, Spanish mackerels, and mackerels. ![]() Large and athletic, with a mouth full of sharp teeth, they are impressive swimmers with large appetites. Tuna are the predators of the fish world. ![]()
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