![]() ![]() A study of the stomach contents of New England bluefins by Bradford Chase of the Massachusetts Division of Marine Fisheries revealed that the predominant food item, by weight, was Atlantic herring, followed by sand lance, bluefish and miscellaneous squid. Tuna are metabolically adapted for high-speed chases, but as opportunistic (and by necessity, compulsive) feeders, they will eat whatever presents itself, whether it is fast-swimming mackerel, bottom-dwelling flounder or sedentary sponge. Like wolves, bluefins often hunt in packs, forming a high-speed parabola that concentrates the prey, making it easier for the hunters to close in. “The more sophisticated our robotic-tuna designs become,” the Triantafyllou brothers wrote, “the more admiration we have for the flesh-and-blood model.” The researchers found that the tail’s efficiency lay in the interaction of the vortices created by its rapid flexing, but the hydrodynamics of their electronic models did not even come close to that of a true bluefin. It is such a marvelous swimmer that when scientists in the 1990s endeavored to build a mechanical fish, they used the species as a model, designing a robot with a tapered, bullet-shaped body and a rigid, quarter-moon tail fin. The bluefin is also among the fastest of all fishes, capable of speeds up to 80 kilometers per hour and able to migrate across entire oceans. During a dive to one kilometer below the surface, where the ambient water temperature can be five degrees Celsius (41 degrees Fahrenheit), the bluefin can maintain a body temperature of 27 degrees C (81 degrees F), close to that of a mammal. Whereas most of the approximately 20,000 fish species are cold-blooded, possessing a body temperature the same as that of the water in which they swim, the bluefin is one of the few warm-blooded fishes. Reaching a maximum known weight close to three quarters of a ton and a length of four meters, the bluefin is a massive hunk of superheated muscle that cleaves the water by flicking its scimitar-shaped tail. Heedless overfishing is steadily pushing the bluefin toward extinction, and the species may soon disappear unless entrepreneurial fish farmers can learn how to breed the tuna in captivity. As such, it has vaulted to the top of another, more insidious list: it is probably the most endangered of all large fish species. But the bluefin tuna, a giant among fishes, is the premier choice for sushi and sashimi and has become the most desirable food fish in the world. The canned tuna fish in sandwiches and salads comes from either skipjack, a meter-long species that is caught in prodigious quantities around the world and served as “light meat tuna,” or albacore, another small fish that is marketed as “white meat tuna.” The yellowfin and the bigeye tuna are larger species that are also heavily fished, but neither makes for particularly wonderful sushi, and they are usually served grilled. This fact has generated an alarming situation due to the fact that the biomass index has dropped by 15%, after the uncontrolled and even illegal exploitation of this species.Editor's Note: This story was originally printed in the March 2008 issue of Scientific American.Īll tuna are not alike. So its price in the market is usually very high.Īs a result, this species is classified as an endangered one. All this due to their large size and the large amount of meat they can provide as a food.Īt present the giant tuna, is the protagonist of the world’s main fisheries, since its use is also implemented to prepare sushi dishes in Japan. Even in timĮs of the ancient Greece, they were captured very often. Giant Tuna Fishingįor a long time, the giant tuna has been very appreciated in the market for human consumption. However, they can also be seen in tropical waters such as the Gulf of Mexico. The giant tuna tends to prefer the waters with cold temperatures, the most common cases are the coast of Newfoundland in Iceland. A few time ago, it was also common to find them in the Black Sea and the Caspian Sea but now this species is already extinct in these places. In the same way, it is very common to find this creature in the Mediterranean Sea. In general, it is very common to find giant tuna on the two shores that make up the Atlantic, that is in the western and eastern ends. ![]()
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