"Robotuna?" It's for Real!
Brink of Extinction
Atlantic Bluefin tuna are one of the most highly evolved fish species…and also on the brink of extinction due to overfishing. The Gulf Coast oil spill disaster didn't help matters either. It is the highest valued Atlantic tuna species commercially available. One fish can sell for tens of thousands of dollars. The name tuna, originates from the Greek word meaning "to rush."
The Bluefin is one of the largest, fastest, and most beautifully colored of all fish. Their streamlined bodies are built for speed and endurance. They can travel approximately 43 mph but have been clocked at up to 50 mph in short bursts. Their coloring helps camouflage them from above and below. Their average size is 6 1/2 feet in length and they weigh approximately 550 pounds. However larger specimens are not uncommon.
A Robot Tuna?
They can retract their dorsal and pectoral fins into slots to reduce drag. And some scientists think the series of “finlets” on their tails may even serve to streamline their bodies for increased speed. This fact has led United States Navy scientists to study them in more depth. In fact, plans have been made to build a robotic Bluefin for surveillance purposes.
Bluefin, Thunnus thynnus,population levels have reached record lows. Due to their extensive migratory habits, international cooperation for management and conservation has proven difficult. Proposals for an international ban or significant restrictions on Bluefin fishing have been largely rejected due to fears of an economic crisis in the fishing industry. Studies on why their numbers are dwindling have been inconclusive however suspected causes include changes in water temperature, currents, availability of food and overfishing.
In 2008 the United States harvested about 3% of the global bluefin catch. Over half of that was exported to foreign markets, primarily Japan. The United States also imports bluefin for consumption, predominantly from Malta, Canada, Spain and several other countries. Unfortunately, their meat also happens to be prized by sashimi eaters, and overfishing has driven their numbers to critically low levels.
The fish is dark blue to black near the dorsal surface and silvery near the ventral surface. They live from 15-30 years and are also homeothermic, or "warm-blooded.” Therefore, they are able to keep their body temperatures higher than the surrounding water.
Bluefin are highly migratory and some have crossed the Atlantic in as little as 60 days. They can be found from Newfoundland to the coast of Brazil. They range in the eastern Atlantic as far north as Norway and down to northern West Africa. Bluefin tagged in the Bahamas have been captured in Norway as well as off the coast of Brazil. The largest tuna ever recorded was an Atlantic Bluefin weighing 1,496 pounds.
The Atlantic Bluefin subsists on smaller fish like mackerel, herring, whiting, flying fish, mullet, squid, eels and crustaceans. They also feed on zooplankton and even kelp and tend to group together according to size.
There are two confirmed spawning locations. One is in the Gulf of Mexico in the western Atlantic and the other in the Mediterranean Sea in the eastern Atlantic. However, little is known why bluefin spawn where they do.
Prior to 1970, sport fishing was merely recreational, as giant Bluefin tunas’ had a fairly cheap commercial value at the time. Giant trophy tuna not kept for display or consumption, were sold to cat and dog food producers. When the Japanese specialty market boomed in the early 1970s, giant bluefin tuna suddenly became a big money market. Now many "recreational anglers" also obtain commercial permits, so that virtually all giant bluefin tuna currently caught are sold commercially.
Bluefin tuna have been eaten by humans for hundreds of years. However, in the 1970s, demand and prices for large Bluefins soared, particularly in Japan. Therefore the commercial fishing industry was prompted to find new ways to catch them. As a result, Bluefin numbers, especially, breeding-age fish, have plummeted. International conservation efforts have led initiatives to reduce catch limits. However, illegal fishing continues to be a huge problem.
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