Tuna are found all over the world due to their large migratory pattern. Although the bluefin tuna is considered the largest, and therefore the most commercially valuable, there are seven species that fall into the genus, Thunnus. Aside from the bluefin, the other types of tuna are the albacore (T. alalunga), yellowfin tuna (T. albacares), southern bluefin tuna (T. thynnus maccoyii), bigeye tuna (T. obesus), blackfin tuna (T. atlanticus), and longtail tuna (T. tonggol).
WHERE TUNA LIVE
Tuna are a migrating species, and travel over long distances. They are therefore, widely hunted and caught by fishermen throughout the world’s oceans.
Tuna vary in size from a fairly medium size to very large, with the largest being the northern bluefin that can weigh in at around 1,800 pounds, and grow to a length of 14 feet.
Because of the overfishing of this particular tuna, their numbers have declined drastically. Although a moratorium has been suggested, it has yet to be implemented, and the decline in numbers is getting larger each year.
FACTS AND MISCONCEPTIONS
There is a misconception that the large size of this fish prevents it from moving very fast, and thus not able to avoid their predators (anglers aside). In reality, they can swim more than 40 miles per hour by retracting their pectoral and dorsal fins to reduce the drag across their bodies.
Another misconception is that tuna are vegetarians when, in fact, they are omnivores. They eat other sea animals, fish, plankton, kelp, and other types of vegetation.
Tuna are also warm blooded. They can regulate their own body temperature. This is rare among fish, since fish are known to be cold blooded.
They have natural camouflage to aid them in avoiding predators. They are dark blue on the top and silver on their underside to help them blend in with the darkness below the surface of the ocean.
The bluefin tuna can dive to an amazing depth of more than 3000 feet, and has an eyesight that is better than any other bony fish.
The Atlantic bluefin can live up to 35 years old, but rarely do, because of the fishing industry.
TUNA, “THE CHICKEN OF THE SEA”
Tuna is a very popular food due to its nutritional value. So, it is not surprising that tuna, especially albacore and yellowfin tuna wind up in a tin can. It also is a favorite sushi treat, especially in Japan.
Tuna is one of the best sources for vitamin D, omega-3, and protein. The oil from fish is used in producing bottled omega-3 capsules as a daily health supplement.
THE PLIGHT OF THE TUNA
The Atlantic blue fin, the largest of the tuna species begin life as an almost microscopic larvae, weighing only a few grams. By three to five years, they are sexually mature and around three feet long. Whilst they are small, they fall prey to other larger predators. Once they reach maturity, they have few enemies, but commercial fishermen are their greatest threat.
Fishermen take advantage of these fish during spawning time. At spawning, the tuna are massed together to mate and lay eggs. This makes them vulnerable to predators and fishermen alike. Once the eggs are released into the ocean, They hatch within two days, thus giving the offspring a greater chance of maturing faster.
Not only is the fishing industry a major threat to the tuna, but environmental changes are having an alarming negative effect on the tuna population.
With global temperatures rising, a decrease in the supply of oxygen and carbon in the ocean is becoming apparent. The seawater is getting warmer. This can affect the bluefin tuna’s ability to swim, spawn and lay eggs. Researchers have found that the eggs are less likely to survive in the warmer water and prefer cooler water. This change in the ecosystem of the ocean affects many species of fish, which plays a large role in the food chain for the Atlantic bluefin tuna.
Conservation efforts are not enough to prevent the extinction of this highly sought after species. Bluefin numbers have decreased by 90% since the beginning of the 20th century
The tuna is considered an endangered species and their numbers are decreasing at an alarming rate. Greater awareness needs to placed on the tuna as to their plight and the future of the species. Unless there is a drastic decrease in overfishing, the tuna will suffer the fate of many other species. In the next few years, this fish will no longer exist to supply the great demand the world has placed on it.