Northern bluefin tuna

From Encyclopedia Jr, free information reference for Kids

Northern bluefin tuna
Conservation status
Data deficient (DD)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Perciformes Family: Scombridae Genus: Thunnus Species: T. thynnus
Binomial name
Thunnus thynnus Linnaeus, 1758

The northern bluefin tuna (Thunnus thynnus) is a species of tuna fish, living in both the Western and the Eastern Atlantic Ocean and extending into the Mediterranean Sea and the Black Sea. Although not native to the Pacific Ocean, it is cultivated off Japan. Northern bluefin tuna can live to be up to 30 years old. The typical size is 2 m (6.6 ft) at about 500 kg (1,100 lb). The largest recorded specimen was caught off Nova Scotia, and was recorded as weighing 679 kg (1,500 lb). They are caught by sports fishermen using a heavy-duty rod and reel. The northern bluefin tuna is an important food fish. It should be noted it is used almost exclusively in sushi. Canned tuna and tuna sold as steaks are a different species.

The species is also known as horse mackerel and in the past was called the common tunny. It is often referred to simply as the "bluefin" or "bluefin tuna", but this name is ambiguous as it is also sometimes used for the southern bluefin tuna, Thunnus maccoyii, and the Pacific bluefin tuna, T. orientalis. However, even the preferred name, northern bluefin tuna, is not unambiguous, because this is sometimes used for the longtail tuna T. tonggol.

The body of the northern bluefin tuna is cigar-shaped and robust. The head is conical and the mouth rather large. The color is dark blue above and gray below. Northern bluefin tuna can easily be distinguished from other members of the tuna family by the relatively short length of their pectoral fins. Their livers have a unique and definitive characteristic in that they are covered with blood vessels (striated). In other tunas with short pectoral fins, such vessels are either not present or present in small numbers along the edges.

The northern bluefin tuna is an important source of seafood, providing most of the tuna used in sushi. It is a particular delicacy in Japan where the price of a single giant tuna can exceed $100,000 on the Tsukiji fish market in Tokyo[1]. It is also popular in Taiwan, particularly in the town of Donggang. As a result, some fisheries of bluefin are considered overfished, and this problem is compounded by the bluefin's slow growth rate and late maturity. For these reasons, the bluefin species are listed as "Avoid" on the Monterey Bay Aquarium's Seafood Watch program.

[edit] References

• Clover, Charles. 2004. The End of the Line: How overfishing is changing the world and what we eat. Ebury Press, London. ISBN 0-09-189780-7
• Safina (1996). Thunnus thynnus. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006.
• "Thunnus thynnus". FishBase. Ed. Ranier Froese and Daniel Pauly. January 2006 version. N.p.: FishBase, 2006.

[edit] External links

• Bluefin Tuna at Seafood Watch