Bluefin Tuna Northern

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 used almost exclusively in sushi; canned tuna and tuna sold as steaks are of other 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. 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.

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Southern Bluefin Tuna

The southern bluefin tuna, Thunnus maccoyii, is a tuna of the family Scombridae found in open southern hemisphere waters of all the worlds oceans mainly between 30°S and 50°S, to nearly 60°S. At up to 2.5 m and weighing up to 400 kg it is one of the largest bony fishes.

The southern bluefin tuna is a large streamlined fast swimming fish with a long slender caudal peduncle and relatively

short dorsal, pectoral and anal fins. The body is completely covered in small scales.

The body colour is blue-black on the back and silver-white on the flanks and belly, with bright yellow caudal keels in adult specimens. The first dorsal fin colour is grey with a yellow tinge, the second dorsal is red-brown, and the finlets are yellow with a darker border.

The southern bluefin tuna is an opportunistic feeder, preying on a wide variety of fishes, crustaceans, cephalopods, salps, and other marine animals.

Catch and management
The southern bluefin tuna is classified as Critically Endangered on the IUCN Red List of Threatened Species.

In 1994 the then existing voluntary management arrangement between Australia, Japan and New Zealand was formalised when the Convention for the Conservation of Southern Bluefin Tuna came into force. The Convention created the Commission for the Conservation of Southern Bluefin Tuna (CCSBT). Its objective is to ensure, through appropriate management, the conservation and optimum utilisation of the global southern bluefin tuna fishery. Later, South Korea, Taiwan and the Philippines have joined, or are cooperating with, the Commission. The CCSBT is headquartered in Canberra, Australia.

At the annual meeting of the Commission in October 2006, which also included representatives from the European Union, it was agreed to cut the global catch by more than 20%, with Japan halving its quota. Prior to this meeting, Japan was accused by Australia of overfishing it's quota by 2-3 times every year during the last 20 years. Japan disputes this figure, but acknowledges that some overfishing has occurred in the past.

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