The suborder Scombroidei is usually referred to as tuna and tuna-like species (Klawe, 1977; Collette and Nauen, 1983; Nakamura, 1985). It is composed of tunas (sometimes referred to as true tunas), billfishes and other tuna-like species. It includes some of the largest and fastest fishes in the sea. The tunas (Thunnini) include the most economically important species referred to as the principal market tunas because of their global economic importance and the intensive international trade for canning and sashimi. In fact, the anatomy of some tuna species seems to have been purposely designed for loining and canning. Tunas are classified into four genera (Thunnus, Euthynnus, Katsuwonus and Auxis) with 15 species all together.

The principal market tunas from the genus Thunnus are albacore (T. alalunga), bigeye tuna (T. obesus), Atlantic bluefin tuna (T. thynnus), Pacific bluefin tuna (T. orientalis), Southern bluefin tuna (T. maccoyii) and yellowfin tuna (T. albacares). Skipjack tuna (Katsuwonus pelamis) is the seventh principal market tuna species.

As is evident from the geographic distribution of their catches (Figure 1), the principal market tunas are all oceanic, capable of long migrations or movements and constituting one or two stocks in each ocean. The exceptions are Atlantic and Pacific bluefins, which occur only in their eponymous oceans. Southern bluefin constitute a single stock extending in the Atlantic, Indian and Pacific Oceans.

+ Read More