This paper reviews the state of fishery resources of tuna and tuna-like species on a global scale, concentrating on those most important commercially, i.e. the so-called principal market tuna species. They can be classified into tropical tunas (skipjack, yellowfin and bigeye) and temperate tunas (albacore and bluefin [Atlantic, Pacific and southern]). For tuna and tuna-like species, the document outlines:
•  taxonomic and other basic biological information;
•  the development and expansion of fisheries;
•  trends of catches;
•  institutional frameworks for regional cooperation in fisheries research, particularly    stock assessment;
•  procedures and input information for stock assessment; and
•  the status of stocks.

It also discusses:
•  potential improvements in knowledge of the status of stocks; and
•  the outlook for this status and catches in the future.

There are still four or five of the 23 stocks of the principal market tunas that are only moderately exploited. These stocks are: i) albacore in the South Atlantic and the South Pacific (two stocks); and ii) skipjack in the Pacific (two stocks) and, possibly, in the Indian Ocean (which also may be about fully exploited).

Most stocks of the principal market tunas are nearly fully exploited (eight to ten of the 23 stocks). These stocks are: i) albacore in the Indian Ocean and the North Pacific (two stocks); ii) bigeye in the Atlantic and the Indian Ocean (two stocks); iii) Pacific bluefin; iv) yellowfin in all the oceans (four stocks), possibly with the exception of the western and central Pacific (also may be overexploited); and v) possibly, skipjack in the Indian Ocean (also may be moderately exploited).

A significant number of stocks are overexploited or depleted (five to six of the 23 stocks). Among these stocks, two are classified as depleted. These are Atlantic bluefin in the western Atlantic and southern bluefin. The stocks classified as overexploited are: i) albacore in the North Atlantic; ii) Atlantic bluefin in the eastern Atlantic and the Mediterranean Sea; iii) bigeye in the Pacific (perhaps two stocks); and, possibly iv) yellowfin in the western and central Pacific (which also may be about fully exploited).

Of the principal market species, the status of three of the 23 stocks is unknown; namely, albacore in the Mediterranean Sea and skipjack in the Atlantic (two stocks).