Highly migratory and straddling resources have received intense international attention at the UN Conference on Straddling Fish Stocks and Highly Migratory Fish Stocks (New York, 1993-1995) which led to the adoption, at the end of 1995 of a legally binding international instrument for their improved management. Landings of highly migratory species as listed in Annex 1 of the 1982 Convention on the Law of the Sea are shown in Figure 12, and these show an increase in landings from about 700,000 tonnes in 1950 to about 4.5 million tonnes in 1994. Increases have been most rapid since about 1970. In recent years, over half the total landings of highly migratory species has been accounted for by just two species, skipjack and yellowfin tunas. Skipjack is classified as underexploited or moderately exploited in the Atlantic, Indian and Pacific Oceans (FAO 1995b) and so it is likely that catches will increase further in the near future. In contrast, yellowfin is fully exploited in the present fishing areas of the Atlantic and Indian Oceans and in the eastern Pacific, and moderately exploited in the central and western Pacific and, unless new areas or sub-stocks are discovered, it is unlikely that much increased catches can be sustained in the long term. Figure 12 does not include some species which are highly migratory but which are not included in Annex 1 of the 1982 Convention (FAO 1994), landings of which are negligible.
Figure 12. Landings from highly migratory fish resources by species
A first attempt at listing fish resources which straddle the boundary between exclusive economic zones and high seas areas was provided in Table 4 of FAO (1994). Given constraints due to lack of geographical resolution in the landings data and to a lack of information on stock identity in many cases, it was necessary to specify these straddling stocks in terms of species and FAO major fishing areas. Figure 13 shows the landings of these straddling resources by major fishing area since 19505. Overall landings of straddling stocks increased from less than 2 million tonnes in 1950 to nearly 14 million tonnes in 1989, and subsequently declined to about 12 million tonnes. The landings composition by area has changed markedly during the whole period. The Northwest Atlantic dominated straddling stock landings up to the mid-1960s but then markedly decreased in importance as the Atlantic cod stocks declined, whereas the Northwest and Northeast Pacific greatly increased in importance, due almost entirely to large increase in landings of Alaska pollock. Likewise, the decrease in the overall landings since 1989 is mainly due to reduced contribution of this species.
5 These resources are considered straddling for the whole time period concerned (1950-94) for the sake of convenience and historic perspective even though many of them were high sea resources, legally speaking, before the extension of national jurisdictions, mainly after 1970.Figure 13. Landings from straddling stocks by major fishing area