FAO prepares regular reviews of the state of world fishery resources and the latest one for marine fisheries (FAO 1995b) classifies the main species fished in each major fishing area according to its state of exploitation, where this has been formally assessed. We here consider all marine resources which are classified in that publication as overexploited or depleted in 1992. The aggregate landings by fishing area for all such resources (except tuna) are shown in Figure 7, and it can be seen that these stocks together showed a decline in production from over 14 million tonnes in 1985 to about 10 million tonnes in 1992 and 8 million tonnes in 1994, i.e. a decrease of about 6 million tonnes in 9 years. However, the Southeast Pacific area (shown in Figure 7 as the uppermost plot component) contains only one species, the South American pilchard, which was virtually unexploited prior to 1973. Exclusion of this element shows that the decline actually started twenty years ago, with most of the decrease attributable to the Northeast, Northwest and Southeast Atlantic areas. For these three areas, plots of landings for the individual species or species groups classified as overexploited or depleted in FAO (1995b) are shown in Figures 8-10. The pattern of long term decline is also evident for landings of some tunas which are classified as overexploited including albacore in the Atlantic which has shown a downward trend since the mid-1960s and Southern bluefin tuna which has shown a more recent but steeper decline as catches have been limited by management in response to declining stock size (Figure 11).
Figure 7. Landings by fishing area all resources classified as overexploited or depleted in 1992
Figure 8. Landings from resources in the Northwest Atlantic classified as overexploited or depleted in 1992
Figure 9. Landings from resources in the Northeast Atlantic classified as overexploited or depleted in 1992
Figure 10. Landings from resources in the Southeast Atlantic classified as overexploited or depleted in 1992
Figure 11. Landings from tuna resources classified as overexploited or depleted in 1992
Thus, many of the resources classified as overexploited in 1992 have been showing decreasing yields for the last twenty years. Together, these resources are now producing 6 million tonnes less than they did in 1985 and about the same as they produced in the mid-1960s when fishing effort was undoubtedly much less than it is now. The aggregate decline of 6 million tonnes in Figure 7, however, masks the successive declines in individual resources and compensation by increased exploitation of others. The sum of the difference between the observed historical peak landings in the time series of each area component smoothed by a 5-year running-mean and recent landings amounts to about 9 million tonnes. This observation implies that, if these individual areas could all be restored to their historical maximum levels, a gain of 9 million tonnes of landings could be expected.