Trends by species
In 1997 FAO published the results of an analysis of the landings of 200 species from particular oceanic areas (species-area combinations referred to as "resources") which account for 77% of world marine production. This analysis offers an important additional perspective to the levelling off of the growth in capture fisheries production. Four examples of the 12 groups used in the analysis are presented, reflecting phases in the development of a fishery, namely: the undeveloped, developing, mature and senescent phases. These phases reflect the evolution of a fishery from stable, as yet undeveloped, to the rapidly rising level of productivity during which landing rates rise and then fall until a point of maximum landings are reached. Finally, in the senescent stage, the rate becomes negative as the level of landings falls.
Results showed that 35% of these 200 major fisheries resources were senescent, that is, showing declining yields. A further 25% were mature (or fully exploited), 40% were still developing and there were none that remained at a low-exploitation level. Thus about 60% of the world's major fisheries resources were found to be either fully exploited or experiencing declining yields. As few countries have effective control over fishing capacity, these resources are in urgent need of management to end overfishing or to restore depleted stocks.
The state of stocks
In addition, FAO holds information on the state of 392 of the 696 stock items recorded in their database, representing a wider set of resource items than mentioned above. A more recent analysis of these 392 items, summarized in Figure 1, shows that 6% of these stocks appear to be underexploited, 20% moderately exploited, 50% fully exploited, 15% overfished, 6% depleted and 2% are recovering.
While some 76% of these stocks are at or greater than a biomass level approximating that needed to harvest at an optimal level, some 73% are in need of management if they are to avoid becoming overfished or, in the case of those already overfished, if they are to be rebuilt. Some fisheries in this position are under effective management, where access to the fisheries has been limited, thus limiting pressure on stocks. But many fully fished resources are not adequately managed and are therefore vulnerable to rapidly moving into decline, becoming overfished or depleted.