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Adequate management of stocks is necessary to avoid overfishing
Adequate management of stocks is necessary to avoid overfishing
FAO/21380/T.Dioses

For the two decades following 1950 world marine and inland capture fisheries production increased on average by as much as 6 percent per annum, trebling from 18 million tonnes in 1950 to 56 million tonnes in 1969. During the 1970s and 1980s, the average rate of increase declined to 2 percent per year, falling to almost zero in the 1990s. This levelling off of the total catch follows the general trend of most of the world's fishing areas, which have apparently reached their maximum potential for capture fisheries production, with the majority of stocks being fully exploited.

Marine catch

World marine catch totals continue to flatten off following the general trend of most major fishing areas of the world were fisheries have evolved from a developing to a more mature and in some cases senescent phase. When known and traditional fish stocks and fisheries are taken into account, the total marine catches from most of the main fishing areas in the Atlantic Ocean and some in the Pacific Ocean seem to have reached their maximum potential years ago and, therefore, substantial total catch increases from these areas are unlikely. In contrast, growth in aquaculture production has shown the opposite tendency. Starting from an insignificant total production, inland and marine aquaculture production grew by about 5 percent per year between 1950 and 1969 and by about 8 percent per year during the 1970s and 1980s, and it has further increased to 10 percent per year since 1990.

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.

Figure 1: Summary of state of stocks, as analyzed in a broad FAO sampling
Figure 1: Summary of state of stocks, as analyzed in a broad FAO sampling
FAO/Fishery Industries Division

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.

 
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