Contents - Previous - Next

Fisheries resources

The 1984 FAO World Fisheries Conference endorsed a Strategy for Fisheries Management and Development and approved five associated Programmes of Action which now serve as an international framework for fishery management and development. The Strategy provides guidelines for the sustainable use of fishery resources and the protection of aquatic habitats from pollution and other forms of environmental degradation, including those originating from fisheries, especially aquaculture. The Conference also adopted a special resolution calling for international action to protect the fishery resources of developing countries from pollution.

Two major issues are of importance when considering sustainable development and environmental conservation with respect to fisheries: first, the characterization and assessment of the present state of living aquatic resources and their environment; and, second, the various technical interventions relevant to the sustainable use of fishery resources and the protection of the aquatic environment.

Increased productivity can help fisheries compete with more destructive uses of coastal lands. At a mariculture research center in India, students conduct feeding experiments on young finfish.

The combination of population growth and efforts to raise living standards has created stress on the financial, physical and human resources of developing countries. It has often exacerbated poverty and triggered migration to coastal areas. This has led to overfishing and, partly through the introduction of inappropriate technology, contributed to the degradation of the environment. Lakes and rivers have also been altered by human activities, nearly always with negative consequences for fisheries. Water quality has become a major concern in aquaculture. Freshwater fisheries are adversely affected by the lowering of lake levels and drainage of wetlands,: and by water extraction, siltation, the construction of dams and the regulation of rivers for navigation and flood prevention.

Coastal ecosystems, such as estuaries' marshes, shallow bays and wetlands, mangroves, coral reefs and seagrass beds, play a major role in the life cycles of many economically important fish species by providing breeding, nursery and feeding grounds: about 95 percent of the world's marine production originates from coastal ecosystems. Their accelerated degradation by land reclamation, drainage, coastal construction and other competing uses now poses a serious threat to marine fisheries.

Fisheries are generally not the culprit but rather the victim of environmental degradation.

The exploitation of natural resources and habitats is a function of human population size and development, and the trends towards accelerating urbanization, more powerful technology, greater affluence and faster transport are expected to continue throughout the world. Fisheries are, in fact, generally not the culprit but rather the victim of environmental degradation. Controlling coastal development and protecting habitats will, however, often involve painful social and political choices.

The magnitude and pace of the anticipated global climate changes are still not clear, and it is therefore difficult to forecast their effects on fisheries and aquaculture. Large changes in total marine fish production are not expected, although particular stocks will be affected. Changes in rainfall patterns and river runoff, as well as sea-level rise, will affect life in coastal nursery areas. Tropical upwelling zones, which produce large amounts of fish, might shift polewards by 200 to 700 kilometres and increase in strength. The year-to-year variability of the resources they support may also increase. However, the increased plankton productivity may reduce oxygen levels and lead to anoxic conditions. Financial consequences are hard to- predict and it is difficult to initiate major interventions until better forecasts are available. Premature, ill-informed decisions could be costly and dangerous, although there is also a risk in taking no action at all.

Chemical pollution, even at low levels, may influence fish production in numerous ways. They include: reduction of stocks by mass mortality; gradual decline or change in species composition, of fish populations or entire ecosystems; increased occurrence of disease; deterioration of the food quality of fish and reduced growth rates. Seas and land-locked water bodies receive a significant proportion of polluting chemicals via the atmosphere so that effects far distant from the source cannot be discounted.

Nutrient-rich wastes boost primary-production in otherwise nutrient-poor seas. They may even enhance fishery resources, although they tend to favour the production of small pelagic fish of low economic value. Such wastes may lead to eutrophication, subsequent oxygen depletion and anoxic conditions in the deeper layers of lakes and stratified seas.

Fish productionhas grown rapidly and has put tremendous pressure on resources. Almost all bottom- dwelling species are already either fully exploited, overfished or depleted.

The uncontrolled cutting of mangroves and the clearing of mangrove swamps for various purposes, including coastal shrimp farming, will destroy the nursery grounds of a number of commercially important marine species and adversely affect those living resources inhabiting the ecosystem. Furthermore, shorelines will be deprived of natural protection from winds and waves, with a consequent increase in coastal erosion.

Fishing modifies the structure, species composition and reproduction rates of both targeted and non-targeted fish stocks. Moderate levels of exploitation remove old, slow-growing individuals and reduce the abundance of large predators, thereby increasing the productivity of the remaining stocks and the sustainable yields. High levels of exploitation reduce large, slow-growing species to 'commercial extinction'. Although few cases of biological extinction by fishing alone have been documented, uncontrolled fishing can have serious ecological consequences, such as the destruction of coral reefs or sea-grass beds.

Environmental capacity and 'acceptable' levels of impact should ideally be established in advance, since any human activity may irreversibly change some components of the marine environment.

About 13 percent of the world catch of aquatic resources comes from inland waters, half of it from fresh-water aquaculture. Most fisheries are small-scale subsistence or commercial operations. They exploit lakes, rivers, reservoirs and flood-plains in competition with other human activities, and nearly all major enclosed water bodies are now seriously affected by these competing uses. As major controls on inland water environments are exercised by non-fishery users, fishery managers must participate to a much greater extent than at present in the planning of the integrated use of river basins.

About 10 percent of global fish production comes from aquaculture: approximately 7 million tons from freshwater aquaculture and 5 million tons from mariculture. At present growth rates, production by the end of the century should have almost doubled. In areas of high production, environmental problems are already apparent and will affect further growth in the sector. (See panel) To avoid this situation, planning should cover areas such as environment, social interests and economic policies (including credits and incentives).


One of the highlights in the recent history of aquaculture is the growth in production of shrimp. In tropical coastal areas, using simple earth ponds, tidal or pumped water supplies, local or hatchery-reared seed, and simple fertilization or feeding, a marketable crop of shrimp can be produced in as little as three or four months. Annual yields range from 200 to 500 kg/ha in simple extensive tidal ponds using natural productivity, to upwards of 10 tonnes/hectare in modern intensive systems with artificial feeding, aeration and regular water exchange. Sold on the international markets shrimp is an almost perfect export: it uses basic local resources to bring in foreign exchange. Recognizing its potential, FAO has played a key role in initiating and supporting the industry with inputs in technical development, training, information services and institutional backstopping.

In production terms, the result has been impressive. In 1981, cultured shrimp accounted for 2.1 percent of the total world shrimp harvest, while in 1988 this share had risen to 22 percent. Output in 1988 reached some 450 000 tonnes, corresponding to a farm-gate market value of perhaps US$2.5 billion. Much of this originates in the developing world, particularly in Southeast Asia and Latin America.

As a result of this development, rural coastal land of limited agricultural potential has acquired ,a new status and value. There are also new prospects for income and employment: traditional brackish water fishpond operators have a new source of income; fishing communities can get involved in catching seed shrimp and broodstock; and farms and hatcheries in rural areas can offer local employment and training for young people. In Southeast Asia, 'backyard' hatcheries have provided excellent opportunities for small family-based businesses whose earnings stimulate their local economies.

However, much of the potential of the industry, not least its current sustainability, is under question. After a decade of increasingly rapid and profitable growth, shrimp farming is facing the consequences of its own unrestrained expansion. Markets are showing increasing signs of saturation, disease losses are occurring as a result of environmental degradation and the widespread clearing of mangrove areas, the erosion of coastal margins, and the salinization of coastal flood plain soils are giving cause for increasing concern.

If shrimp farming is to bring real and continuing benefits to producer countries, means will have to be found to stabilize the industry, increase its efficiency and reduce its adverse impacts. This will require the right kind of market and technical support, planning and regulatory advice, particular care over resource management, and social and environmental assessment. These concerns are already being addressed in current FAO projects in Asia and Latin America, and while support for production continues, the emphasis is shifting more strongly towards ensuring sound, well-structured, sustainable shrimp farming in the future

Sustainable development is particularly relevant to fisheries since it implies increasing the benefits from aquatic resources without decreasing the resource or stock beyond some optimal and sustainable level. The concept of sustainability has always been the basis of fisheries management. It includes the sustainability of the biological resource, its value and the social benefits deriving from it. It also implies an assumption of reversibility. Exploitation will inevitably affect the abundance, spawning biomass and species composition of a fishery resource, and the need to conserve options for future generations implies that such effects should be reversible within some practical time-frame.

In the aquatic environment, sustainability does not mean constancy. Since the seventies, short-term variations in marine resources due to fishing and natural fluctuations have been recognized as important factors in assessment and management. The interaction between fishing and the species making up the resource is also an important factor. Under heavy fishing pressure, species dominance changes towards small, short-lived pelagic species, thereby modifying the resource base and the options available for development.

Conservation of aquatic biodiversity poses problems at two main levels. In wild stocks, the loss of species (and more especially local races) through bad fishing practices, environmental change or species introduction (including escapes of cultured species), is a real and persistent danger. In cultured species, the need to develop new strains and conserve favourable ones is increasing.

Fisheries and aquaculture have, to a certain extent, lagged behind other sectors of agriculture and forestry in the exploitation of genetics and biotechnology for management and development. However, the effects of present fishing and management practices on wild fish stocks, and the advantages of genetic manipulation to aquaculture, are becoming more apparent.

It is FAO's long-term goal to improve the national capacity of individual nations to deal with the complex issues of sustainable development of fisheries and their implications for environmental management. Although very few fishery resources are actually threatened by extinction, immediate action is required to stop the present trends towards degradation of resources and habitats, rehabilitate them and promote the conditions necessary for sustainable development. FAO's priorities are to improve the quality and accessibility of information, to strengthen fisheries institutions and their planning and decision-making mechanisms, and to strengthen the international legal framework of fisheries development. With special reference to marine environmental protection, comprehensive strategies should be developed that will take into account all available options for waste disposal on land and in the sea, and that will avoid the error of considering the marine environment in isolation. With this aim in mind, FAO participates in the Group of Experts on the Scientific Aspects of Marine Pollution (GESAMP) which is jointly sponsored by IMO, FAO, UNESCO, WMO, WHO, IAEA, UN and UNEP.

Contents - Previous - Next