Experience Gained in Developed Countries
The Brundtland Report gave these encouraging words on aquaculture development: Aquaculture can be undertaken in paddy fields, abandoned mining excavations, small ponds and many other areas with water, as well as on various commercial scales: individual, family, cooperative or corporate. The expansion of aquaculture should be given high priority in developing and developed countries. This is correct, but such aquaculture development must be socially equitable, environmentally compatible, and have sufficient diversity and scope for change to adapt to changing circumstances.
In the pursuit of environmentally compatible aquaculture development for developing countries, experience gained in developed countries is useful. However, this must be applied with a realistic appreciation of developing-country needs and constraints. Environmental conservation and human needs must be balanced. Where pristine habitats are disappearing there should be all possible efforts to conserve their remnants but developingcountries need realistic policies and legislation to suit their circumstances. The contrast between Philippine coastal waters and Scandinavian fiords is an example. The former support the needs of millions of people, have virtually no pristine habitats andhave suffered massive loss of, and damage to, coral reef and mangrove ecosystems. The latter include many pristine and near-pristine habitats and support very low human populations. Clearly, achievable environmental targets are different for these two contrasting locations.
In examining the environmental impact of, and in setting limits to, the density and siting of cages based on the carrying capacity oflakes, it is essential to balance benefits against any additional pollutingeffect ofthe cages and to consider exactly what environmental and social targets are achievable. Costa-Pierce (1990) made the general point that the environmental impact of cage culture in the Saguling Reservoir was insignificant compared to the impacts of raw sewage and of water level fluctuations, which confound attempts to estimate absorptive capacity.
Criteria for Assessing Environmental Impact and Benefits
Sets of summary criteria, impacts and benefits have been published for appraising developing-country aquaculture development (mcallister 1988; Pullinl989; Tables 5 and 6). Table 5 highlights social and environmental criteria and touches oninternational equity issues. Its message is that the route to the greatest good for the greatest number is fraught with. Complex issues and side effects. The table merely notes these and makes no explicit judgments. Table 6 takes a more structured approach to the social and environmental pros and cons of different types of aquaculture. Here the judgments are more explicit and clearly favor the development of semi-intensive systems. Both tables identi,fy only the broad categories of impacts and benefits. More detailed frameworks are required for specific situations.
Developing-country aquaculture development is needed to help alleviate poverty and increase protein food supply. Poverty and effective environmental conservation cannot coexist. Pauly et al. (1989) illustrate this well for the issue of prevention of dynamite fishing. Development must complement environmental conservation, not compete with it. Therefore, developing-country aquaculture development must be pursued in harmony with realistic environmental conservation objectives, with transnational cooperation and with effective legislation. This will require much more reliable information on the environmental impact of developing-country aquaculture than is available at present. This in turn will require much more research on existing and evolving developing-country aquaculture systems, not just extrapolations from developed-country experience.
Finally, because aquaculture is a relatively new and underdeveloped sector in most developing countries, it will come under increasingly close scrutiny with respect to its environmental impact, perhaps even unfairly so in comparison with the safeguards demanded for betterknown sectors, especially agriculture. This can lead to incomplete and unbalanced commentaries. For example, several agricultural serials publicized the paper by Scholtissek and Naylor (1988) on the possibility of new flu viruses from pigduck-fish zoonoses in Chinese integrated farming but omitted to summarize the rejoinders to this paper published by aquaculturists (for example, Edwards et al. 1988b1, who pointed out the improbability of this in most integrated farming systems.
For these and other similar warnings against the possible environmental hazards of aquaculture development, what is needed is a balanced view – not underestimating the environmental concerns associated with developingcountry aquaculture development but placing these in a broad rural development context in which human needs and all development options and environmental issues receive full consideration.