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1. Introduction

1.1 Definitions and Background

FAO (1990) defined aquaculture as "the farming of aquatic organisms, including fish, molluscs, crustaceans, and aquatic plants. Farming implies some form of intervention in the rearing process to enhance production, such as regular stocking, feeding, protection from predators, etc. Farming also implies individual or corporate ownership of the stock being cultivated. For statistical purposes, aquatic organisms which are harvested by an individual or corporate body which has owned them throughout their rearing period contribute to aquaculture, while aquatic organisms which are exploitable by the public as a common property resource, with or without appropriate licenses, are the harvest of fisheries."

For the purposes of this document, the geographical area covered by the term "coastal" includes the shoreland influenced by the sea, the water column and the seabed extending to edge of the continental shelf (Sorensen and McCreary, 1990). Hence, the term "coastal aquaculture" covers land-based and water-based brackish and marine aquaculture practices.

Aquaculture production is increasing worldwide, and it is expected that aquaculture activities will be expanding significantly in the near future as practices are further improved and diversified. Aquaculture production in 1990 constituted approximately 15.3% of the world's fishery production (see FAO, 1992) as compared to 14% in 1989 (New, 1991; see also FAO, 1991 a). Coastal aquaculture production in 1990 amounted to approximately 7.5 million metric tons estimated to be worth US$ 13 230 million (see FAO, 1992). Driving forces in aquaculture development are the increasing demand for aquaculture produce, generating profit and income, and the urgent need for sustainable food supply.

Aquaculture interacts with the environment. It utilizes resources and causes environmental changes. Most interactions have beneficial effects. There have been substantial socio-economic benefits arising from the expansion of aquaculture. These benefits include increased income, employment, foreign exchange earnings and improved nutrition (Pullin, 1989). It should be recognized that to date the majority of aquaculture practices have had little adverse effect on ecosystems. Nevertheless, some cases of environmental degradation in coastal areas have occurred due to, for example, intensive cage culture operations in Europe and shrimp farming practices in Southeast Asia and Latin America.

Aquaculture operations in many temperate and tropical countries still can be improved. Current aquaculture development efforts need to be strengthened to further improve the management and operation of many aquafarms to ensure their durability and environmental compatibility. Unfortunately, the planning and coordination of aquaculture development supported by an appropriate information base containing sufficient technological and socio-economic data is still an exception rather than common practice in most countries.

Although there is potential for development in many areas, aquaculture may increasingly be subject to a range of environmental, resource and market constraints. Aquaculture is competing for land and water resources, which in some cases resulted in conflicts with other resource users. Also, there is growing concern about the environmental implications of aquaculture development, comprising the adverse effects of aquaculture operations on the environment as well as the consequences of increasing aquatic pollution affecting feasibility and sustainable development of aquaculture.

During the last two decades, increasing attention has been directed toward the potential environmental hazards associated with aquaculture development. In some cases, environmental problems have resulted from conversion of wetland habitats, nutrient and organic waste discharges, introduction of exotic species, chemical usage, as well as from deterioration of water quality and decreasing availability of suitable sites for aquaculture. These problems have been repeatedly addressed at international expert consultations, for example, by the Indo-Pacific Fishery Commission (IPFC), the European Inland Fisheries Advisory Commission (EIFAC), the International Council for the Exploration of the Sea (ICES), the Asian Fisheries Society, the International Center for Living Aquatic Resources Management (ICLARM), the World aquaculture Society (WAS), the European aquaculture Society (EAS) and the IMO/FAO/Unesco/WMO/WHO/IAEA/UN/UNEP1 Joint Group of Experts on the Scientific Aspects of Marine Pollution (GESAMP).

1 IMO: International Maritime Organization; FAO: Food and Agriculture Organization of the United Nations; Unesco: United Nations Educational, Scientific and Cultural Organization; WMO: World Meteorological Organization; WHO: World Health Organization; IAEA: International Atomic Energy Agency; UN: United Nations; UNEP: United Nations Environment Programme.

Recommendations from these consultations repeatedly emphasized the urgent need for improvements in various fields including (i) application of appropriate aquaculture methods, (ii) sectoral development planning and management, (iii) integration of aquaculture in multi-sectoral coastal area and river basin management frameworks, (iv) legislation governing aquaculture, and (v) assessment and monitoring of ecological and socio-economic changes associated with aquaculture developments.

1.2 Purpose and Scope of this Document

This document is intended to assist in the promotion of environmental management of coastal aquaculture. It is addressed to all those who are involved and interested in the planning, development and management of environmentally-acceptable coastal aquaculture. It is also intended to serve experts pursuing environmental management and development in coastal areas.

General guidelines are given for environmental management of coastal aquaculture development based on an overview of relevant published information currently available. These guidelines, as formulated in Section 2, directly refer the reader to the relevant sections of the overview containing more specific background and guidance information (Sections 3-6). It is hoped, that, by providing relevant reference material to the guidelines presented, this document proves useful in improving formulation and implementation of appropriate country-specific approaches and actions to meet the particular ecological and socio-economic circumstances governing coastal aquaculture development.

In Section 3 it has been attempted to outline the environmental implications of coastal aquaculture development in the wider context of the utilization of coastal resources and related concomitant environmental changes. Further, main bio-physical and socio-economic factors and causes for environmental deterioration and mismanagement specific to coastal aquaculture are addressed in order to highlight possible constraints to environment-compatible development (Section 4). Methodologies are presented for the assessment and monitoring of environmental hazards and impacts of coastal aquaculture (Section 5). Selected environmental management options are described for possible application both at policy-level and farm-level (Section 6).

Much effort has been made to focus on environmental and developmental circumstances and requirements of coastal aquaculture practices in developing countries. Unfortunately, there is a substantial lack of adequate information and data related to adverse environmental effects of coastal aquaculture in developing countries. Furthermore, information available from temperate countries in most cases cannot be used to qualitatively assess or predict adverse environmental effects of aquacultural practices in tropical environments. Also, much of the concerns so far formulated on the potential adverse effects of aquaculture are still of a speculative nature, and are not borne out by scientific evidence (Pillay, 1992). The paucity of adequate research specific to the different aquaculture practices and their distinct environmental settings makes definitive judgements extremely difficult.

All guideline documentations carry limitations due to both their general character and broad scope. In view of the variety of coastal aquaculture practices and the diversity of their environmental settings found worldwide, it is likely that some of the issues addressed in this document would have needed more detailed elaboration to meet the specific and possibly differing information requirements various readers might have. The readers are therefore encouraged to comment on this document and to make suggestions for its improvement possibly by indicating the specific environmental and developmental circumstances facilitating or restricting progress in coastal aquaculture in their countries or projects.

Environmental management of coastal aquaculture development, and its promotion is a challenging task. Coastal aquaculture is very diverse in terms of the people involved, the resources used, the various methods applied, and, regarding the environmental characteristics of existing and potential sites. Thus, there are opportunities for improved adaptation and integration of aquaculture practices into coastal area development processes. It is believed that appropriate environmental management of aquaculture in coastal areas can be achieved by strengthening efforts towards increased success and efficiency in the development and management of aquaculture operations.

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