Physical Alterations and Destruction of Habitats (PADH)
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AquacultureIntroductionAquaculture - the cultivation or farming of fish, shellfish and algae - has been practiced for centuries in many parts of the world. Today, it is the fastest growing animal food- producing sector, and a rapidly expanding and productive industry in the coastal zone. The contribution of aquaculture to the world total supplies of fish, shellfish and molluscs has grown steadily, increasing from just below 4 per cent in 1970 to over 27 per cent in 2000. Since 1984, aquaculture has grown by 300 percent. In 2001, the total production including aquatic plants (excluding production in the People's Republic of China) was 18 million tonnes. Projections indicate an increase of production to between 27 and 39 million tonnes in 2010. Aquaculture has the potential to significantly contribute to the world's aquatic food supply, and thus to food security (without overexploitation of natural marine and coastal resources), and alleviation of poverty. It can support economic growth, community development and coastal livelihood. The aquaculture sector already provides a significant number of full-time or part-time jobs in many parts of the world, particularly in Asia where estimates show that approximately 7 million people were employed in the sector in 2000. However, ill managed aquaculture will cause negative impacts on ecosystems, habitats and species. Threatened or particularly sensitive ecosystems include mangroves, estuaries, sea grass meadows, coral reefs, enclosed and semi-enclosed areas such as archipelago areas and fjords, as well as specific benthic species and/or communities. If at all possible, restoration measures when a facility has been taken into operation are very limited. Such actions are also likely to be very costly. The ecological effects on coastal and marine environments include loss or alteration of habitats, including changes of the natural coastlines and reduction or total destruction of natural habitats. In many places, wild capture fisheries are affected, as spawning and nursery grounds are destroyed. The siting of aquaculture facilities in mangrove areas not only impairs the habitat itself but also reduces coastal protection and other functions of the ecosystem. Negative socio-economic impacts on local inhabitants and communities may include depriving them of their traditional life styles (small-scale fishing, using the products from the mangroves) as a result of mangrove exploitation, exclusion from traditional fishing grounds, destruction of fishing grounds, and water pollution (eutrophication, pollution of antibiotics and antifoulants.) Development of aquaculture leads not only to significant local physical alteration of coastal areas in the immediate vicinity of the actual site but may affect much larger geographical areas. Thus, it is essential that the potential effects beyond the altered area, and the combined, total impacts of series of facilities in a particular area be taken into account before development is approved. The rapid development of the aquaculture sector has given rise to much discussion about both its environmental and socio-economic impacts, These impacts have caused concern about the sustainability of the industry itself, and much effort has also been devoted to identifying and promoting management practices that will facilitate a more sustainable continued growth of the industry. To be sustainable, the aquaculture sector must ensure that its impacts are kept within environmentally acceptable limits.
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