Abstracts: The Aquaculture Paradox
AAAS Session: Science and the Biosphere,
Aquaculture and Biodiversity
Impacts of aquaculture on biodiversity arise from the consumption of resources, such as land (or space), water, seed and feed, their transformation into products valued by society, and the subsequent release into the environment of wastes from uneaten food, faecal and urinary products, chemotherapeutants, as well as microorganisms, parasites and feral animals. Impacts may extend far from the actual area of cultivation and occur at the local, regional or global levels. Negative effects may be direct, through release of eutrophicating substances, toxic chemicals, the transfer of diseases and parasites to wild stock, and the introduction of exotic and genetic material into the environment, or indirect through loss of habitat and niche space, and changes in food webs. Today, large quantities of fish are caught to produce fishmeal - the main ingredient in feed, which may result in over-fishing and affect marine food-chains, including marine mammals and top carnivores. In some types of aquaculture, fish and shrimp larvae are caught in the wild to be used as seed. This may result in by-catches of high amounts of other larvae, representing losses to capture fisheries and biodiversity. Large areas of critical habitats like wetlands and mangroves have been lost due to aquaculture siting and pollution, resulting in lowered biodiversity and recruitment to capture fisheries. The appropriation of natural resources and ecosystems by aquaculture, "the ecological footprint", increases with scale and intensity of farming, but is very much dependent on which species is cultured and the method of cultivation. The footprint ranges from negligible in cultivation of vegetarian mussels and fish to as much as 50 000 times larger than the actual farm area in intensive cultivation of salmon and other carnivorous fish species.
Socioeconomic Impacts of Shrimp Aquaculture
One of the phenomenal aquaculture stories of modern times, shrimp farming produces more than 800,000 metric tons yearly from some 1.2 million hectares of ponds worldwide. With a total value of US$6 billion, the industry is said to generate a number of benefits, among them export earnings for cash-strapped developing countries, employment opportunities, food production, and poverty alleviation. But "boom-and-bust" shrimp farming has been associated with a number of negative impacts, both environmental and socioeconomic. Ironically, some of the key social issues linked to the unregulated expansion of the industry&endash;increasing poverty and landlessness, decline in food security, marginalization of rural poor, and breakdown of traditional livelihood systems--are the exact opposite of intended benefits. Mangrove goods (from fisheries and forestry) and services (coastal protection, erosion control, flood regulation, nutrient recycling, nursery habitats) are lost with conversion to ponds. Hatcheries and farm complexes have blocked access to beaches for landing boats and drying nets, and reduced lands for pasture and fuel gathering. Agricultural areas especially rice paddies, residential sites, and even burial grounds have been transformed into aquaculture farms. Seepage of saline water from ponds located kilometers inland has caused salinization of soil and water, affecting yields of rice and other crops. Social disruption has led at times to violent conflicts. These problems reflect the process by which rural economies are incorporated into national and international market economies, and are not peculiar to shrimp farming. Nevertheless, these costs to society and the national economy (considered "external" to the production process) need to be internalized by economic and social cost-benefit analyses. The sustainability of shrimp farming requires not only economic profitability and environmental accountability but also social acceptability. Shrimp aquaculture needs to be rationalized within an Integrated Coastal Zone Management which involves the participation of fishers, farmers, local communities and other stakeholders in the coastal zone.
Shrimp Aquaculture And the Environment: Lessons Learned about Best and Worst Practices
Jason W. Clay
During the past 30 years, exports from shrimp aquaculture have come to represent half of the internationally traded shrimp. As might be expected of any new, rapidly expanding industry, commercial shrimp aquaculture's use of natural resources has had tremendous environmental and social impacts throughout the world. These impacts have included the destruction of mangroves and wetlands, the large-scale capture of wild larvae and broodstock, use of fresh and brackish water, production of effluents and other pollutants, use of chemicals and medications, use of fishmeal, and the privatization of public resources. This paper reports the findings of a three-year study co-directed by the author and undertaken jointly by WWF, World Bank, UN Food and Agriculture Organization, and Network of Aquaculture Centres in Asia Pacific. Based on more than 80 case studies completed or in progress, the paper identifies the best and worst practices as well as the incentives and disincentives for their adoption. It also assesses whether shrimp aquaculture can make a net contribution to world fish supplies.
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