Environmental Impact of Aquaculture Aquaculture Production World production

Environmental Impact of Aquaculture

Aquaculture Production • World production doubled since 1984 - 20, 900, 00 mt of fish and shellfish in 1995 • U. S. production has grown by 5 -10 % each year over the past decade - 400, 000 mt of fish and shellfish worth $729 million in 1997 • U. S. aquaculture production is expected to continue to increase steadily

Aquaculture wastes • Wastes consist primarily of uneaten fish feed and fecal and other excretory wastes - Source of nutrient pollution oxygen depletion algal blooms fish kills - Source of nutrient pollution toxic algae (Pfiesteria) fish kills, contaminate shellfish and pose a health hazard to humans

Aquaculture wastes (continue) • Fish feces can carry pathogens which can infect humans - Example : Streptococcus bacteria • Wastes can carry chemicals such as antibiotics to control disease and pesticides to control weeds, algae, and parasites - Copper-based algae-killers - Aquaculture chemicals in food harm or kill shellfish harm humans

Biological Pollution • Introduction of unwanted non-native species to natural ecosystems - alter species composition - reduce biodiversity - introduce diseases and parasites

Reducing Nutrient and Chemical Pollution • Use feed designed to protect the environment - low fishmeal content - minimize fish wastes • Raise fish together with mollusks or hydroponic vegetables - make optimum use of water and nutrients - minimize farm wastes

Reducing nutrient……. (continue) • Closed aquaculture systems can treat wastes with mechanical chemical and biological filters • Open aquaculture systems can place their cages and netpens in areas with strong currents or tides - flash waters avoiding waste accumulation

Reducing nutrient……. (continue) • Chemical pollution can be minimized by practicing preventive medicine - stock fish free of pathogens and parasites - minimize stresses on fish - vaccinate fish against disease

Reducing Biological Pollution • Carefully choose the species or strains for farming - use only native species - use strains of non-native species that cannot survive and reproduce outside captivity • Take measures to minimize escapes of cultivated fish into natural waters • Grow reproductively sterile species

Conclusion • Aquaculture facilities constructed without environmental protection in mind can cause serious environmental degradation • A variety of strategies and technologies are now available to make fish farming environmentally sound • The use of these strategies can make aquaculture more acceptable by the wider public and more productive