IMPACTS ON SOIL AND WATER RESOURCES AND THE SPREAD OF DISEASE
In some areas pumping of groundwater and/or construction or modification of canal systems has resulted in saltwater intrusion into what were previously freshwater areas. Disturbance and release of acid from acid sulphate soils (common in mangrove areas) as a result of pond digging has also had negative impacts on resource productivity, including aquaculture yields. Excessive acidity is likely to reduce disease resistance.
Overall, the rapid and over-concentrated development of aquaculture, and particularly coastal aquaculture, has resulted in declines in soil and water quality, increased disease incidence, and more rapid disease spread. This has directly and negatively impacted fish farmers themselves, in both inland and coastal environments. The knock-on effects of disease outbreaks are substantial for local communities and national economies. Some recent examples of the economic impacts are listed below:
• The total negative economic impact of two shrimp viruses, white spot syndrome virus (WSSV) and yellow head disease (YHD), has averaged about $1 billion (U.S.) annually since 1994 in major shrimp-growing countries, including China, Thailand, India, Indonesia, Bangladesh, Malaysia, Taiwan, Vietnam, and Japan .
• In Asia, WSSV has caused severe economic losses to the shrimp industry; due to the effects of the virus, China reported losses of US$1 billion in 1993, while in 1995, Thailand lost over US$500 million. At the end of January 1999, WSSV was detected in Nicaragua, Guatemala and Honduras. Later, the virus was also reported in Panama, Ecuador and on Colombia’s Pacific coast.
• Marine finfish disease losses in Japan in 1992 were reported at US$114.4 million (Arthur and Ogawa 1996).
• Between 1995-1997, ”red spot disease” of grass carp affected 4000 of 5000 cages in Northern Vietnam, with losses estimated at US$ 500 000.
Financial losses are not restricted to the tropics or to developing countries as the bankruptcies in Scotland due to ISA outbreaks and Norwegian losses due to Hitra disease in farmed salmon testify. Australia benefits from low production levels in relation to coastal area, and low levels of water pollution generally, permit a high standard of aquaculture products, but there have already been significant production losses due to adverse environmental impacts on and from aquaculture .
SOURCES : John Hambreya and Rod Cappellb. 2003. Environmental capacity: its application for the environmental management of aquaculture in tropical developing countries
Overall, the rapid and over-concentrated development of aquaculture, and particularly coastal aquaculture, has resulted in declines in soil and water quality, increased disease incidence, and more rapid disease spread. This has directly and negatively impacted fish farmers themselves, in both inland and coastal environments. The knock-on effects of disease outbreaks are substantial for local communities and national economies. Some recent examples of the economic impacts are listed below:
• The total negative economic impact of two shrimp viruses, white spot syndrome virus (WSSV) and yellow head disease (YHD), has averaged about $1 billion (U.S.) annually since 1994 in major shrimp-growing countries, including China, Thailand, India, Indonesia, Bangladesh, Malaysia, Taiwan, Vietnam, and Japan .
• In Asia, WSSV has caused severe economic losses to the shrimp industry; due to the effects of the virus, China reported losses of US$1 billion in 1993, while in 1995, Thailand lost over US$500 million. At the end of January 1999, WSSV was detected in Nicaragua, Guatemala and Honduras. Later, the virus was also reported in Panama, Ecuador and on Colombia’s Pacific coast.
• Marine finfish disease losses in Japan in 1992 were reported at US$114.4 million (Arthur and Ogawa 1996).
• Between 1995-1997, ”red spot disease” of grass carp affected 4000 of 5000 cages in Northern Vietnam, with losses estimated at US$ 500 000.
Financial losses are not restricted to the tropics or to developing countries as the bankruptcies in Scotland due to ISA outbreaks and Norwegian losses due to Hitra disease in farmed salmon testify. Australia benefits from low production levels in relation to coastal area, and low levels of water pollution generally, permit a high standard of aquaculture products, but there have already been significant production losses due to adverse environmental impacts on and from aquaculture .
SOURCES : John Hambreya and Rod Cappellb. 2003. Environmental capacity: its application for the environmental management of aquaculture in tropical developing countries