Shrimp and salmon farming: the impacts on local economies
The alarming increase of world population, expected to be 7.5 billion by 2017, has imposed a pressure on food production and security. A grave concern in this line is the adequate feeding to each individual both in the developed and developing countries. Oceans had been an excellent source of fish food, fulfilling the needs of millions of communities until the fish stocks declined at steady rate. In order to maintain a continuous supply of sea foods, between 1987 and 1997, a rapid growth of farming fish or aquaculture was implemented which grabbed a significant portion in the world fish supplies (FAO, 1999). Although aquaculture is meeting the fish protein need of more than half of the world population, however, environmental and ecological issues are often debatable. Aquaculture of these species undoubtedly enhanced the living status of local communities with job opportunities but some of the inevitable issues include habitat destruction, disease transmission, eutrophication and decrease of wild species which makes the industry economically unreliable for local communities in long run.
Economical impact of shrimp farming
Although shrimp aquaculture is a profitable approach, but intensive farming is the ugly side of such industries. One of the most devastating effects of intensive shrimp farming is the destruction of mangrove ecosystem, which is usually selected for pond facilities however at the cost of destruction of mangrove ecosystem services including nursery habitat, coastal protection, flood control, sediment trapping and water treatment. In Southeast Asia, from the late 1970s 2.5 million to 3.75 million acres various types of wetlands and mangrove forests were brought down for shrimp farming. The lives of local communities relying on the water and fishing in the mangrove ecosystem were also affected vividly. Setting a pond facility for aquaculture involves introduction of sea water which increases salinity of the soil. There are reports wherein the nearby rice farms yield is reduced due to soil salination. In Mekong Delta of Vietnam where most of the aquaculture is done, introduction of saline water impeded the supply of fresh water for agriculture to about 30,000 hectares which eventually drastically limited the rice production (Tran, 1994). Additionally, disease outbreaks in aquaculture farming followed by intense use of chemicals and antibiotics as a treatment measure makes the soil unfit for agriculture and cannot be reverted back due to high salinity and the land is marked abandoned (World Bank et al., 2002). Disease outbreaks also leads to high economical loss to the industry and it may make the local people jobless who might otherwise had a peaceful life by fishing and agriculture.
Economical impact of salmon farming
It is clear that farmed salmons are a threat to commercial salmon fishing. Salmon farming is another harmful aquaculture practices. Farmed salmon are maintained in open net-cages placed in the ocean resulting in the contamination of ocean due to waste excretion, chemicals, as well as disease outbreaks killing the wild species. Salmon being carnivore requires a large portion of wild fishes for food and this in turn depleting the wild fish stocks. Another detrimental effect of salmon farming is the transmission of sea lice, which easily proliferates in salmon farms, to juvenile wild salmon. About 80% of mortality was evidenced among wild juvenile pink salmon (Oncorhynchus gorbuscha) in the pacific coast of Canada as a result of transmission of sea louse from farmed salmon (Krkosek et al., 2007). Besides, literature cites that at times farmed salmon escape from sea cages to open ocean environment where they interbreed with the wild species delivering offspring with reduced genetic diversity, short life span and highly susceptible to diseases (Gardnerand and Peterson, 2003; Thorstad et al, 2008). Because of all the above factors, wild salmon number is decreased and which directly affects the economy of local communities.
Despite of this negative impact on economy, a positive ray is noticed considering the job opportunities brought in by the aquaculture industry. The local people were employed by giving necessary training for sustainable organic farming and thereby meet their manpower requirements. The people were benefitted with the source of living. About 350 people were provided jobs under the Deep Sea Project in Galway Bay. More than 1000 people were provided jobs in aquaculture industry of Ireland. However, reliability of such jobs is questionable owing to sudden outbreaks of diseases in farmed salmon.
There are indeed a few positive aspects of shrimp and salmon aquaculture which includes availability of income to local communities in the coastal region and reduction of wild stock fishing. However, intensive farming adopted to meet the ever increasing demands has devastating effect including disease outbreaks due to overpopulated farming which may affect the wild species leading to loss of genetic diversity. Loss of drinking water to local communities due to mangrove destruction as well as destroying the portable water source seriously affects the economies of local communities. Adaptation of sustainable aquaculture practise and resource management will be a robust solution to reduce such issues.