Fisheries and aquaculture contribute significantly to food and nutrition security. About 20 percent per capita intake of animal protein for more than 2.8 billion people is from fish and for over 400 million people fish meets 50% of the requirement for animal protein and minerals. Malnutrition is still the number one killer compared to other diseases and fish with its affordable protein and essential nutrients scores over other forms of animal protein. It is a rich source of micronutrients, minerals, essential fatty acids and proteins and is particularly important for the pregnant mother and in child health and development. An estimated 42 million people, majority of them from developing countries work full or part time as fishers and fish farmers. The potential for further improving livelihoods is huge, since it is the fastest growing food sector with 7% annual growth and with 37% by volume of world production traded internationally. For developing countries in relation to the combined earnings from the major agricultural commodities of rice, coffee, bananas, rubber, sugar and tea, the net earnings from fishery products are greater. Production from capture fisheries is not expected to increase much further, as most stocks have reached or exceeded their harvestable limits. On the other hand, aquaculture is growing more rapidly than all other animal food producing sectors, with an average global growth rate of 8.8 percent year since 1970. Of the total global aquaculture production of 68.3 million tonnes (valued at US $ 106 billion), in 2008 from 340 plant and animal species, 93% was from developing countries and this underscores its importance in increasing the income of poor farmers. The importance of aquaculture in meeting the protein requirements from fish is evident from the fact that while kg per capita fish consumption rose from 14.9 in 1995 to 17.1 in 2008, the percentage contribution of aquaculture increased from 29 to 46% for the same period. If the current growth can be sustained, it is estimated to meet more than 50 percent of the total fish requirements by 2015. However the growth in aquaculture can be derailed by climate change unless measures to mitigate and adapt are put in place. Investments in aquaculture compared to other animal protein sources would bring better returns with regard to climate change in view of its considerable limited greenhouses gas and wastes produced per kg of meat.
Climate change is likely to increase the frequency and intensity of climate processes, such as El Niño-Southern Oscillation and there are indications that all surface waters of oceans with some geographical variations are warming and increasing in salinity. Global sea level which has been rising due to climate change has accelerated after 1993. Many lakes especially those in Africa have shown moderate to strong warming since the 1960s. The likelihood of wetlands completely drying out more completely in dry seasons due changes in temperature and precipitation is increasing. The timing, duration and areas flooded are also expected to change. All these are expected to increase the frequency and intensity of extreme floods and droughts. These would increase the risk of livelihood loss and personal security. For example, the thriving catfish farming in Mekong which provides 150,000 livelihoods with a production of 1 million tonnes valued at 1 billion dollars per year would be jeopardised by saline intrusion due sea level rise. African countries which depend greatly on fish for protein and have the least capacity to adapt to climate change like Angola, Congo, Mauritania, Mali, Niger, Senegal and Sierra Leone are semi-arid with significant coastal or inland fisheries - it means higher vulnerability to future increases in temperature and linked changes in rainfall, hydrology and coastal currents. Island nations and others like Bangladesh would be greatly hit by the increase in frequency and intensity of storm and resulting flooding. Since all farmed fishes are poikilothermic, climate changes will significantly alter metabolism resulting in reduced, growth rate, total production, reproduction seasonality and increase vulnerability to diseases. Hence increase in temperature due to climate change will have a much stronger impact on aquaculture productivity and yields.
Aquaculture provides opportunities to adopt to climate change by integrating aquaculture and agriculture, which can help farmers cope with drought while increasing livelihood options and household nutrition. Water from aquaculture ponds can help sustain crops during periods of drought while at the same time the nutrient rich waters can increase productivity. Farmers can use saline areas no longer suitable for crops that are expected to increase due to sea level rise to cultivate fish. Taking advantage of the short generation time and high fecundity, it would be possible to selectively breed fishes to tolerate higher temperature, salinity and increased diseases that are likely to impact aquaculture due to climate change. Aquaculture depends heavily on capture fisheries for fish meal and in certain areas for seed and hence there is an urgent need to find plant protein based alternatives to fish meal and to domesticate species for which there is still a dependence on wild broodstocks. The adaptive response of different communities to Asian tsunami needs to be evaluated to derive valuable lessons for future such extreme events that are likely to increase. To meet climate change there is a greater emphasis on renewable energy like offshore wind, wave and tidal energy and greater nuclear power capacity being proposed with coastal or inland water cooling and these can adversely affect coastal and inland aquaculture unless strategies to mitigate their effect are inbuilt. Finally it is necessary to increase the awareness on the potential to develop adaptive livelihoods, improve the governance and build institutions that can help people, integrate aquaculture in the overall climate change and rural development policies.
To adapt to sea level rise, we should promote agri-aqua farms. Seawater can be converted into potable water through mariculture cum agro-forestry involving mangroves Salicornia, Atriplex, Sesuvium and Casuarina. Coastal aquaculture will then become an important component of sea water farming, thereby opening up new windows of opportunity for using sea water as an important ingredient of sustainable food and nutrition security system.
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