Arid lands cover more than one fifth of the Earth’s surface, and they are found on every continent. These cover approximately 20 percent of the world land mass and according to the World Meteorological Organization (WMO) climate change and desertification are expected to lead to increasing levels of salinization and desertification of agricultural lands. These drylands are characterized by inhospitable temperatures, inaccessible terrain and scarcity of sweet water which make them difficult for living. Despite the grave problems, it is generally recognized that such areas have a great potential for development. According to United Nations Office to Combat Desertification / United Nations Development Programme (UNCCD/ UNDP) they are home to about 50 percent of the world’s livestock; and about 13 percent of the total world population, approximately 313 million, live in arid zones with 92 million alone residing in hyperarid deserts.
Scarcity of freshwater is the most limiting factor making these areas different worlds, which otherwise present greater development options. These areas largely depend on rainfall and/or groundwater for human needs, livestock consumption and sustaining scant agriculture. However, in the recent times scientific advancement and research have enhanced the knowledge which provides a basis for humans to learn and harness seemingly impossible situations and turn them into productive opportunities. Exploitation of desert and arid land brackish or saline groundwater sources not fit for human consumption or agriculture by cultivating organisms that can withstand high content of salt, is one of the options.
Seawater is being used to farm marine fish and plants all over the world. Similarly, the idea of utilizing desert saline or brackish water for fish farming was formulated in 1963-1965 and tested experimentally, showing that it was possible to use this water to rear fish successfully. The high mineral content of these waters, along with high ambient temperatures and solar radiation in fact support high primary productivity, forming a suitable and favourable food-base for the fish. Since then scientists have been working on developing technologies suitable for fish farming in such areas and as of today many countries have developed successful models for fish production on brackish or saline water available underneath deserts and arid lands. These systems, however, need good water management which includes the use of water saving and recycling, and the introduction of modern aquaculture technologies such as recirculation aquaculture systems. These systems usually occupy a relatively small area and are extremely efficient with water usage with fish productions of up to 50 kg/m3 of water as proved by scientists. The use of desert aquaculture technology does not necessarily require significant investments and can be used for commercial, as well as small-scale affordable aquaculture initiatives.
Apart from the farming of table fish, other commercially important and valuable organisms, tolerant to high salt concentrations and high temperatures, can also be produced in arid areas. Small brine shrimp, seaweed and the unicellular green algae are few examples. Currently, Australia farms and supplies over 60 percent of the world’s natural b-carotene extracted from Dunaliella salina which is mainly produced in large ponds of saline water extracted by tubewells in South and Western Australia (Benemann, 2008). Furthermore, innovative fish/vegetable co-culture systems are another option, which use the nutrient by-products of fish culture as direct inputs for vegetable production, constantly recycling the same water in Aquaponics systems.
Fish farming in desert and arid lands is considered a fertile and lucrative enterprise these days. Many countries have developed fish farming in deserts and arid lands thus making them arable and productive. USA, South Africa, Mexico, Qatar, Saudi Arabia, Egypt and Israel are some examples. Israel is one of the leading country which has developed important innovations in the arid and desert aquaculture by using saline ground water. It is exporting fish, vegetables and other agri products produced in these desert systems. These systems are efficient in producing quality fish and vegetables or fruits than in conventional systems. Climatically, except for the northern part most of Pakistan is arid or semi-arid in nature, however by virtue of well-developed irrigation system the effects are neutralized and practically the arid lands are confined to deserts and hilly areas that do not receive irrigated water. These include Cholistan, Thall and Pothwar region in Punjab; Thar, Kachho and Kohistan in Sindh; and Kharan desert and hilly part of Balochistan. Generally, prevalence of poverty is high in these areas and resources are scarce. Development and communication infrastructure is also very poor.
Current situation in arid areas of Pakistan demands taking immediate food security measures, particularly in Thar desert, Kachho and Kohistan in Sindh where life is facing acute food security issues. There is urgent need for utilizing saline or brackish water resources available in these areas to produce marine fish and shrimp along with certain vegetables where possible (in integrated fish-vegetable) aquaponics systems. This will serve the purpose of securing food supply in areas where conventional agriculture is not an option. This new technology could generate jobs, create business opportunities and improve livelihoods in desert and arid land locations through the cultivation of fish.