Introduction
Desert aquaculture has been growing steadily over the last decades and this is due to the modern technologies and alternative energy sources that had given room for water in places of extremes
to be exploited more effectively and efficiently for both crop irrigation and fish production. Deserts cover more than one fifth of the Earth’s land, and they are found on every continent.
Deserts cover around 25 500 000 km2 or approximately 20 percent of the world land mass (Smith et al., 2008). These harsh environments are characterized by high day temperatures and
solar radiations, cold winter nights, scarce precipitations and very low relative humidity (Hochman and Brill, 1994).
Desert aquaculture is simply the cultivation of aquatic organisms in arid or semi-arid environments where freshwater is scarce and temperatures are often extreme. Modern techniques
often used are Recirculatory aquaculture systems (RAS) and Groundwater usage, and sometimes integrated with crop farming to optimize water use. It is an emerging resource-intensive solution
that combines water usage innovation with food production in water-scarce regions encompassing strategic planning, regulations and sustainability mindset.
The importance of aquaculture in supplying fish protein to the growing human population is escalating (FAO Fisheries Department, 2011) particularly in regions where other types of
intensive animal husbandry are expensive or even simply not possible. Arid and semi-arid zones are among such regions where conventional agriculture and intensive livestock practices are
severely hindered by the habitat and climate, and particularly the reduced annual rainfall levels.
The idea of desert fish farming was formulated in 1963–1965 and tested experimentally, showing that it was possible to use desert salt or brackish waters to rear fish successfully (Fishelson and
Loya, 1969). 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 (Pruginin, Fishelson and Koren, 1988).
The constant growth of the human population and the continuous exploitation for land and water resources for food production, as well as other economic activities has undoubtedly increase the
extraction of groundwater in arid regions to meet the growing needs. It appears, therefore, that the expansion of monitoring programs and activities of subsurface water extraction and
utilization particularly from arid regions has become increasingly important and should be carefully addressed as adequate replenishment of groundwater resources may occur over long
periods of time.
The availability of water for farming fish and other commercially valuable aquatic organisms limits the extent to which food production sector can develop in these water-poor territories.
However, it is also quite true that water is not exclusively available from underground sources. Other water bodies do exist including natural ponds and rivers that may either be perennial or
seasonal, as well as man-made water retention dams mainly constructed for irrigation purpose and for livestock, and small lakes from abandoned open mines.
The long exploitation and utilization of arid lands in many parts of the world has brought about the buildup of artificial water reservoirs of different typology and dimensions, many of which
harness a great potential for aquaculture activities. The use of such water bodies is well documented in the Australian review where farming of two salt-tolerant fish species, the
Japanese meagre or mulloway (Argyrosomus japonicus) and the rainbow trout (Oncorynchus mykiss) has been successfully demonstrated. Another example, is the case of Namibia where
farming of the Mozambique tilapia (Oreochromis mossambicus) in floating cages is showing interesting production results from disused mine pits that would otherwise remain unproductive.
Apart from the farming of table fish as the two species mentioned above, other commercially important and valuable organisms, tolerant to high salt concentrations and high temperatures, are
available and attractive candidates for commercial production in arid regions. The small brine shrimp, Artemia sp. and the unicellular green algae, Dunaliella sp. are two examples. Currently, Australia farms and supplies over 60 percent of the world’s natural ß-carotene extracted from Dunaliella salina which is mainly produced in large saline evaporation ponds in
South and Western Australia (Benemann, 2008).
The excessive use of underground, as well as surface water resources in many countries with extensive arid regions have forced many fish farming entrepreneurs and research institutions in
developing water-saving strategies including the harvesting of run-off water, sharing water from reservoirs with green crops and the exploitation of saline water sources not fit for human
consumption or agriculture (Mires, 2007).
At present, in the middle of the Atacama Desert the “Solarium Appropriate Biotechnology Group for Desert Development” has developed a culture and processing system for producing this
filamentous cyanobacteria. Spirulina is cultured in polyvinyl chloride-lined raceway ponds covered with translucent UV-resistant polyethylene film to maintain adequate temperatures in
the culture medium (Habib et al., 2008).
Although climatic conditions in many arid territories makes it virtually impossible to obtain enough water to sustain livelihoods (<250 mm/year), there are many areas rich with underground
water sources, while in some places, these sources are currently being used to supply local populations with daily rations of water for personal use.
Suitable Species for Desert Aquaculture
A large variety of organisms can be cultured in arid conditions, particularly if the technology used is adequate for the proliferation of the farmed species. However, in the selection of species
to be reared in desert and arid environments, a few general criteria are recommended such as;
- The species should be particularly tolerant to hyper-saline waters,
- Have high tolerance to large temperature fluctuations and
- Fast growing species to face off water limited conditions typical of these arid areas.
The choice of the species is obviously also influenced by other factors such as the
- availability of farm inputs,
- market value and volume,
- local consumption and preferences and
- dietary habits.
Currently, the most suitable fish species for water-limited aquaculture systems include the
- Tilapias (Oreochromis spp.),
- Barramundi or the Asian seabass (Lates calcarifer),
- Carps and Mullets (Mugil cephalus and Liza ramada) and
- Catfishes species (Clarias gariepinus and Bagrus spp.)
- Indian white prawn (Penaeus indicus)
- European seabass (Dicentrarchus labrax)
- Gilthead seabream (Sparus aurata)
In the case of tilapias, they can be reared intensively in mono, as well as in polyculture systems with other compatible and commercial species such as carps and mullets. They are a hardy group of fish that can be farmed in a wide range of salinities with relatively short production cycle (6 to 8 months to market size).
In many countries, where indigenous species of tilapia or hybrids, such as the red tilapia (O.mossambicus x O. niloticus), are produced they fetch a good market price and are in high
demand. With regard to shrimp, the Indian white prawn (Penaeus indicus) represents a successful example of marine aquaculture production at large commercial scale (e.g. in Saudi
Arabia). This penaeid species has in fact a wide tolerance to salinity variations and hence, a suitable candidate for aquaculture under such environmental conditions.
In Egypt, among other countries, good results have been achieved with the rearing of the European seabass (Dicentrarchus labrax) and the gilthead seabream (Sparus aurata) in brackish
waters. These marine species, however, require the use of advanced technology and technical
skills which are not always available.
As already mentioned in the previous section, other than suitable finfish and crustaceans, microalgae and the filamentous Spirulina are suitable candidates currently being produced in
several arid coastal regions around the world. However, the production of these latter organisms may necessitate large capital investment and technical skills in order to produce them at costs
that are competitive in the current markets.
Worth mentioning is also the ornamental fish farming subsector which has been gaining importance with an export market value growing at an average annual rate of approximately 14
percent (FAO, 2010).
Advantages of Desert Aquaculture
- Efficient utilization of non-arable desert land
- Promotion of local food production in remote or landlocked regions
- Reduction of dependency on imported foods
- Availability all year-round due to controlled conditions
- Employment and economic diversification in rural areas.
Challenges and Constraints of Desert Aquaculture
- Water sustainability concerns especially where fossil aquifers are tapped (Morrison, 2024)
- High energy cost for water pumping, heating, cooling and filtration
- Environmental regulation gaps in unregulated aquifers (Arizona Water Institute, 2023)
- Risk of salinization and groundwater depletion if water is not properly managed (Sommerville et al., 2014)
Small Scale Aquaculture Practice in Desert & Arid Lands of Ouargla, Algeria
Commercial Aquaculture Farms in Desert & Arid Lands of Ouargla, Algeria
Commercial Aquaculture Farms in the Desert of Sonoro Mexico
References
Arizona Water Institute, (2023). Groundwater Governance in arid U.S regions; A policy overview, Arizona State University Press.
FAO. 2010. The state of world fisheries and aquaculture 2010. Rome. 197 pp. (also available at www.fao.org/docrep/013/i1820e/i1820e.pdf).
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Morrison, T, (2024). Water wars in the West; Aquifers, agriculture and aquaculture. Western Water Journal, 18(2), 34-41
Sommerville, C., Young, R., & Becker, A. (204). Aquaculture in arid lands; Best practices and environmental impacts. Journal of Aquaculture Research & Development, 5(3), 112-119. https://doi.org/10.4172/2155- 9546.1000212.
Author: Abibat Ogunrinde