Raising fish in the desert? Not such an aberration, according to experts

Raising fish in the desert? Not such an aberration, according to experts

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Tue, 13/11/2012 - 16:05

 

In the arid sands of the desert around Wadi Natroun, 90 kilometers northwest of Cairo, gilthead sea breams swim in fish ponds lined in neat rows.

The salty water found in Wadi Natroun's underground reserves is particularly well-suited to raise marine species such as gilthead sea bream and European sea bass. The brackish water is then used to irrigate special plants tolerant of salt.

"It's all about getting more for your one drop of water," said Aquaculture Consulting Office's Sherif Sadek, a consultant for Wadi Farms' fish farm project in Wadi Natroun which raises sea bream and sea bass.

Integrated desert agriculture is growing in Egypt. Desert farmers realized that the warm freshwater pumped up from underground aquifers to water plants could first be used to raise tilapia and then hearty catfish before becoming irrigation water for nearby crops.

"It takes 8,000 cubic meters of water to produce corn in the desert," said Sadek, adding, "It won't take any more water to first use it to produce tilapia, then catfish and then take the effluent water as irrigation for corn crops. The corn is fed to sheep and goats, whose excrement is used to fertilize the land to produce better corn."

While fish raised in the desert may seem like an aberration, experts believe desert aquaculture could significantly increase the amount of fish on the Egyptian market.

“If we succeed in making desert fish farming a trend, Egypt will increase its fish culture several times over,” says Mohamed Sayed Marzouk, professor of aquaculture and fish diseases at the Cairo University faculty of veterinary medicine.

According to a 2011 FAO report on desert aquaculture, Egypt has 100 intensive tilapia rural farms and 20 commercial aquaculture farms in the desert. These projects account for just 3 percent of the overall aquaculture production of Egypt, according to Sadek.

Most of Egypt's traditional fish farms lay in the Nile Delta region, which has some of the highest population densities in the world. According to the FAO, 1,493 people are packed into each square kilometer, almost twice the average population density rate for the country. As the area continues to urbanize, farmland is shrinking. With so many people, there is little opportunity to expand aquaculture operations.

“There is no potential for horizontal expansion [of aquaculture] in old lands,” said Gamal al-Naggar, the Egypt representative for the World Fish Center.

The desert offers something the cramped, populous Nile Delta region cannot: enough land to expand as operations grow.

“Mainly people will have to move to desert new lands, where there is not much competition on land resources; it's mostly desert and most water is underground,” said Naggar.

In the past decade, an increasing number of farmers are trying their luck in the desert. Already Egyptian farmers have found some success using underground wells and the sandy, desert lands to grow citrus trees, olive groves and for-export luxury crops like strawberries. Adding a concrete fish pond to the operations, experts say, enriches the water in the form of organic waste produced by the fish while costing virtually nothing in water usage.

"You don't have surface water to rely on in the desert," said Marzouk, "The advantage of underground water is that it's almost free from micro-organisms; it's more or less the same as the mineral water we drink.”

Desert aquaculture relies on intensive tank culture. In these deeper, more compact tanks the stocking densities are higher, and paddle wheels or air-injectors are needed to ensure there is enough dissolved oxygen in the water. Constructing the tanks is costly, between LE250,000 and LE300,000, as well as a sizable investment needed for equipment.

While more expensive to set up and maintain, the yields are significantly higher, producing 10 times the amount of fish per cubic meter of water than semi-intensive fish farms, which make up the bulk of Egypt's farming systems.

Fish are fed precisely calibrated pellets that include lipids, vitamins, minerals and digestible proteins in desert aquaculture, according to Marzouk. In traditional and desert fish farms alike, the pellets include testosterone in the first month to ensure that the fry, which is born sexually undifferentiated, develops as a male.

The timing is important, stresses Marzouk: if you expose the fish to the testosterone for too long, traces of the hormone could be retained in the adult fish's tissue and passed onto the consumer. Intensive aquaculture requires tight management of feed quantity, water temperature and barometric pressure.

“If you have good requirements for maintaining the intensive fish culture, it's very good, but if there's problems with water temperature, the dissolved oxygen in water or the ammonia and nitrate levels, you risk high fish mortality,” said Marzouk.

Done correctly, he adds, intensive fish farming can be very profitable.

But the government has yet to catch up. Concerns over farmers abusing water resources in the desert have made the government slow to endorse desert aquaculture. There's no system in place that would regulate the use of groundwater for aquaculture, leaving the government worried about exhausting the supply, said Marzouk.

But, integrated agriculture requires a culture of responsible water usage, Sadek says: “There's an art of culturing fish that relies on integration. If a client asks me for 100 pounds of tilapia, I tell him to please talk about the land first. How many feddans of oranges or olives do you grow? I would refuse to build just a fish farm. This is a triangle, fish are at the top and crops are the base of the triangle.”