OKAYAMA – A Japanese technique for creating artificial river and seawater is expected to enable Cambodian farmers to open three prawn farms this summer — in the mountains.
The artificial water is a blend of fresh water and a carefully measured mix of minerals, including salts of sodium, potassium and calcium.
“This is magic water that enables aqua farming without chemicals. We can turn a mountain village into a fishing village,” said Toshimasa Yamamoto, an Okayama University of Science professor who developed the technique.
Scientists and economists have long believed that upland aquaculture can help solve malnutrition and poverty, but disease has been a hurdle. Yamamoto’s water helps to prevent infections from spreading between farmed animals.
Farmers add about 10 grams of minerals to 1 liter of fresh water — a mixture that produces a slightly salty taste. This produces a medium suitable for aquaculture that costs 10 percent the price of traditional artificial seawater. The technique was patented in 2012.
To date, tiger puffers and eels have been cultivated with the water.
Research has found a reduced incidence of disease because the water has properties that do not exist in nature and lacks the infectious agents often found in seawater and fresh water.
Moreover, fish farmed this way tend to grow faster than in their natural habitat. The university ships tiger puffers six to eight months earlier than those cultivated in seawater.
This growth advantage is believed to stem from fish not having to use as much energy to adjust their osmotic pressure. Such adjustment is necessary when they live in the wild or in conventional fish farms.
The project in the Cambodian province of Takeo will be led by Japan’s overseas aid organization, the Japan International Cooperation Agency. Roughly 30,000 giant river prawns are to be reared at each of three farms from August this year. The prawn sells for eight times the price of fish in Cambodia. JICA will monitor the farms’ efficiency and cost savings.
The water is likely to help spur onshore aquaculture technology in developing countries, said Kenji Kaneko of JICA’s Rural Development Department.
Yamamoto, the technique’s developer, is enthusiastic about the opportunities for his water, which has been dubbed “third water.”
He said the world needs to reduce its dependence on ocean-based aquaculture farms, which can be strongly affected by weather.
There is mostly no need to regulate the water temperature at land-based aqua farms in Cambodia, because temperatures remain high throughout the year. However, Yamamoto recognizes that some countries might need to use electricity to keep temperatures constant for certain fish species. He is studying ways to cut the cost of this by using geothermal and solar heat.
“Aquaculture is possible anywhere if you only have water and electricity,” he said. “In the future, we hope to conduct aquaculture in deserts — and even in space.”