Farmers in Cà Mau Province, on the southern tip of the Mekong Delta in Vietnam, have begun to breed the giant freshwater prawn, or Rosenberg shrimp (Macrobrachium rosenbergii), in rice fields and have earned excellent profits in recent years. One rice farmer said he made three times his annual rice crop profit from three months of farming the prawn.
Many of the catches are sold IQF into the U.S.A., but small amounts are flown in fresh to Europe for Christmas, where they fetch gigantic sums. Labeled Rosenberg shrimps, the common name in Europe, they have been known to fetch more than EUR 100 (USD 108) per kilo in high-end department stores.
According to Cà Mau Province’s Department of Agriculture and Rural Development, Thới Bình, U Minh and Cái Nước districts, and Cà Mau city, are estimated to have 12,000 hectares (ha) of rice fields where the prawn is farmed after the rice has been harvested. Thới Bình alone accounts for nearly 10,800 ha, up 3,000 ha from last year.
Trần Văn Phước in Thới Bình’s Biển Bạch Đông Commune told Vietnam News he began breeding the prawns in 2014. In his first crop, he harvested 3,000 prawns per hectare and earned a profit of nearly VND 20 million (USD 880, EUR 820) after three months.
The crustaceans are easy to breed, and their harvest time depends on how they are tended, according to the farmer. If they are given additional food they can be harvested after 85 to 95 days of breeding, he said.
Nguyễn Phi Thoàn, deputy chairman of the Biển Bạch Đông Commune People’s Committee, said past success had persuaded many farmers to expand their prawn farming areas this year. His commune has increased its farming area by 600 ha to 2,200 ha, making it the largest giant freshwater prawn breeding area in the district.
Nguyễn Hoàng Lâm, head of the Thới Bình Bureau of Agriculture and Rural Development, said the method of intercropping the prawns in rice fields had been assessed as effective and sustainable, since there had been no disease outbreaks.
The average yield of giant freshwater prawns is 150 to 220 kilos per hectare. At VND 130,000 to 150,000 (USD 5.70 to 6.60, EUR 5.30 to 6.20) per kilo, farmers can earn a profit of VND 20 to 30 million (USD 880 to 1,320, EUR 820 to1,230) per hectare, Lâm said. The Thới Bình bureau has recommended that farmers expand the farming areas, he added.
Cà Mau Province, Vietnam’s largest shrimp producing province, has developed methods of farming shrimp that offer high yields and are sustainable, according to its Department of Agriculture and Rural Development. They include advanced extensive farming, industrial farming, rotating shrimp and rice in rice fields and breeding shrimp in submerged mangrove forests.
The province has more than 175,800 ha devoted to shrimp farms, with advanced extensive farming accounting for the largest area of 85,099 ha. The average yield is 540 kilos of shrimp per hectare. Currently key varieties being farmed are black tiger shrimp (Penaeus monodon) and white-legged shrimp (Penaeus vannamei), and the giant freshwater prawn on a seasonal basis.
The giant freshwater prawn can be only farmed in flooded rice fields for a limited time of three months around Christmas when the rice harvest is over. However, the Vietnamese government plans to develop all year round aquaculture with this species.
The Cà Mau Province’s Department of Agriculture and Rural Development had planned to rotate rice and shrimp on 50,960 ha of rice fields this year. However, farmers have bred shrimp on only around 30,000 ha because of the drought and the high salinity of water from the Mekong River earlier in the year.
Farmers growing the two crops allow what is always brackish water from the Mekong River to enter their fields during the dry season in order to breed shrimp before switching to rice in the rainy season.
It depends on how high the salinity is as to what kind of shrimp they can grow and how long it takes. The more saltwater, the stronger the shrimp get, but the longer it takes to grow them. So they can use their rice fields for farming black tigers if the salinity is right and if it is low, then they farm giant freshwater prawns.
In order to sustainably develop shrimp farming, Cà Mau Province has adopted comprehensive measures such as reviewing farming schedules and identifying shrimp species suitable for breeding and meeting the market’s needs. It has also stepped up inspection of shrimp feed and broodstock and provided the province’s advanced training to farmers.
In October, the Vietnamese government decided to further shrimp farming in Cà Mau Province with advanced farming techniques to produce “clean shrimp with high competitiveness at home and abroad.”