World Aquacluture Magazine - September 2020

WWW.WA S.ORG • WORLD AQUACULTURE • SEP TEMBER 2020 19 Artemia farming is conducted in modified salt ponds during the dry season. Once evaporated seawater reaches a salinity of about 80 g/L, all Artemia predators die and freshly- hatched Artemia in the first nauplius stage can be inoculated. Artemia feeding is managed by direct or indirect fertilization of the culture pond with manure (most commonly chicken manure) in combination with inorganic fertilizers (e.g., urea and di-ammonium phosphate) to produce green water as suitable food for Artemia. Occasionally ground rice bran is added as supplementary food. After inoculation, Artemia completes its life cycle within 10-12 days. At maturity, Artemia females release their first offspring as either nauplii in an ovoviviparous mode of reproduction or resting eggs/cysts in an oviparous mode. Cyst production will continue for a couple of months provided suitable food is available and water temperature is not too extreme. Throughout the 4-mo dry season, Artemia can produce up to 50-60 kg (wet weight) of cysts per hectare in conventional systems (Fig. 3). Successful production in the Vinh Chau field station opened the way for an Artemia extension program to salt farmers in the coastal area of Soc Trang and Bac Lieu provinces when cyst demands quickly increased, not only for local aquaculture activities but also for export markets. However, Artemia was new to local salt farmers and it took a lot of effort (Fig. 4) to convince salt farmers that integrating Artemia culture might not harm their salt production and that it is more profitable than traditional salt production. The Artemia field station in Vinh Chau became an important training center for salt farmers. Local TV and radio stations helped by propagating information about these new farming opportunities. D uring the late 1970s and early 1980s, Vietnamwas faced with difficulties for economic development. Among those difficulties were a critical lack of knowledge and expertise in aquaculture. In the Mekong Delta traditional aquaculture used the tidal differences to stock ponds with wild seed taken in with freshwater, brackishwater or seawater from the Mekong River. The indigenous freshwater prawn Macrobrachium rosenbergii was designated as a target species because of its high potential for the export market and several years were required before local institutions were able to master hatchery techniques. However, the difficulty of importing expensive Artemia cysts became the main bottleneck for further expansion of prawn farming in the Mekong Delta and elsewhere in Vietnam. In the early 1980s, Cantho University, with the technical and financial help of Ghent University (Belgium) and KWT (The Netherlands), made plans to set up Artemia pond production, following successful trials in the Philippines and Thailand. In 1986 Artemia franciscana (San Francisco Bay strain) was introduced to the Vinh Chau solar saltworks (Fig. 1) with the aim of producing Artemia cysts for use as starter food in the hatchery production of Macrobrachium. All Artemia trials were conducted at the Vinh Chau field station (Fig. 2) of Cantho University. Supported by different development cooperation projects, numerous M.Sc . and Ph.D. studies explored the production potential of different culture systems (e.g. static, flow- through, monoculture, integrated, one-cycle, multi-cycle). The main focus was on cyst production as this was the main commodity of interest for local aquaculture hatcheries, initially those for freshwater prawn, but later for penaeid shrimp, Asian seabass and mud crab. State of the Art of Brine Shrimp Artemia Production in Artisanal Saltworks in the Mekong Delta, Vietnam Nguyen Van Hoa, Le Van Thong and Patrick Sorgeloos ( C O N T I N U E D O N P A G E 2 0 ) FIGURE 1. Artemia started in Vinh Chau salt cooperative in Soc Trang province, Vietnam. FIGURE 2. Artemia field station (Soc Trang province, Vietnam) of Cantho University in the Vinh Chau solar saltworks.

RkJQdWJsaXNoZXIy MjExNDY=