Artemia immigrated into Viet Nam since the early 1980s in the form of brine cysts to be used as feed for giant freshwater prawn. In 1984, Department of Maritime Products of Cần Thơ University has successfully experimented culturing Artemia in lab condition for the production of feed for giant freshwater prawn. Subsequently, in 1986, Application Center of Department of Maritime Products of Cần Thơ University, located in Vĩnh Châu town (formerly Vĩnh Châu district) has experimented culturing of Artemia for cysts and biomass. lấy trứng và sinh khối. After the experimentation, in 1989, the procedure of culturing Artemia for brine cysts has become consistent and transferred to saltmakers cooperatives of tại Vĩnh Phước and Lai Hòa communes of nowadays Vĩnh Châu town, Sóc Trăng province. In 1991, Artemia has adapted to the culturing environment, the production procedure on salt fields has been stabilized and it has been produced in throughout Vĩnh Châu town and Bạc Liêu province. Since 1996, Artemia has been produced concentratedly in the communes of Vĩnh Tân, Lai Hoà and Vĩnh Phước ward of Vĩnh Châu town, Bạc Liêu province. This is the geographical area corresponding to the geographical indication “Vĩnh Châu” Artemia. 

“Vĩnh Châu” Artemia brine cysts are deeply brown and dry. The sizes are consistent and has incomplete spherical shape when observed under microscope. When hatched, the shell will quickly float. The size of “Vĩnh Châu” brine Artemia cysts is smaller than 45 µm, unsaturated fatty acid content is no higher than 17 mg/g. With the small sizes of cysts and larvae, and the high content of unsaturated fatty acid (HUFA), “Vĩnh Châu” brine Artemia cysts are highly valued on global markets  as “Vĩnh Châu” Artemia hatchlings are suitable to the digestive systems of many types of shrimps’, fishes’, etc. hatchlings. 

In Viet Nam, brine Artemia cysts are categorized by product origin. Among those, Artemia of “Vĩnh Châu” yields the highest price. 

 

  

Aside from brine cysts, “Vĩnh Châu” Artemia biomass is also a trusted product by maritime producers. Artemia biomass is produced from mature Artemia, and used as feed for prawns, pleasure and commercial fishes, crabs, shellfishes, etc. It is sold in two forms: frozen and dried biomass. Frozen “Vĩnh Châu” Artemia biomass has brown-yellow colour, while dried Artemia biomass has deep brown colour, and pressed into patches. 

         

Frozen “Vĩnh Châu” Artemia biomass’ content includes: Protein 46.6 - 52.9 %, Lipid 6.3 -11.8 %, total fatty acid 84.6 - 98.3 mg/g DW. Dried “Vĩnh Châu” Artemia biomass’ content includes: Protein 44.0 - 52.7%, Lipid 6.0 - 13.2 %, total fatty acid 84.6 - 99.6 mg/g DW. 

Artemia cultured in Vĩnh Châu is of the Artemia franciscana (SFB) strain originated in the U.S. After over 30 years of development (up to 2020), the SFB strain has essentially become an indigenous as the existence and development of descendants having different traits to their ancestors. These differences include: (1) Artemia of Vĩnh Châu can withstand heat better than the original SFB ; (2) the brine cysts can have lower salinity; (3) the sizes of Vĩnh Châu brine cysts and hatchling are 5 - 6 % smaller than the original strain. These differences are due to the natural conditions of Vĩnh Châu as well as the experiences in culturing Artemia of the locals. 

Vĩnh Châu is a town of Sóc Trăng province, under the influence of the tropical monsoon climate. The geographical area has the annual average temperature of 26.08 °C, the hottest month being April with the monthly average temperature of 28 °C, and the coldest month being December and with the monthly average temperature of 25.2 °C. The dry season in Vĩnh Châu lasts from December to April with 1% of total annual rainfall. This is an important factor for local producers to prepare saline water and Artemia culturing season. 

The Artemia production area in Vĩnh Châu was a longstanding saltmaking area, which started transitioning to Artemia culturing in 1986 and expanded in 1989. The area is divided into lots, making it easier to prepare saline water. 

Artemia culturing season starts in December and lasts until May. During the season, the elements of strain, culturing ponds, harvest, processing, and preservation are vigorously managed and monitored. 

The strain of Artemia used in Vĩnh Châu is the indigenous strain. Artemia hatchlings are inserted into the culturing pond in stage Instar I. Water salinity and temperature are maintained at 80 - 100 ‰ and 28 - 32 °C respectively. 

Artemia are filter feeders, they eat continuously, even when sleeping. Therefore, maintaining the amount and quality of microalgae is a decisive factor to the development and unsaturated fatty acid content of Artemia. 

The soil for culturing Artemia is coastal saline soil, the pH level of the soil is 8 – 8.5, the pH level of the water is over 6, which is highly suitable for the development of microalgae. Environmental analysis results show that the percentage of Nannochloropsis in culturing ponds of Vĩnh Châu is approximately 50 - 75% of total number of microalgae, Chaetoceros accounts for approximately 25- 50% of total number of microalgae. 

In Vĩnh Châu, when the density of Artemia in a pond gets higher (the belly is not filled and water transparency is >35cm), Artemia producers will provide organic fertilisers, rice bran, milled soya, flour or industrial feed specific for Artemia. 

To optimise the use of feed, Artemia producers in Vĩnh Châu use chain rakes to rake the pond bed and banks once or twice per day. Raking regularly will eliminate algae mat (lab-lab), increase the oxygen level in water, mitigate the dissolved oxygen level in the bottom, especially in early morning due to the biological respiration of the algae. Moreover, raking will stir up the feed in pond bed, making them float around the water, and can be utilized as additional feed for Artemia. 

The abundant and diverse feed explains the high amount of unsaturated fatty acid in “Vĩnh Châu” Artemia. 

“Vĩnh Châu” Artemia brine cysts are harvested 15 - 23 days after Artemia hatchlings are inserted into the pond. Producers use 125µm filter to harvest floating cysts. From their experiences and the support from scientists from Cần Thơ University, producers in Vĩnh Châu use water with the salinity of 250 - 300‰ to organically dehydrate the cysts and remove impurities. Thanks to the technique, the hatch sequence of Artemia brine cysts cultured in Vĩnh Châu is faster, and the shell will quickly float to the surface. 

“Vĩnh Châu” Artemia biomass is harvested by thinning mature Artemia when the density in the pond is too high or when Artemia completes its reproduction cycle. The producer uses scoops or nets to harvest the biomass and clean it with saline water. The fresh biomass is then left for dry and frozen at -25 °C to -30 °C to create frozen biomass product. For dried biomass, the fresh biomass is dried using sunlight or dryer to put moisture under 10% and stored in vacuum bags. 

The specific and favourable natural conditions, combining with the technique and know-hows from the scientists as well as the experiences of Artemia producers have resulted in the well-known Artemia of Vĩnh Châu, trusted by maritime producers. 

  

Center for Examining Geographical Indication and International Trademark