Saphira Prawn
The Saphira prawn, also known as the giant freshwater prawn (GFP) or Rosenberg Shrimp, a marketing name common in Europe, is one of the most important freshwater crustacean species in many tropical and subtropical countries’ inland aquaculture sectors. Freshwater prawn farming has grown rapidly around the world since the 1990s, especially in Asian countries.
The Saphira prawn is one of the world’s largest prawns. Its fine lobster-like flavor, combined with a delicate and lightly crunchy flesh and the fantastic juice of its orange coral (roe), makes it a highly praised commodity among fine gourmets. The Saphira gets its name from its majestic claws, which are a stunning deep sapphire blue color in adulthood. And when it is cooked, it changes and takes on a fiery red color.
China is the world’s largest producer of GFP, accounting for roughly 29% of global production, followed by India, Thailand, Bangladesh, and Taiwan. While Việt Nam is not currently a major producer of GFP, production is growing. GFP has become a popular aquaculture species in Việt Nam due to its fast growth rate, which allows it to hit market size in 6 to 8 months. GFP thrives on a low-protein, low-cost diet and commands a high market price, with strong demand in both domestic and export markets. In Việt Nam, GFP is cultured in a variety of culture systems, typically in integrated or rotational rice-prawn culture, and has become one of the most common farmed aquatic species in the country.
Saphira prawns are primarily produced in the provinces of Cà Mau, Kiên Giang, and Đồng Tháp in the Mekong Delta. As part of a crop-rotation model, prawns are bred in the dry season and rice is grown in the wet season on the same field. According to the district’s Department of Agriculture and Rural Development, the shrimp-rice rotation model has proven to be very successful. Since farmers use less or no pesticides, the shrimp bred under this model are considered “natural” and environmentally friendly.
Saphira prawns, including carp, tilapia, barbs, and catfish, are well-suited to freshwater polyculture because they need very little input and cost. The prawns consume pests and other insects, increase soil fertility, and feed on the seeds of common rice-field weeds, while the rice absorbs the nutrients released by the Saphira prawn, resulting in improved rice-field water quality.
Females reach 25cm while the larger males top out 32cm, excluding their impressive claws which can breach 60cm. Males are divided into three types: small males have short translucent claws, mid-sized orange claws have large yellow-orange claws as long as their bodies, while large blue claws have bright blue claws twice as long as their bodies. Blue claws dominate orange claws, while small makes sit at the bottom of the heap.
Wild Saphira prawns live in shallow, muddy lakes and rivers with good vegetation. They can crawl on land and even up relatively vertical surfaces like waterfalls, they are largely active during the night and sleeping during the day – spending days half-buried in mud and detritus. As night falls, they forage and hunt for worms, crustaceans, molluscs, fish, and carrion. People have caught and eaten Saphira prawns for thousands of years in Asia but modern farming began just a half-century ago.
The yield of wild prawns based on conventional fishing changes throughout the year. Saphira prawn appears to reproduce all year round, but major peaks occur between April and June and between August and October. Vietnamese government plans to develop all-year-round aquaculture with this species. Farmers growing the two crops allow what is always brackish water from the Mekong River to enter their fields during the dry season to breed shrimp before switching to rice in the rainy season.
Via government-funded research with the Research Institute for Aquaculture in South Việt Nam to improve growth rates of the giant freshwater prawn. Three giant freshwater prawn strains from Việt Nam and Thailand were merged into a single breeding stock by Vietnamese scientists. This breeding program led to a significant breakthrough with an improved culture strain that grows 25 percent faster than regular strains.
Postharvest & Processing
A study has shown that the best way to preserve the freshness and improve the texture of Saphira prawns is treated with liquid nitrogen quick-freezing (−195.79°C). Moreover, it prolonged shelf life by up to 4 to 8 weeks compared with -35°C air-blast freezing and -18°C refrigerator direct freezing.
When harvesting and processing Saphira prawns, the farmer must be cautious not to smash their internal organs due to improper harvesting, transportation, and storage. Saphira prawns can’t be piled or stacked like other shrimp because their internal organs are susceptible to damage, lowering meat quality significantly. It recommends icing and washing Saphira prawn in chlorinated water immediately upon harvest, right by the pond’s edge.
Threats
Two of the biggest challenges today are drought and the high salinity of water from the Mekong River. 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.
Drought and the high salinity of Mekong River water are two of the most pressing issues today. What kind of shrimp they will grow and how long it takes depends on how high the salinity is. The shrimp gets stronger when exposed to more saltwater, but it takes longer for them to mature. 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.
Bến Tre is one of its coastal provinces, which have been hardest hit. The worst affected areas are in Thạnh Phú, Giồng Trôm, and Mỏ Cày Nam districts. Many farmers are facing losses due to saltwater intrusion, which is killing the crustaceans. In the past, the salinity rate would never exceed 1.7 percent, and giant river prawns could withstand it, but in recent years the salinity rate has exceeded 2 percent and most of the prawns will likely be unable to survive under this condition.
Despite the potential for expanded production, the sustainability of freshwater prawn farming in the region is currently threatened by low production efficiency and vulnerability of farmed stocks to disease. Commercial large-scale and small-scale GFP farms in Việt Nam have experienced relatively low stock productivity, large size and weight variation, a low proportion of edible meat (large head to body ratio), scarcity of good quality seed stock.
Another challenge is that Saphira prawns are familiar mostly to Asian consumers, rather than being established in a truly global market. Unlike white-leg shrimps and tiger prawns, Saphira prawns have yet become mainstays of the global seafood industry.
Solutions
It is necessitated to 1) improve nursery techniques for artificial juvenile prawns to provide larger, healthier juveniles for stocking activities; 2) improve feed technology based on the use of available agricultural by-products so that farmers can lower their costs of conducting prawn culture, and 3) develop a means of transferring new technical knowledge to farmers.
Better marketing and packaging of the species, similar to how pangasius (Striped catfish) was globally marketed as “cream dory” or “basa fish,” may help boost a global marketing strategy and increase market awareness and acceptance. As an easier and faster-to-produce alternative to marine lobsters, terms like “blue shrimp” or “blue prawn” – or even “river lobster” – have been suggested.
