The production site of black tiger shrimp (giant tiger prawn), long familiar on Japanese tables as \"black shrimp,\" is quietly undergoing a generational shift. The stage is Ca Mau province in the Mekong Delta, at the southernmost tip of Vietnam. One result recorded at a small farmer's farming pond beside a rice field shows the possibility of overturning the weakness of \"unstable supply\" that has long dogged this species. Rather than relying on wild broodstock and post-larvae, it raises domesticated lineages in two stages\u2014let us read this plain but steady practice from the viewpoint of Japanese procurement and aquaculture.<\/p>\n
Nguyen Van Phong, who handles both rice and shrimp in the Kinh 5B hamlet of Tri Phai commune, Ca Mau province, this time stocked about 20,000 \"domesticated black tiger (tom su gia hoa).\" The grow-out period was a little over two months. On harvest, the size was around 35 pieces\/kg and the survival rate about 85%\u2014meaning roughly 17,000 survived\u2014with shipped volume exceeding 400 kg. Across the whole operation combined with rice farming, household annual income reaches about 200 million dong (roughly 1.2 million yen or so).<\/p>\n
Lined up as figures alone, it may look plain. But the more one knows black-shrimp farming, the more this survival rate of 85% catches the eye. In conventional extensive farming using wild post-larvae, whether they survive is largely left to luck, and it was not unusual for most of the post-larvae put into a pond not to make it to shipment. Phong cites as factors of success the pond's advance preparation, treatment of the water environment, and watching over the technical figures. On the domesticated lineage itself, he speaks of the sense on the ground: \"high environmental adaptability, good survival, and a shorter rearing period.\"<\/p>\n
Black tiger was the star that led Asian aquaculture in the 1990s. But it ceded the lead role to the spread of disease and the rise of the easier-to-manage vannamei (whiteleg shrimp). Behind that was a structural weakness in seed supply.<\/p>\n
In Vietnam, securing black-shrimp broodstock has long depended on wild individuals caught in natural waters. Wild broodstock have unreadable genetic provenance and carry the risk of bringing in disease. The route by which post-larvae taken from sea-caught parents carry pathogens through hatcheries into farming ponds lay at the root of the whole industry's instability. Vietnam is still said to import tens of thousands of pairs of broodstock a year at US$20\u201360 per pair, but the reality is that their quality can hardly be verified.<\/p>\n
\"Domestication (gia hoa)\" refers to the effort to cut off this reliance on the wild. Disease-free (SPF), fast-growing broodstock are raised under lineage management on land, and post-larvae of stable quality are supplied on a planned basis. The biggest reason vannamei won out in the world market lay in this domestication of seed, and the current trend is to realize it for black shrimp too. Domesticated black-shrimp lineages that began with Hawaii-origin breeding have gone through generations, improved to the point where growth speed approaches vannamei. Within Vietnam, demand for domesticated broodstock is projected to grow from about 60,000 in 2022 to a scale of 150,000\u2013200,000 by 2030. Phong's pond can be called on-the-ground evidence that this large trend has reached even a single farmer in the Mekong Delta.<\/p>\n
Another key is the two-stage farming (nuoi hai giai doan) Phong adopted. This is a method of not releasing post-larvae straight into a wide grow-out pond but first growing them in a small nursery pond under management for about 15\u201320 days, and moving them to the full-scale grow-out pond only after they have become somewhat sturdy.<\/p>\n
The aim is clear: to get through the most death-prone early weeks in a small pond where the eye reaches and water is easy to control. Weak individuals and disease can be culled and detected at this stage, and by the time they move to the main pond only highly viable individuals remain. The sturdy domesticated lineage and the two-stage method that carefully protects the early period\u2014this combination can be seen as the two wheels that supported the 85% survival rate.<\/p>\n
This method is not Phong's own invention alone; it is spreading across Ca Mau province. For example, in Tan Phu commune in the same province, 12 households took on a two-stage model of improved extensive domesticated black shrimp across 30 ha in early 2023, and in a cooperative in another hamlet, 30 households across 40 ha are reported to have earned income of several million to 20 million dong a month. In two-stage extensive farming combined with seaweed (ogonori, Gracilaria), there are also reports that yield per unit area clearly exceeded conventional extensive farming. This technology's current position is one of spreading as an area, not a point.<\/p>\n
Lining up Phong's case with the conventional extensive farming that relied on wild post-larvae reveals what the domesticated lineage plus two-stage method changed.<\/p>\n