Integrated mangrove-shrimp farming
Integrated mangrove-shrimp farming systems only account for a small percentage of the total shrimp production in Vietnam, due to its low productivity and limited surface area (estimated 50,000 hectares). However, this type of production probably gained more attention than any other form of shrimp production because of its potential to protect mangrove forests rather than clearing them for shrimp pond excavation. Shrimp products from integrated shrimp-mangrove farming systems have long been appreciated by high-end markets for their natural taste and considerable sizes.
In Vietnam, integrated mangrove-shrimp systems are mostly found in the coastal forests in the Ca Mau province, where clearing of mangroves is restricted by law. Many projects have targeted at maintaining these systems by using eco-certification as a tool for conservation. Consequently Penaeus monodon (black tiger shrimp) from integrated farming systems are available with different eco-labels, such as EU organic or Naturland organic. Integrated shrimp-mangrove farms are almost exclusively owned by individual households.
Photo by: Urs Baumgartner
|Average stocking density
|# of crops per year
No clear distinction between crops
|# of days per crop
120 days or longer
All year round
|Type of farmer
- Issues in cold supply chain due to loading/unloading
- Product quality due to isolated location of farms
Type of farmers
The integrated mangrove shrimp farmers are mostly located in the coastal areas of Ca Mau. NGO’s are trying to organize mostly small-scale farmers in cooperatives in order to encourage farmers to learn from each other but also to enable direct linkages between processors and farmer cooperatives. Farm sizes are typically around 3 to 5 ha in size with ponds that cover an entire farm.
Production and harvesting system
Most of the farms practice polyculture with a few crabs, and use sluice gates to take in water during high tide. There are two farming systems:
- integrated systems, where shrimp grow in waterways in-between mangrove vegetation
- separate systems, where shrimp grow in a pond apart from the mangrove vegetation.
According to local legislation all farms must maintain a minimum coverage of vegetation
Partial harvesting happens according to the new and full moon cycle. Though small volumes are harvested every day, main harvests are once in two weeks. The shrimp is trapped in bamboo boxes in the corners of the ponds and harvested according to size.
Grow-out takes 120 days or longer depending on harvest size. Farmers harvest sizes ranging from 4/6 upto 50 HOSO/kg. Farmers tend to harvest larger sizes.
Target species and byproducts
The main target species in integrated mangrove systems are Penaeus monodon (black tiger shrimp), but due to natural water inlets other native shrimp species (pink and white shrimp) and fish species are also able to enter the pond. In some cases farmers also add crabs.
Stocking densities and productivity
Shrimp is mainly stocked naturally during water intake. Farmers stock hatchery PL throughout the year to increase productivity. Stocking densities of P. monodon range from 1 to 6 PL/m2. Annual production averages 350-400 kg/ha.
The other shrimp and fish that have entered the pond during water intake could add up to 50-150 kg/ha/year. If farmers stock crab as well, this would normally be around 500-1000 crabs per hectare. Farmers could harvest around 50-100 kg/ha/year.
Use of seed, feed and other inputs
As mentioned earlier farmers add hatchery P. mondon PL to the pond after water intake. There are many small and large scale hatcheries in Ca Mau but quality of PL varies widely. If farmers have organic certification they can only source PL from hatcheries that have an organic certificate as well. Sometimes PL is first raised in a nursery.
Commercial feeds are not used in these farming systems. Farmers let the shrimp feed exclusively on natural nutrients int he ponds. Farmers normally do not use any chemicals or medicines for pond preparation. They do use natural substances such as tea seed cake to kill predators before stocking the hatchery PL.