Shrimp culture

SHRIMP CULTURE IN VIET NAM ESP. IN THE MEKONG DELTA

Fish and shrimp have been cultured for a long time in Viet Nam, especially in the Red River Delta, in Mekong Delta and coastal areas. However the methods applied is not so sophisticated until the late 20th century, when fishery demand by processing factories, restaurants…booms and a romantic growing in total acreage has happened so quick that no one could ever know in the past.

This is most evident with data in below tables for shrimp culture in Viet Nam

IMPORTANT SRHIMP SPECIES CULTURED
Although there are some indegineous shrimp species in Viet Nam such as White shrimp (Penaeus merguiensis), Pink shrimp (Penaeus ensis), Cat Tiger (Paraenaeus sculptilis), Yellow shrimp (Metapenaeus joyneri), giant fresh water shrimp (Machrobrandchium rosenbergii) and some of these have been traditionally cultured in some areas of Viet Nam for a long time. Modern farms however has a history not more than 3 decades. The most important species cultured is Black Tiger (Penaeus Monodon), and recently another important species has been cultured-  the new white leg shrimp, or P. vannamei. This species has been introduced into Viet Nam around the year 2000, firstly for experimental trials by some dozen units (the Ministry of Fishery in 2001 granted 9 licenses to import about 48.5 million of P.L  and 5,900 broodstock P. Vannamei for these trials)*. Central and North of Viet Nam are the areas permitted  to culture this species first, then later up to 2008 some provinces in the Mekong Delta were allowed to  limited culture this species in strict control of the provincial government authorities. However this is only the official data, some observers noted that the shrimp was brought into Viet Nam in 2000 illegally from China for culture. In 2002 there is a ban to stock the species in general, however some units got the licenses to stock it.

While the debates whether the white leg shrimp is allowed or not in Viet Nam are still going on by government officials and scientists, a very different scene happened in Thailand. Being tired of the draw-back of the P. monodon for being so susceptible to diseases and annoyed by a strange syndrom (slow to grow syndrom), the farmers switched to P. vannamei. Then in a very short time from nearly nothing in 2002 with P. Vannamei production of less than 25,000 tons, then in 2006 nearly all the shrimp production is from Vannamei (more than 350,000 metric tons)! In the same year, the Black Tiger production is a litter over 20,000 metric tons. This is a miraculous story! During this period we can recall that Viet Nam has issued a ban in 2002, a directive in strick control of Vannamei in 2004, and until 2011, the different opinions still exist in different governent's Ministries'f officials. (Agriculture and Environtment and Natural Resources Ministries).

SHRIMP CULTURE IN VIET NAM
Statistical data by the Viet Nam Ministry of Fishery shows that most of the shrimp farms (in hectares) and production (in metric tons) are in the South of Viet Nam, especially in some provinces in the Mekong Delta. Later on, the shrimp farming expands to other provinces throughout Viet Nam from the Ca Mau Penisula to the Gulf of Tonkin, but this has never changed the production geographically. The South is still the most important shrimp farming region as shown in Table 1 (in hectares) and Table 2 (for total production in metric tons).

But this is not the result of an careless effort. We can see the scientic approaches Thai's farmers applied, from the sophisticated techniques to the top quality P.L used to stock in their ponds.

Table 1: Shrimp ponds in hectares. Source: Viet Nam Ministry of Fishery- Report

Table 2: Shrimp quantity in metric tons. Source: Viet Nam Ministry of Fishery, report

Table 2 (cont.)

The provinces with the biggest shrimp culture in pond acreage are in the Southern-most province, such as Ca Mau Province, Bac Lieu Province, Kien Giang Province, Soc Trang Province and Ben Tre Province.

Total acreage of shrimp ponds in South VN is 476,528ha (2003)
Ca Mau: 224.000 ha
Bac Lieu: 109.258 ha
Soc Trang: 51.044 ha

Distribution of shrimp pond in VN

CULTURE METHODS
In Viet Nam we can see different culture methods as follows.

1. Extensive method culture
The characteristics of a extensive method of shrimp ponds are summerized as follows.
Pond area: 3-5 ha
Ratio of mangrove forest and shrimp pond area: 50-70%/ 50-30 %
Shrimp seed: Natural with some stock
Stock density: 5-7 pc/sq. meter (first cycle)/ 1-1.5 pc/ sq. meter (second cycle)
Culture time: Two cycle per year: from Jan-May/ June-Dec or continuously stocking
No pellet feed
No treatment pond with CaCO2
Time for pond mud bed removing: May-June
Yield: 285 kg/ha/ year

2. Improved Extensive Method the characteristics of which are summerized as follows.
Pond area: 1-3 ha
Water area: 60-70%
Shrimp seed: Natural with some stock
Stock density: 6-7 pc/sq. meter (first cycle)/ 1-2 pc/ sq. meter (second cycle)
Culture time: Two cycle per year: from Jan-May/ June-Nov
Some pellet feed or self-processed feed
There is pond treatment with CaCO2 and fertilizers
Time for pond mud bed removing: May-June
Yield: 195 kg/ha/ cycle

3. The semi-intensive and intensive method the characteristics of which are summerized as follows.
Pond area: 1-4 ha
Water area: 70-75%
Shrimp seed: artificial hatchery shrimp seeds stocking
Stock density: 15-45 pc/sq. meter
Culture time: Two cycle per year: from Jan-May/ June-Nov
100% pellet feed
There is pond treatment with CaCO2 and fertilizers
The use of chemical and enzymes
Yield: 1 to 3 metric tons (semi intensive) and 5-7 metric tons (intensive)

4. The forest-shrimp-crab combine-culture method
Based on an investigation made by Can tho University in four Mekong coastal provinces, this culture type is very common at the ratio of 38.9% as compared to other types. Charateristics of this culture are as follows.:
Culture area (with mangrove forest inside): 3-5 ha
Surrounding canal water area: 25-30%
Shrimp seed: artificial hatchery shrimp seeds stocking, natural crab and fish
Shrimp density: 12 pc/sq. meter (1st cycle), 1.5-2 (2nd cycle)
Crab density: 0.1- 0.2 pc/sq meter
Culture time: One crop per year (July to Feb)
No pellet feed
No CaCO2 or/and fertilizers
Yield: 580 kg/year (shrimp, crab, fish)

5. The rice and shrimp culture method
This method is seen in the rainy season when there is enough fresh water, farmers grow rice. When the dry season coming, the water becomes salty, they raise shrimp on the that once growing lands. The characteristics are as follows.
Culture pond area: 1-2 ha
Surrounding canal water area: 25-30%
Water deep on rice bed: 30-50 cm
Shrimp seed: artificial shrimp
Shrimp density: 2-5 pc/sq. meter
Culture time: Jan- May
Pellet feed or self processed feed
CaCO2 or/and fertilizers used
Yield: 300-45- kg/year

Some shrimp culture types above are specific to the Mekong Delta as investigated and reported by Can Tho University. Type 1, 2 and 3 however are common to many shrimp raising countries. Type 5 (rice-shrimp) applies for areas where rice growing and shrimp raising can be carried on depending on the season. These areas are usually relatively far from the beach (refer to the salinity map of Mekong Delta, areas in yellow and blue).

For type 4 (mangrove forest, fish and shrimp) is seen in areas where salinity is availabe nearly the year round- more than 6 months (the coatal areas, pink color on the map) so the rice growing is not suitable.

SALINITY IN THE MEKONG DELTA
Although there are five types of shrimp culture mentioned here, for practical purpose in general there are three main culture methods: the extensive, the semi-intensive and the intensive culture methods.

Bac Lieu is the second largest in shrimp farming area with favorable conditions for shrimp farming. The exact statistic data is difficult to get, but it is believed that in Bac Lieu the shrimp pond surface can reach 120,000 ha or more. Of this nearly 20,000 ha of ponds are intensive or /semi-intensive ponds, the other are extensive ponds with relatively low yield per year.

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* See http://www.fao.org/docrep/007/ad505e/ad505e09.htm