Development of Marine Shrimp Farming Models

less effective to marine shrimp farming. Shrimp farming output gradually increased, in which Long An had the largest increase rate, followed by Tra Vinh and Soc Trang (Table 2.3).

Table 2.2: Shrimp farming area of the Mekong Delta (1999-2005) (ha)

Conscious

1999	2000	2001	2002	2003	2004	2005	2005/1
								999
Long An	1,320	1,709	3,236	3,530	4.221	5.133	6,100	4.62
Tien Giang	2,850	2,498	2,617	2,949	3,338	3,439	4,000	1.40
Ben Tre	20,145	28,363	27,273	29,402	27,818	32,368	32,478	1.61
Tra Vinh	6.361	10,122	11,445	13,547	15,072	18,800	20,000	3.14
Hau Giang					6	22	68
Soc Trang	27,628	32,930	48,060	41,869	49,548	48,856	45,000	1.63
Bac Lieu	27,186	45,748	84,891	96,119	109,258	115,659	116,473	4.28
Ca Mau	77,000	105,000	190,000	202,000	226,299	231,110	236,255	3.07
Kien Giang	9,327	12,520	26,800	38,000	51,044	67,725	74,771	8.02
Mekong Delta	171,817	238,890	394,322	427,416	486,604	523.112	535.145	3.11

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(Source: BTS, 2006)

Table 2.3: Shrimp farming output of the Mekong Delta (1999-2005) (tons)

Conscious

1999	2000	2001	2002	2003	2004	2005	2005/
								1999
Long An	330	585	1,621	2,185	4,219	4,067	7690	23.30
Tien Giang	1,115	1,174	1,405	2,876	4,322	6,297	8,000	7.17
Ben Tre	7,550	10.101	11,000	15,906	12,731	20,561	26,300	3.48
Tra Vinh	1.625	2,500	4,100	4,880	7,500	12,000	20,010	12.31
Hau Giang					1	4	30
Soc Trang	4.231	12,408	15,858	15,980	22,356	27,407	34,000	8.04
Bac Lieu	5,939	9,500	27,700	37,392	54,731	72,209	63,610	10.71
Ca Mau	26,000	35,700	55,330	60,619	62,241	72,936	83,860	3.23
Kien Giang	1,062	1,764	4,800	6.675	10,183	15,228	20,060	18.89
Mekong Delta	47,852	73,732	121,814	146,513	178,284	230,709	263,560	5.51

(Source: BTS, 2006)

However, Tien Giang province has the highest shrimp productivity of 2 tons/ha, followed by Long An (1.26 tons/ha) and Tra Vinh (1.00 tons/ha). This result shows that these provinces have a higher level of intensive farming than other provinces (Tables 2.4 and 2.5) (BTS, 2006).

The productivity of farmed shrimp did not increase in 2000-2001 because farmed shrimp were affected by disease in the early stages of the conversion of agricultural land to marine shrimp farming in the Mekong Delta (Table 2.5).

Table 2.4: Shrimp farming productivity in the Mekong Delta from 2001-2005 (tons/ha)

Province 1999 2000 2001 2002 2003 2004 2005 2005/

1999

Long An

0.25	0.34	0.50	0.62	1.00	0.79	1.26	5.04
Tien Giang	0.39	0.47	0.54	0.98	1.29	1.83	2.00	5.11
Ben Tre	0.37	0.36	0.40	0.54	0.46	0.64	0.81	2.16
Tra Vinh	0.26	0.25	0.36	0.36	0.50	0.64	1.00	3.92
Hau Giang					0.17	0.18	0.44
Soc Trang	0.15	0.38	0.33	0.38	0.45	0.56	0.76	4.93
Bac Lieu	0.22	0.21	0.33	0.39	0.50	0.62	0.55	2.50
Ca Mau	0.34	0.34	0.29	0.30	0.28	0.32	0.35	1.05
Kien Giang	0.11	0.14	0.18	0.18	0.20	0.22	0.27	2.36
Total of Mekong Delta	0.28	0.31	0.31	0.34	0.37	0.44	0.49	1.77

(Source: BTS, 2006)

Table 2.5: Total area, output and productivity of shrimp farming in the Mekong Delta, 2005

Province Area (ha) % Rank

class

Output (tons)

% Rank

class

Yield (ton/ha)

Rating

Long An

6,100	1.14	7	7,690	2.92	8	1.26	2
Tien Giang	4,000	0.75	8	8,000	3.04	7	2.00	1
Ben Tre	32,478	6.07	5	26,300	9.98	4	0.81	4
Tra Vinh	20,000	3.74	6	20,010	7.59	6	1.00	3
Hau Giang	68	0.01	9	30	0.01	9	0.44	7
Soc Trang	45,000	8.41	4	34,000	12.90	3	0.76	5
Bac Lieu	116,473	21.76	2	63,610	24.13	2	0.55	6
Ca Mau	236,255	44.15	1	83,860	31.82	1	0.35	8
Kien Giang	74,771	13.97	3	20,060	7.61	5	0.27	9

(Source: BTS, 2006)

2.1.2. Development of marine shrimp farming models

In 2005, low-investment marine shrimp farming models such as extensive and improved extensive farming dominated 88.8% (536,863 ha) of the total marine shrimp farming area of the country. The Mekong Delta accounted for about 468,855 ha (90.9% of this area). Low-investment black tiger shrimp farming models such as shrimp-forest farming accounted for 256,112 ha, of which Ca Mau province had about 200,255 ha. Shrimp-rice had about 121,739 ha (Ca Mau:

35,000 ha, Kien Giang 46,371 ha and Bac Lieu 24,823 ha) (Figure 2.1).

The total area of intensive shrimp farming nationwide was 7,367 hectares in 1999, reaching 67,616 hectares in 2005, accounting for 11.2% of the area. The proportion of intensive shrimp farming area in the South Central provinces accounts for about 79.4% of this region (11,432 hectares of intensive farming out of a total of 14,391 hectares of marine shrimp farming area in this region), higher than the Mekong Delta region by 9.02% (48,290 hectares). Although the proportion of intensive marine shrimp farming area in the Mekong Delta is lower than other regions in the country

However, the total farming area of this model accounts for 71% of the total intensive shrimp farming area of the country (BTS, 2006).

The area of marine shrimp farming in the Mekong Delta increased rapidly in 2002-2003, then increased slowly. In the marine shrimp farming development plan, the area of marine shrimp farming in the Mekong Delta accounted for an average of 10% in 2010 (BTS, 2003).

BTC/USD

48,290

QC/QCCT

109,004

Shrimp-rice

121,739

Shrimp-forest

256,112

50,000 100,000 150,000 200,000 250,000 300,000

Figure 2.1: Area of marine shrimp farming models in the Mekong Delta, 2005

2.1.3. Situation of marine shrimp seed production in the Mekong Delta

Before 1990, shrimp seed production was not successful in Vietnam, so natural shrimp seeds were used, so shrimp farming did not develop. From 1990-1995, shrimp seed production was successful and concentrated in the South Central provinces such as Khanh Hoa and Ninh Thuan, bringing about strong development of shrimp farming in the whole country.

However, the quantity and quality of marine shrimp seed have not yet satisfied the development needs of commercial shrimp farming, because the demand for seed is concentrated in the short period before the shrimp farming season. The broodstock depends on wild exploitation and small-scale hatcheries. The transportation of most shrimp seed from the Central provinces to the Mekong Delta has limited the ability to control the quality of seed.

Table 2.6: Number of production farms and PL (2001-2005) (million heads)

2001 2002 2003 2004 2005

Provinces of Production

quantity			quantity		quantity		quantity		camp	quantity
Delta	18	101	28	179	33	404	35	608	37	775
BTB	28	136	61	329	91	531	115	707	89	639
NTB	2,624	10,514	3,519	13,263	3,532	14,750	3,447	14,203	2,582	13,801
Southeast Asia	269	1,520	297	1,907	325	2,583	312	2,627	312	2,414
Mekong Delta	865	4,061	1,026	4,068	1,094	8,406	1,162	7,898	1,261	11,176
Total	3.804	16,332	4,931	19,746	5,075	26,674	5,071	26,043	4,281	28,805

Number of camps

Number of farms

Product

(Red River Delta: Red River Delta, North Central Coast: North Central Coast, South Central Coast: South Central Coast)(Source: BTS, 2006)

In 2002, the demand for shrimp seed in the Mekong Delta provinces was 13.5 billion shrimp seeds while the supply capacity was only 4.1 billion, so the region had to import shrimp seed from surrounding provinces, accounting for about 52.2% (BTS, 2003). In 2005, the whole country produced 28.8 billion shrimp seeds with 4,281 hatcheries. The South Central provinces produced 13.8 billion shrimp seeds, accounting for 47.9% of the country's total, followed by the Mekong Delta provinces at 38.8% (11.2 billion). The Mekong Delta provinces had the highest demand for shrimp seeds in the country, but the hatcheries could not meet the demand, so they had to import from the South Central provinces (BTS, 2006) (Table 2.6).

According to BTS (2003), the supply capacity of shrimp hatcheries in the Mekong Delta only met 50% of the total demand for shrimp hatcheries in the region in 2010. The difficulties of shrimp hatcheries in the Mekong Delta are due to unsuitable environmental conditions, high costs, and difficulty competing with hatcheries in the South Central provinces. Although the number of hatcheries has decreased slightly, the supply of hatcheries has increased due to increased technical efficiency. In the Mekong Delta, the number of hatcheries and hatcheries have both increased (Figures 2.2 and 2.3).

6,000

4,000

2,000

Mekong Delta

Nationwide

Mekong Delta

Nationwide

1999 2000 2001 2002 2003 2004 2005

48 507 865 1,026 1,094 1,162 1,261

2,021 2,763 3,804 4,931 5,075 5,071 4,281

Year

Figure 2.2: Development of hatcheries in Vietnam and the Mekong Delta, 1999 - 2005

1999	2000	2001	2002	2003	2004	2005



	7,780	11,447	16,332	19,746	26,674	26,043	28,805

35,000

30,000

25,000

20,000

15,000

10,000

5,000

Mekong Delta

Nationwide

Year

Mekong Delta

Nationwide

427 2,385 4,061 4,068 8,406 7,898 11,176

Seed production (million)

Figure 2.3: PL production (million heads) in the Mekong Delta, 1999-2005

Table 2.7: Number of hatcheries and PL (million) in the Mekong Delta, 2005

Suburban provinces

sea

Number of camps	%	Production of animals alike	%
Long An	1	0.08	6	0.05
Tien Giang	11	0.87	100	0.89
Ben Tre	54	4.28	420	3.76
Tra Vinh	130	10.31	1,000	8.95
Soc Trang	8	0.63	50	0.45
Bac Lieu	112	8.88	3,000	26.84
Ca Mau	905	71.77	6,000	53.69
Kien Giang	40	3.17	600	5.37
Total	1,261	100	11,176	100

(Source: BTS, 2006)

Seed yield

7000

6000

5000

4000

3000

2000

1000

Seed quantity (million)

Among the provinces in the Mekong Delta, Ca Mau province has the largest number of hatcheries (905 hatcheries, 71.77% of shrimp seed production in the Mekong Delta), producing 6,000 million seeds (53.69%), followed by Bac Lieu (26.84%) and Tra Vinh (8.95%) (BTS, 2006) (Figure 2.4).









Long An	Tien Giang	Ben Tre	Tra Vinh		Soc Trang	Bac Lieu	Ca Mau		Kien Giang
Seed yield	g 6	100	420	1,000		50	3,000	6,000		600

Figure 2.4: PL output produced in the Mekong Delta provinces, 2005

2.2. Brackish water shrimp disease situation in the Mekong Delta provinces

Besides the benefits of shrimp farming, the risks are also quite large, such as the pandemic in 1994-1996 in our country, which caused significant damage to farmers. According to Le Xuan Sinh (2003), the number of profitable shrimp farming households accounted for 85.3% (1993), but by 1994 it was only 38.4% and by 2002 the number of shrimp farming households with losses accounted for 25%-30%. Shrimp diseases began to occur at the end of 1993, leading to a decrease in shrimp export output. In 1994-1999, only 20-30% of shrimp farming households were successful (Vo Thi Thanh Loc, 2003).

In 2001, the Mekong Delta faced three shrimp disease outbreaks, mainly in areas shifting from agricultural activities to marine shrimp farming. The first outbreak was from February to March, with about 60% of the shrimp farming area infected, of which Ca Mau was the province with the most damage (about 80% of the shrimp farming area), followed by Bac Lieu with 70% and Kien Giang with 40%. The second outbreak was from July to September, with most of the shrimp farming area in Bac Lieu, Soc Trang with 98% and Kien Giang with 35%. The third outbreak was in October, with 95% of the shrimp farming area in Ngoc Hien district, Ca Mau province (BTS, 2003).

In 2002, most shrimp farming provinces had shrimp infected with disease such as Ben Tre, Tien Giang, Soc Trang and Kien Giang, shrimp were infected after 30-60 days of release. In mid-March 2002, 193,271 hectares of shrimp were infected with disease (BTS, 2003).

Farmed shrimp are infected with white spot syndrome virus (WSSV) and stunting virus (MBV). In Ngoc Hien, Ca Mau, 100% of farmed shrimp are infected with white spot syndrome virus; in My Xuyen, Soc Trang, 50%. About 30.76% of imported shrimp in the Mekong Delta are infected. Some other diseases that cause diseases in shrimp in the Mekong Delta are Vibrio spp ., black gills and poisoning by Mycrocystic, Ceratium, Dinophysis and Psymmesium algae due to ineffective water quality management (BTS, 2003). According to Dang Thi Hoang Oanh et al . (2004), research on shrimp samples showed that from 2001 to 2003, the natural infection rate of WSSV was 13.1% and MBV was 13.8%. The infection rate of WSSV fluctuated according to the sampling months, with the highest in February (37.7%) and November (28.0%). MBV fluctuated less. Shrimp larvae collected from the South Central provinces had higher rates of WSSV (12.5%) and MBV (34.9%) infection than those from the Southwestern provinces.

In 2006, Soc Trang had 3,825 hectares of diseased shrimp farming, accounting for 8% of the province's total farming area (BTS, 2006). According to Tran Van Viet (2006), white spot disease and red body disease are the two main causes of difficulties for farmers. Shrimp farming often gets sick 1 to 3 months after stocking.

According to BTS (2003), the main causes of diseases in farmed shrimp in the Mekong Delta are:

(i) Pond construction does not meet technical standards, design is not suitable.

(ii) Farmers' technical level is low and they lack experience.

(iii) Lack of good quality water sources for water exchange, no settling ponds and wastewater treatment ponds.

(iv) The source of high-quality shrimp seeds is not enough to meet the farming movement and the quality is not strictly controlled.

(v) Shrimp are infected with diseases from other crustaceans outside the pond and farm.

(vi) Some households use homemade feed or low-quality feed, which has worsened the water quality in the pond.

(vii) The farming season is not suitable.

Disadvantages for the development of marine shrimp farming (BTS, 2006):

(i) Planning for the development of marine shrimp farming has not met actual needs.

(ii) Irrigation systems, water supply and drainage systems have not been planned specifically for aquaculture.

(iii) There are no specific regulations on the treatment of wastewater and infected shrimp ponds.

(iv) Loan policies and land use rights are not suitable for marine shrimp farming.

(v) There is no effective system for providing seeds, feed and controlling seed quality.

(vi) Most of the breeding farms have low technology and investment, so it is very difficult to produce disease-free breeding animals.

(vii) Management and planning are still subjective and do not closely follow the actual needs of shrimp farmers.

2.3. Shrimp-rice rotation model

In recent years, the shrimp-rice rotation farming model has had certain developments in farming area and stocking density. In 1999, the shrimp-rice farming area was 36,000 ha, increasing to 117,983 ha in 2001 (Thieu Lu, 2001). The average stocking density increased from 2.2 shrimp/m 2 (1999) to 5 shrimp/m 2 (2001) (Do Quang Tuyen Vuong et al. , 2001). The species stocked is P. monodon.

From 1997-1999, the area of rice cultivation in the rainy season in the shrimp-rice model tended to decrease, due to high profits from shrimp farming, and increased salt content in the soil environment due to the longer dry season (Lu, 2001). According to KTS (2004), the stocking density

The shrimp-rice model has a seed density of 2-3 shrimp/m2 . The survival rate is 10-33%, and the yield is 300-450 kg/ha. The profit from this model ranges from 20-30 million VND/ha with a B/C ratio of 2.5-3 (Table 2.8). The shrimp-rice rotation model is a sustainable production system if one rice crop and one shrimp crop are grown, the shrimp stocking density is low, and the water is changed regularly. Currently, in Soc Trang, there is a trend to increase the shrimp stocking density.

Table 2.8: Technical and economic characteristics of the shrimp-rice model in the Mekong Delta

Value Interpretation

Area (ha) 1-2

Area of ditch covering 25 - 30%

Water depth on the field surface 30 – 50 cm

Artificial Breeding (PL 15 )

Stocking density 2-5 fish/m 2

Breeding season: From February to May

Management of homemade and industrial feed supplements

Survival rate 10-33%

Yield (kg/ha/crop) 300-450

Total cost (C) (million VND/ha/crop) 10-15

Revenue (million VND/ha/crop) 30-45

Profit (B) (million VND/ha/crop) 20-30

B/C ratio 2.5-3

Source: KTS, 2004

2.4. Semi-intensive and intensive farming models

According to Duong Tri Dung (2006), in Dong Hai District, Bac Lieu Province, shrimp farmers have 3-5 years of experience in shrimp farming. Shrimp farmers will not make a profit if the disease cycle occurs less than 2 years/time.

The average total farming area is 20,673m 2 , the average pond size is 0.46 ha. The average stocking density is from 13-30 PL/m 2 . Farmers use industrial feed. The survival rate ranges from 22-44 %. The productivity ranges from 0.5-3.4 tons/ha (KTS, 2004, Duong Tri Dung, 2006 and Tran Van Viet, 2006). The average profit in 2004 was from 43.63-56.05 million/ha/crop for semi-intensive farming models and intensive farming was 66.03-94.34 million VND/ha/crop. Shrimp are stocked 2 crops/year. Crop

Crop 1 from February to August, crop 2 from August to December. The average stocking density in crop 1 is 21.3 PL/m 2 , crop 2 is 13.2 PL/m 2 . The average survival rate in crop 1 is 38.4%, higher than crop 2 at 27.1% (KTS, 2004 and Tran Van Viet, 2006).

According to Tran Van Viet (2006), in Soc Trang and Bac Lieu, about 64% of shrimp farming households lost capital in crop 2 and 49% of households lost capital in crop 1. In addition, the cost of drugs and chemicals also accounts for a high proportion in the cost structure.

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