To raise white leg shrimp effectively

(Baonghean) - Since 2008, white-leg shrimp has been chosen by farmers as the main crop to replace black tiger shrimp in brackish water areas of coastal localities. Up to now, the farming area has exceeded 1,300 hectares/crop. However, in recent years, diseases have continuously occurred, affecting productivity and quality, causing many shrimp farmers to suffer.

In the last days of July, we followed the agricultural extension officers to Dien Trung, a commune with a fairly developed shrimp farming industry in Dien Chau district. Mr. Ho Si Kiem, an experienced shrimp farmer here, said: His family has 3 hectares of shrimp farming. In the first crop this year, he released 3 million shrimp fry, not including the cost of feed and shrimp fry, which cost nearly 400 million VND. So far, the first crop has been harvested with positive results, and his family is renovating the pond to prepare for the second crop. However, the whole commune has 45 hectares of shrimp farming, only 6-7 hectares are profitable, accounting for about 15%. This figure for the 2014 crop was about 80%. According to Mr. Kiem, this year, in addition to the prolonged hot weather and higher than average annual temperatures, the main reason is the shrimp fry. Among his 8 ponds, 1 pond has not been affected by any disease. But after 3 months of farming, the shrimp reached 170 shrimp/kg. In other years, with the same farming time, the shrimp reached 50 shrimp/kg. Besides the breed, another reason, according to Mr. Kiem, is that the farming area has been polluted, leading to shrimp getting sick and growing slowly.

Harvesting shrimp crop 1 in Quynh Dy ward (Hoang Mai town).

Quynh Bang is a locality with a strong shrimp farming movement in Quynh Luu district. Shrimp has changed the lives of many farming households here in recent years. The value of shrimp accounts for 40% of the total production value of the whole commune. The whole commune has more than 186 hectares of shrimp farming, with an annual output of 900 - 1,000 tons. The first crop of shrimp this year only reached 320 tons (crop 1 is the main crop of the year). This is the lowest shrimp crop ever, causing many farming households to face many difficulties. Mr. Vu Van Duong, Vice Chairman of the Commune People's Committee, said. Due to the failure of the first crop, more than 90% of the pond area has been renovated by the people to prepare for the second crop of shrimp in the hope of compensating for the loss of the first crop.

According to statistics from the Department of Aquaculture, the area of ​​​​seeding in the first crop in the whole province is more than 1,350 hectares. So far, the harvest has been basically completed with a total output of more than 1,350 tons. Compared to the shrimp farming output in 2014 of 6,000 tons, of which the shrimp output of the first crop accounted for about 3,500 tons. Thereby, it shows that the shrimp output of the first crop this year is low, less than half of the output of the previous year.

In addition to weather factors, one of the main reasons for the failure of this year's farming season is the source of seeds. Although the Veterinary Department has set out very strict regulations on the management of imported seeds in the area, such as imported seeds must be quarantined and must be properly raised. However, due to the lack of control over the source of parent shrimp, the quality of the seed source is not guaranteed. Although when brought back for quarantine, they are disease-free, when raised, the shrimp do not grow large and are often infected with diseases. On the other hand, due to cheap prices, some farmers still buy shrimp seeds floating on the market, of unknown origin. In raising shrimp seeds, 50% of the success of the farming season is determined. On the other hand, due to high frequency of exploitation, each farming area is not thoroughly treated, leading to the emergence of diseases in shrimp.

In 2013, early mortality syndrome was typical, in 2014 it was common for hepatopancreatic disease, and in 2015 most farmed shrimp had intestinal disease. This proves that the shrimp farming environment is increasingly polluted. According to the manager's calculation, the area in the Mai Giang river basin is the province's key shrimp farming area. The annual output is about 4,000 tons. In theory, to get 1 kg of shrimp, 1.1 - 1.3 kg of feed is needed, after conversion, the river basin flowing through the shrimp farming area discharges thousands of tons of shrimp waste every year. This is also the water source for farming areas, so the ponds when taking water are seriously polluted.

Due to the lack of regulations and sanctions to handle violations by households in the farming area, indiscriminate discharge of waste has led to widespread disease spread. According to an agricultural extension officer who specializes in monitoring aquatic products in the farming area of ​​Hoang Mai Town, since the beginning of the farming season, there have been households releasing shrimp seeds up to 4 times. After each release, when shrimp have an incurable disease, they release it into the environment to renovate the pond for another batch. Each discharge is a time when pathogens are spread in the environment, affecting the farming area. Although in some farming areas, community groups have been formed, management is lax, along with no sanctions, so farmers still discharge waste indiscriminately.

Another cause of disease outbreaks in shrimp is that in pursuit of profit, shrimp farmers follow technical farming processes without settling ponds to treat water. According to regulations, the farming pond area accounts for only 70%, the remaining 30% is settling ponds to store and treat water before supplying it to the farming pond. According to Mr. Ho Duc Toan, Dong Van hamlet, Quynh Bang commune (Quynh Luu), this is a professional shrimp farming area but there are still about 50 - 60% of shrimp farming households without settling ponds. This figure in Dien Trung is about more than 30%. On the other hand, farming density also has a significant impact on productivity. According to recommendations, the density of industrial shrimp farming ranges from 70-100 shrimp/m2, but there are households raising more than 200 shrimp/m2. Due to high farming density, when the shrimp develop, it will be impossible to control the disease.

For shrimp farming to develop sustainably, it is necessary to first tighten the management of seed with active measures. According to the feedback of shrimp farmers, in 2013, the seed of CP Company, in 2014, the shrimp seed was favorable, and in 2015, the seed of Viet Uc Company was infected with disease, causing great losses to farmers. These are reputable seed production units, because the seed is not produced locally, the parent seed cannot be controlled, leading to the above situation. From the success of some seed production facilities in the area, industries and localities need to study mechanisms to encourage the development of on-site seed production.

For farmers, cooperative shrimp farming communities have been formed for a long time, but these organizations have not been effective because they have not yet proposed management measures and sanctions to limit households from polluting the environment. Build and form farming areas according to GAP standards to manage the environment. Currently, 7 farming areas according to GAP standards have been built. To ensure safe farming, some farming households have applied the method of resting ponds. Mr. Hoa Duc in Quynh Xuan commune (Quynh Luu) has 12 hectares of shrimp farming, in the first crop he releases 5 hectares of shrimp, in the second crop he releases 7 hectares. The remaining area is rotated to make settling ponds. According to calculations by professional agencies, a plan to "hang up ponds" to clean up the farming environment is also being considered. Mr. Ho Si Tai in hamlet 12, one of the households that won big in shrimp farming in the first crop of this year in Dien Trung commune, shared his experience: This year, he released 270,000 shrimp on an area of ​​2,200m2. After 21 days, he transferred it to another pond of nearly 1,000m2. The results were the same in both large shrimp ponds. The 1,000m2 pond had 40 shrimp/kg, and the 2,200m2 pond had 60 shrimp/kg. These are valuable experiences that shrimp farmers can apply to bring high efficiency.

Article and photos:Mr. Tuan