Biological Measures or Paired Shrimp Disease Prevention Mainstreaming Measures

For the prevention and control of prawn disease this year and later, Professor He Jianguo, chief scientist of the Chinese shrimp industry system, believes that the biological control model for polyculture of Penaeus vannamei and other fish may become the mainstream measure for the prevention and treatment of shrimp disease in the future.

In the first half of last year, shrimp culture in South China suffered from the most serious diseases in the past 20 years, and large areas of ponds have emerged in major fish farming areas. However, there are many opinions about the main causes of diseases, such as seedlings, new viruses, vibrio, spores, and the environment. However, there has been no clear conclusion that the haze of diseases has been lingering.

A new round of breeding will begin again, and the mood of the farmers to invest in seedlings is not to be overemphasized. How to prevent the recurrence of diseases has become the biggest challenge for the shrimp industry.

On April 8th, at the 3rd China shrimp industry development forum held in Zhanjiang, the prevention and control of shrimp disease became one of the focuses of this forum. For the prevention and control of disease this year and beyond, Professor He Jianguo, chief scientist of the Chinese shrimp industry system, believes that adopting biological control to polyculture Penaeus vannamei and other fish will be the mainstream measure for the prevention and treatment of future shrimp diseases.

The etiology of shrimp is still not clear that the basic symptoms of early disease in shrimp last year showed no feed, empty stomach, jejunum, bloated, etc. He Jianguo preached that last year's shrimp disease presented several facts: First, the occurrence of ponds in April-June was more severe; second, compared with the second-generation seedlings, the incidence rate of imported seedlings was much higher, and the deaths obviously advanced. Thirdly, cyanobacteria and dinoflagellates became dominant species in the culture ponds, especially in shrimp ponds where water was relatively fat, resulting in faster onset and death of shrimp.

In view of the fact that the shrimp disease prevalent in the past year was caused by the virus, Yang Feng, a researcher at the Third Institute of Oceanography of the State Oceanic Administration, admitted that research from its breeding area in Fujian Province found no virus particles at the level of electron microscopy.

In this regard, He Jianguo believes that the disease is related to the environment, including some possible inputs. "So far, we have only found that in a large number of dead shrimp there is a kind of microorganism called "Mycoplasma"." He mentioned that this organism was discovered in 1996 in Penaeus monodon grown in the United States. It could enter cells and destroy cells, resulting in liver atrophy, but He Jianguo believes this is not a major pathogenic factor.

Huang Hailin, a researcher of yellow seawater that has also been working on virus prevention and control, talked in an exchange that when he isolated the samples collected from Beihai, Guangxi, two bacteria were isolated, one of which was Vibrio parahaemolyticus. In general, Vibrio will not cause a disease as large as last year." Huang Ye believes that there is no evidence that the disease last year was caused by a problem.

In this regard, Yang Feng also agree. “A lot of diseases have similar symptoms. Sometimes it is difficult to distinguish. For example, the results of our tests on multiple farms show that it is caused by white spot disease. However, white spot disease has a very weak lethal ability, and it has a large area of ​​death last year. The situation does not match."

He reminded first-line breeders that disease prevention and control in this year's disease prevention should be sampled and analyzed in a timely manner (sampling with live shrimp). If you take dead shrimp as a sample, the microorganisms in the body may already have a large number of bacteria, which will bring many problems to disease identification. Certainty. Because, "toxins that are released during the growth of various algae may also cause the death of shrimp."

In terms of sporozoite-induced diseases, He Jianguo also analyzed that "sporeworms require intermediate host parasites and it is difficult to find intermediate hosts in pond culture. This argument is difficult to establish."

Biological control to reduce the spread of disease Although the cause of shrimp is not yet clear, He Jianguo believes that in the prevention and control of shrimp diseases this year and later, the use of biological control to polyculture or other species of white prawn and other fish is a kind of Effective measures, he analyzed the current experiments, "One of the ways to spread shrimp diseases is to feed live shrimp on dead shrimps, and a white-spot syndrome virus carried by a 7-cm shrimp will infect 52 fish. It can eat sick shrimp and reduce the infection rate."

The fish and shrimp polyculture model can also improve feed utilization on the other hand. Li Jian, deputy director of the Yellow Sea Fisheries Research Institute, also mentioned the benefits of polyculture in multi-nutrition farming. “Shrimp and fish are different in feeding and they feed on bite feeds in the swimming. Once the feed particles are broken, dissolution will cause A lot of food is wasted, and polyculture fish can make full use of bait."

On the forum, Mr. Ban Bundi, the chairman of the Indonesian Shrimp Products Committee, introduced the experience of the shrimp industry in Indonesia. He said that due to the influence of IMNV (Infectious Muscle Necrosis Virus) in Indonesia in previous years, The shrimp production continues to decline, but ultimately relying on the polyculture of fish and shrimp to effectively control the shrimp disease.

In addition, He Jianguo reminded, “The fish mixed with shrimp need to choose the right variety, and can't choose to eat with the shrimp, and the beard bream is a good mixed fish; in addition, it is inferior to some shrimps in terms of oxygen tolerance. Fish can also be used in small quantities as an indicator organism for the state of dissolved oxygen in the pond; some fish farmers breed some shellfish in shrimp farming, but shellfish actually do not have biological control.”