Methods for identifying aquaculture diseases

Aquaculture, particularly intensive or super-intensive high-density breeding, can lead to disease outbreaks in fish and shrimp due to microbial infection. One notorious disease is acute hepatopancreatic necrosis disease (AHPND) or early mortality syndrome (EMS), caused by Vibrio parahaemolyticus, a bacteria that can infect tiger prawns, white shrimp, and Chinese prawns. AHPND causes the hepatopancreas cells to collapse and malabsorb, leading to immobility or circling swimming, anorexia, slow growth, and soft shell in diseased shrimp. It is estimated that AHPND causes approximately US$1 billion in losses each year in aquaculture.

To identify the causative agent of disease, such as V. parahaemolyticus, nucleic acid can be extracted from shrimp tissues, particularly the gut and hepatopancreas, and amplified using polymerase chain reaction (PCR) for rapid identification. However, proper dissection and tissue collection are crucial for accurate analysis.

In summary, the intensification of aquaculture can lead to disease outbreaks, with AHPND being a significant cause of losses in shrimp culture. The use of advanced biotechnology, such as PCR, allows for rapid identification of the causative agent, but proper tissue collection is crucial for accurate analysis.

Review questions:

• What is acute hepatopancreatic necrosis disease (AHPND) or early mortality syndrome (EMS), and what is its economic impact on aquaculture?
• How can nucleic acid be extracted from shrimp tissues, and what is the importance of proper tissue collection for accurate analysis?
• What are some of the causes of disease outbreaks in fish and shrimp in aquaculture, and how can they be prevented?