Shrimp aquaculture in tropical regions is facing a disease-induced catastrophe of lost production. It is estimated that more than 40% of tropical shrimp production is lost to disease annually. The devastating impacts of disease on lost incomes, livelihoods, increased operational costs, trade restrictions and loss of consumer confidence has been a subject of many consultations and policy dialogues. Discussions of disease crisis have to date been largely focused on identification of pathogens, guidelines and standards for disease detection and surveillance, regulations to limit trans-boundary movement of animals, and adoption of better management practices.
There is reason to believe that current broodstock management practices may induce genetic erosion that increases susceptibility to disease and vulnerability to epizootics:
The basic tenet for this Expert Consultation is that an important aggravating factor in the disease crisis is an agro-economic system that locks shrimp breeders, hatcheries and farmers into behaviour that induces high levels of inbreeding. If inbreeding does increase the severity and frequency of epidemics, this disease crisis will only get worse over vast areas of Asia, Central and South America, Africa and the Middle East until it is addressed.
This Expert Consultation was organized in conjunction with the annual meeting of the NACA Aquatic Animal Health Advisory Group (NACA-AG) to take advantage of the physical presence and expertise of a small group of world renowned Aquatic Animal Health experts from several national and international institutions. The list of participants and workshop agenda are presented in Annexes 1 and 2. This consultation is perhaps the first of its kind to bring together a balanced group of experts from diverse fields – epidemiology, microbiology, disease diagnostics & surveillance, aquaculture genetics, fish breeding, and evolutionary biology – to take a fresh, in-depth, and wider perspective on the possible interaction between genetic side-effects of broodstock management and the looming threat of aquatic animal diseases, in particular the contemporary shrimp disease crisis.
This study focused on events in a representative, 50-pond Indonesian shrimp farming system in Pangkep district, South Sulawesi. Ponds were stocked with Penaeus monodon and the study extended across a single cropping period between May and October 2010. It was designed to improve our understanding of the main causal pathways for white spot disease (WSD), the most serious cause of production loss in these systems. The longitudinal observational study focused on recording the occurrence of different genotypes of the causal infectious agent, white spot syndrome virus (WSSV), in selected components of the system across time, and looking for relationships with pond outcomes, particularly WSD occurrence. We expected that findings would (a) enable relevant Indonesian agencies, and ultimately farmers themselves, to better identify localities suitable for smallholder shrimp farming using better management practice (BMP) programs and (b) inform modification and simplification of these programs, thereby improving both profitability and adoption rates.
Our transmission trials showed that genotypy variations did not occur during three sequential passages (four including the preparation of the stock inoculums) in L. vannamei or alternatively in other crustacean hosts. This indicates the genotypes are likely to be sufficiently stable for use in local epidemiological studies during disease outbreaks in shrimp ponds.
WSD outbreaks were recorded in 11 of the study ponds. Outbreaks were attributed to WSSV genotype TRS5 in seven ponds and to genotypes TRS4 and TRS6 in two ponds each. Data analysis showed that:
These findings suggest that stocking PCR test-negative PLs, coupled with careful management of water intake during nearby WSD outbreaks are the two most useful practice changes farmers can adopt to reduce the risk of outbreaks in their ponds. Establishment of an active, well-resourced and trained extension service, committed to fostering cohesive, informed farmer groups, is the key to enabling these inexpensive practice changes.
NACA is pleased to announce the release of a new flagship publication, Success Stories in Asian Aquaculture. The stories in this book reflect the unique nature of Asian aquaculture, providing first-time insight into how and why it has become so successful. Overall, the book demonstrates how the resiliency, adaptability, and innovation of small-scale aquaculture farmers have been crucial to this success. It also places aquaculture development in Asia into a wider global context, and describes its relationship to natural systems, social conditions, and economics. The book is unique in its in-depth presentation of primary research on Asian aquaculture, and in demonstrating how aquaculture can have a lasting positive impact on livelihoods, food security, and sustainable development.
Aquaculture Successes in Asia: Contributing to Sustained Development and Poverty Alleviation
Sena S. De Silva and F. Brian Davy
Recent Developments in Rice-fish Culture in China: A Holistic Approach for Livelihood Improvement in Rural Areas
Shrimp Farmers in India: Empowering Small-Scale Farmers through a Cluster-Based Approach
N.R. Umesh, A.B. Chandra Mohan, G. Ravibabu, P.A. Padiyar, M.J. Phillips, C.V. Mohan, and B. Vishnu Bhat
Backyard Hatcheries and Small Scale Shrimp and Prawn Farming in Thailand
Hassanai Kongkeo and F. Brian Davy
Cage Fish Culture: An Alternative Livelihood Option for Communities Displaced by Reservoir Impoundment in Kulekhani, Nepal
Tek B. Gurung, Raja M. Mulmi, K.C. Kalyan, G. Wagle, Gagan B. Pradhan, K. Upadhayaya, and Ash K. Rai
Enhancing Rural Farmer Income through Fish Production: Secondary Use of Water Resources in Sri Lanka and Elsewhere
Upali S. Amarasinghe and Thuy T.T. Nguyen
Striped Catfish Aquaculture in Vietnam: A Decade of Unprecedented Development
Nguyen Thanh Phuong and Dang Thi Hoang Oanh
The Genetic Improvement of Farmed Tilapias Project: Impact and Lessons Learned
Belen O. Acosta and Modadugu V. Gupta
The Role of Exotics in Chinese Inland Aquaculture
Jiashou Liu and Zhongjie Li
Synthesis and Lessons Learned
Sena S. De Silva, F. Brian Davy, and Michael J. Phillips
This book will appeal to a wide range of readers. The introduction and conclusion give an excellent general overview of Asian aquaculture, and the individual case studies provide a wealth of new information for specialist readers. Researchers, development workers, and decision-makers, in particular, will be interested in how the Asian experience might be used to strengthen aquaculture development more generally and in other parts of the developing tropics of Latin America and Africa.
Success stories in Asian Aquaculture is edited by by Sena S. De Silva, Director General of the Network of Aquaculture Centres in Asia-Pacific, and F. Brian Davy, Senior Fellow at the International Institute for Sustainable Development in Canada. You can order hard copies of the book online from the Springer website.