Responsible shrimp culture through ecological approach

Abstract only.Aquaculture is the fastest food-producing sector. It is the farming of aquatic organisms, like crustaceans, fish, molluscs and plants. Culture of aquatic organisms, particularly shrimps, is usually done in earthen ponds with some intervention in the rearing process to enhance production. Some of these processes to increase production are pond preparation, regular stocking, feeding, and the use of probiotics and other chemicals to improve soil, water quality, shrimp growth and immunity against diseases. The long range effect of the use of probiotics and other chemicals on the environment and on shrimps is unknown. Despite the various inputs, diseases continue to plague the industry, which could be due to the deteriorating environmental conditions that cause stress in shrimps thus making them susceptible to infection. Furthermore, chemicals and nutrients from aquaculture may affect biodiversity of the receiving environment. Responsible aquaculture is a sustainable development approach that meets the needs of the present generation without compromising the ability of future generations to meet their own needs. There should be a good balance between satisfying human needs while maintaining or enhancing the quality of the environment and conserving natural resources. Human health or food safety as well as economic efficiency and/or livelihood opportunities should be taken into consideration. Responsible shrimp culture through ecological approaches to improve environmental conditions is herewith described. Ecological approaches recognize the interactions between an aquaculture farm and the external environment, including environmental resources and local communities. Ecological approaches to improve environmental conditions identified from cross sectional, longitudinal and tank studies may be classified into culture systems and phases of pond production: pond preparation and rearing. Two culture systems are identified to improve water quality: 1) the use of the greenwater system, and 2) the presence of mangrove in the receiving environment. Among the pond preparation practices, sludge removal, crack drying of pond, and liming were identified. Toxic substances as well as organic matter, which provide nutrients necessary for the growth of microorganisms, are removed during sludge removal and crack drying of the pond sediment. Liming to pH 11 kills most harmful microorganisms including the white spot syndrome virus; it also kills unwanted species in the shrimp pond like fish and crabs. During the rearing phase, abundant supply of natural food, low stocking density, less input, addition of fermented Avicennia alba leaves, use of molasses and rest periods are some of the important farming practices that reduce risk of disease occurrence. Other reported practices are crop rotation, biofloc technology, aquaponics, and integrated multi trophic aquaculture

The relation between farming practices, ecosystem, and white spot in syndrome virus (WSSV) disease outbreaks in penaeus monodon farms in the Philippines

The white spot syndrome virus (WSSV) affecting shrimp aquaculture in most producing countries has caused huge economic losses resulting in bankruptcy to both large and small farmers. Studies done on WSSV epidemiology were mostly tank-based and on species other than Penaeus monodon. There is a need to investigate WSSV epidemiology in P. monodon in on-farm situations, thus including both risk and protective factors. This thesis aimed to generate knowledge that can improve prevention against WSSV in shrimp culture through better farm husbandry by studying the epidemiology of WSSV in on-farm situations. To achieve this goal data from cross-sectional and case studies were analysed to identify on-farm WSSV risk and protective factors, and longitudinal studies were done to assess factors affecting water quality and causing WSSV infection to result in an outbreak. The thesis identified the following WSSV risk factors related to the physico-chemical parameters of the water: low and fluctuating temperature, low and fluctuating salinity, and pH fluctuation. The risk of high temperature and high salinity for an outbreak of WSV disease may be related to fluctuations in these two parameters. Risk factors related to farm husbandry techniques were feeding with molluscs, sludge removal and its deposition on the dike, sharing water source with other farms and having the same receiving and intake water. Identified WSSV protective factors were high mangrove to pond area ratio, feeding with natural food or phytoplankton, and higher percentage of beneficial bacteria like the yellow colonies that grow on thiosulphate citrate bilesalt sucrose agar, a Vibrio selective medium. Results of the longitudinal studies demonstrated that WSSV infection may not result in outbreaks in greenwater pond and in ponds with mangroves in the receiving environment. Our results did not provide explanations why the WSSV infection did not result in an outbreak in farms with mangroves in the receiving environment. In greenwater ponds, this was attributed to the better water and soil quality, higher plankton count, and higher heterotrophic bacterial count.</p

Factors affecting mortality of shrimp, Penaeus monodon, experimentally infected with Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (VPAHPND)

One of the most recent diseases affecting the shrimp industry is the early mortality syndrome (EMS). EMS, characterized by observed mortality in shrimp within the first 35 days of culture, is due to several diseases, one of which is the acute hepatopancreatic disease (AHPND). Outbreaks due to AHPND have caused economic losses to many shrimp producing countries globally. This paper investigates factors affecting mortality of shrimp, Penaeus monodon experimentally infected with Vibrio parahaemolyticus causing AHPND (VPAHPND). Tank experiments done suggested that exposure to 107 cfu/ml VPAHPND, 35°C, and 10 and 28 ppt increase the risk of shrimp mortality due to AHPND. The VPAHPND concentration in the water that P. monodon can overcome is AHPND is age related, with higher mortalities in younger infected shrimp.The study was funded by the Government of Japan under the Trust Fund (GoJ TF 6) granted to SEAFDEC/AQD under study code FH04-C2015T. The authors express their gratitude to Ms. Remedios Sobremisana and Mr. Joshua Fabillo for the assistance during conduct of the study

A Nonluminescent and Highly Virulent Vibrio harveyi Strain Is Associated with “Bacterial White Tail Disease” of Litopenaeus vannamei Shrimp

Recurrent outbreaks of a disease in pond-cultured juvenile and subadult Litopenaeus vannamei shrimp in several districts in China remain an important problem in recent years. The disease was characterized by “white tail” and generally accompanied by mass mortalities. Based on data from the microscopical analyses, PCR detection and 16S rRNA sequencing, a new Vibrio harveyi strain (designated as strain HLB0905) was identified as the etiologic pathogen. The bacterial isolation and challenge tests demonstrated that the HLB0905 strain was nonluminescent but highly virulent. It could cause mass mortality in affected shrimp during a short time period with a low dose of infection. Meanwhile, the histopathological and electron microscopical analysis both showed that the HLB0905 strain could cause severe fiber cell damages and striated muscle necrosis by accumulating in the tail muscle of L. vannamei shrimp, which led the affected shrimp to exhibit white or opaque lesions in the tail. The typical sign was closely similar to that caused by infectious myonecrosis (IMN), white tail disease (WTD) or penaeid white tail disease (PWTD). To differentiate from such diseases as with a sign of “white tail” but of non-bacterial origin, the present disease was named as “bacterial white tail disease (BWTD)”. Present study revealed that, just like IMN and WTD, BWTD could also cause mass mortalities in pond-cultured shrimp. These results suggested that some bacterial strains are changing themselves from secondary to primary pathogens by enhancing their virulence in current shrimp aquaculture system

Phage Therapy and Photodynamic Therapy: Low Environmental Impact Approaches to Inactivate Microorganisms in Fish Farming Plants

Owing to the increasing importance of aquaculture to compensate for the progressive worldwide reduction of natural fish and to the fact that several fish farming plants often suffer from heavy financial losses due to the development of infections caused by microbial pathogens, including multidrug resistant bacteria, more environmentally-friendly strategies to control fish infections are urgently needed to make the aquaculture industry more sustainable. The aim of this review is to briefly present the typical fish farming diseases and their threats and discuss the present state of chemotherapy to inactivate microorganisms in fish farming plants as well as to examine the new environmentally friendly approaches to control fish infection namely phage therapy and photodynamic antimicrobial therapy

Disk diffusion method

Disk diffusion method is based on the principle that antibiotic-impregnated disk, placed on agar previously inoculated with the test bacterium, pick-up moisture and the antibiotic diffuse radially outward through the agar medium producing an antibiotic concentration gradient. The concentration of the antibiotic at the edge of the disk is high and gradually diminishes as the distance from the disk increases to a point where it is no longer inhibitory for the organism, which then grows freely. A clear zone or ring is formed around an antibiotic disk after incubation if the agent inhibits bacterial growth.The Government of Japan Trust Fund through SEAFDEC Aquaculture Department provided financial support for the research project and publication of this manual. We would like to express our sincere thanks to Dr. Yasuo Inui and Dr. Kazuya Nagasawa, the former and current Fish Disease Experts and Leaders of the Regional Fish Disease Project, for their encouragement and critical suggestions; and the staff of the Fish Health Section, SEAFDEC Aquaculture Department, for their kind cooperation, especially to Dr. Celia R. Lavilla-Pitogo for carefully reading the manuscript and Dr. Edgar C. Amar for serving as the over-all coordinator in the preparation of drafts. Thanks also to Dr. Hisatsugu Wakabayashi, Emeritus Professor of Fish Pathology Laboratory at the University of Tokyo, for reviewing the manuscript

Laboratory manual of standardized methods for antimicrobial sensitivity tests for bacteria isolated from aquatic animals and environment

The manual is one of the important outputs of a collection of studies related to antibiotic usage in order to come up with guidelines for its prudent usage. It offers a complete guide for testing bacterial susceptibility and resistance through the use of simple techniques for disk agar diffusion tests, and a guide to do a more thorough study to test therapeutic levels using microbial inhibitory concentration.The Government of Japan Trust Fund through SEAFDEC Aquaculture Department provided financial support for the research project and publication of this manual. We would like to express our sincere thanks to Dr. Yasuo Inui and Dr. Kazuya Nagasawa, the former and current Fish Disease Experts and Leaders of the Regional Fish Disease Project, for their encouragement and critical suggestions; and the staff of the Fish Health Section, SEAFDEC Aquaculture Department, for their kind cooperation, especially to Dr. Celia R. Lavilla-Pitogo for carefully reading the manuscript and Dr. Edgar C. Amar for serving as the over-all coordinator in the preparation of drafts. Thanks also to Dr. Hisatsugu Wakabayashi, Emeritus Professor of Fish Pathology Laboratory at the University of Tokyo, for reviewing the manuscript. Bacterial isolation, identification and storage Disk diffusion method Minimal inhibitory concentration (MIC) test and determination of antimicrobial resistant bacteria </ol

Bacterial isolation, identification and storage

Bacterial isolation, purification and identification are the first steps to bacteriological studies. Isolation is done to obtain pure bacterial cultures. Bacteria are usually isolated from fish kidney and spleen; and from the hepatopancreas, lymphoid organ and muscles of shrimp. These tissues are monitor organs that usually harbor the disease-causing bacteria during infection.The Government of Japan Trust Fund through SEAFDEC Aquaculture Department provided financial support for the research project and publication of this manual. We would like to express our sincere thanks to Dr. Yasuo Inui and Dr. Kazuya Nagasawa, the former and current Fish Disease Experts and Leaders of the Regional Fish Disease Project, for their encouragement and critical suggestions; and the staff of the Fish Health Section, SEAFDEC Aquaculture Department, for their kind cooperation, especially to Dr. Celia R. Lavilla-Pitogo for carefully reading the manuscript and Dr. Edgar C. Amar for serving as the over-all coordinator in the preparation of drafts. Thanks also to Dr. Hisatsugu Wakabayashi, Emeritus Professor of Fish Pathology Laboratory at the University of Tokyo, for reviewing the manuscript