International Commemorative Symposium, 70th Anniversary of The Japanese Society of Fisheries Science. 1-5 October 2001. Yokohama, Japan. Disinfection of water for aquaculture is critical for preventing the introduction and spread of infectious disease. A pathogen-free water source is essential for success in aquaculture. Typical treatment systems make use of high efficiency sand filters to clarify the water before treatment with ultraviolet (UV) light or ozonization. Fish pathogens are divided into two groups based on their sensitivity to UV and total residual oxidants (TROs) produced by ozonization of seawater. Hypochlorite produced by electrolysis of seawater (salt water) showed bactericidal and viricidal effects. This method can easily treat large volumes of water, and is suitable for disinfecting wastewater before discharging.
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"In river systems where salmonids migrate, as well as in seawater, most pathogens of importance to salmon farming may be present. The risk may be reduced significantly by employing water disinfection systems; treatment with UV light or ozone are the methods of choice (Kasai et al. 2002). However, no water treatment systems have the capacity to eliminate microorganisms completely, only to reduce the infectious load substantially (Liltved et al. 1995). "
[Show abstract][Hide abstract] ABSTRACT: To avoid fish pathogens, potential ports of entry into hatcheries and farms have to be identified and barriers put in place, e.g., restricted admission; personnel locks; and disinfection of biological material, water supply, and vectors. For Atlantic salmon, the water supply is of greatest potential risk for introduction of pathogens, both during the freshwater and seawater phases. Seawater constitutes the highest risk both to smolt farms and sea sites. Live fish material is also high risk. Among vectors, personnel and fomites coming into contact with infectious material pose the greatest risk, i.e., vaccinators, net cleaners, and wellboats.
"In river systems where salmonids migrate, as well as in seawater, most pathogens of importance to salmon farming may be present. The risk may be reduced significantly by employing water disinfection systems, treatment with UV light or ozone are the methods of choice (Kasai et al. 2002). However, no water treatment systems have the capacity to eliminate microorganisms completely, only to reduce the infectious load substantially (Liltved et al. 1995). "
[Show abstract][Hide abstract] ABSTRACT: Biosecurity plans may be implemented to control one specific infection or to prevent the introduction of infectious agents in general, applying wide-ranging, hygienic principles. However, a biosecurity plan aiming at controlling one specific infection will also protect against the introduction of others, control measures being more or less general. Biosecurity plans may be applied to different community levels or geographical areas, such as continents, countries, regions, zones, compartments and, in aquaculture, to the farm or site level. Vectors include working staff, servicemen, consultants, authority representatives, veterinarians, vaccination personnel, and visitors. Equipment, such as different technical installations, brushes, landing nets, and automatic vaccination machines, can carry pathogens between sites/farms, as well as transport vehicles like cars and vessels, and their cargo. Predators and scavengers (birds and animals) can also
be vectors for fish disease agents. In general, the water supply is considered to constitute the greatest risk for introduction of pathogens to a smolt farm. The risk level varies significantly with type of water source, depending on the fish populations inhabiting the water. However, no water treatment systems have the capacity to eliminate microorganisms completely, only to reduce the infectious load substantially. The biosecurity plan at a fish farm must be based on the particular production system, adjusted to meet the requirements of the technical equipment and water supply of the farm, and to the disease panorama in the region.
"Inactivation effects of UV irradiation, ozonization, and electrolyzation of water were studied against six fish rhabdoviruses; IHNV, HIRRV, pike fry rhabdovirus (PFRV) , spring viremia of carp virus (SVCV), eel virus from America (EVA), and eel virus from Europe X (EVEX) , three fish herpesviruses; OMY, Herpesvirus salmonis (R. salmon is ), and channel cat fish herpesvirus (CCHV), fish birnaviruses; rPNV, fish reovirus; chum salmon virus (CSV), fish iridovirus; Japanese flounder lymphocystis disease virus (JF-LCDV), and fish nodavirus (BF-NNV) (Kasai et ai., 2002). "
[Show abstract][Hide abstract] ABSTRACT: Special Issue: International Symposium on Koi Herpesvirus Disease : Strategy for Koi Herpesvirus Disease Control. 13 March 2004. Yokohama, Japan. Survival of three salmonid viruses and two marine fish viruses in fish rearing water or coastal sea water were observed at 0, 5, 10 and 15 ℃ for 7 or 14 days. Interaction between viruses and microorganisms present in the rearing water was observed. Infectious pancreatic necrosis virus (IPNV) and fish nodavirus (BF-NNV) were stable in waters used at every temperature tested for 14 days, but it was observed that, for infectious hematopoietic necrosis virus (IHNV), Oncorhynchus masou virus (OMV), and hirame rhabdovirus (HIRRV), as the temperature increased, the loss of infectivity also increased. When IHNV and OMV were suspended in filtrated and autoclaved rearing water, infectivity was reduced in comparison with the untreated water. Subsequently, adsorption of IHNV to mud or small particles was studied. IHNV adsorbed to several clays (kaolin, bentonite, Japanese acid clay) and diatomaceous earth in sterilized water with a wide range of pH (5-11) at concentrations of 1, 10, and 100 mg/mL. Except for bentonite, infectivity of clay-adsorbed IHNV persisted for at least 9 weeks. The clay-adsorbed IHNV also persisted in infectivity to rainbow trout Oncorhynchus mykiss, causing cumulative mortality rates of more than 73 %. Then, inactivation effects of UV irradiation, ozonization, and electrolyzation of water were studied against six fish rhabdoviruses, three fish herpesviruses, one fish birnaviruses, one fish iridovirus, and one fish nodavirus. Six rhabdoviruses, three herpesviruses, and lymphocystis disease virus were found to be sensitive to UV irradiation, ozonization, and electrolyzation. Susceptibility of IPNV, chum salmon virus (CSV), and BFNNV to UV was found to be low. IPNV and CSV were low sensitive to ozonization and electrolyzation. Virucidal effects of six kinds of disinfectants were examined against OMV, IPNV, IHNV, and HIRRV at 15 and 20℃ for 30 sec and 20 min. At 15℃ for 20 min, minimum concentrations showing 100 % plaque reduction of viruses tested by iodophore, sodium hypochlorite solution, benzalconium chloride solution, saponated cresole solution, formaldehyde solution, and potassium permanganate solution were 40, 50, 100, 100, 3500, and 16 ppm, respectively.