Epidemiological studies on viral disease of small abalone(haliotis diversicolor) in northern Taiwan

• Main Authors: Ching-Lung Hsu, 許進隆
• Other Authors: Pen-Heng Chang
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/29106969106607327601

碩士 === 國立臺灣海洋大學 === 環境生物與漁業科學學系 === 92 === Abastract Small abalone (Haliotis diversicolor) is one of the most important shellfish cultured in Taiwan. An outbreak of massive mortality of abalone occurred in northern Taiwan, in January 2003. The epidemic was stroke again in the following year and devastated aquaculture businesses in that area. Herpes-like virus has demonstrated to be associated with the mortality of abalone in the epidemic. In the outbreak, adult and seedling abalone were all attacked and killed. Incubation period of this disease was short. Once death of abalone was found in a pond, all the others will be died in 2 to 7 days. It was an acute, contagious, and highly fatal disease. And prominent gas bubble production in the surface of diseased ponds were noted. The dying abalone showed contraction and dark of abdominal foot. Dead abalone laid its shell upside down at the bottom of pond and its muscle had stains attached. Histopathologic examination revealed necrosis accompanied with few blood cell infiltrations in nerve tissues of infected abalone. Tissue of infected abalone was grinded and centrifuged. The suprenatant was filtered to collect the precipate and examined with electronic microscopy. Herpes-like virus particles, icosahedral in shape, about 100 nm in size were found. Ultra-thin section has demonstrated the virus particles in nucleus of nervous cells and its size and shape were identical to those found in negative staining. In infection test, abalones were injected and bathed. The mortality was 100% in both treatments. The pathological changes of the abalone were identical to those of field cases. In epidemic investigation, several marine fish consisted of haliotis discus, trichus sacelles rotus, and siganus canaliculatus were intact in disesased ponds, but coastal wild abalones were all died during the outbreak. This virus stroke the abalone from the winter of 2003 to the following spring, at the time, the water temperature was between 16℃ to 20℃. The epidemic was found in northern Taiwan only but not spread to other culture areas. Possible sources of contagion included transportation of virus-infected abalone, gears of personnel, equipments for culture practice, reusage of plastic baskets, and virus-polluted seawater.