九孔幼苗大量死亡原因之探討

Abstract

台灣鮑 (Haliotis diversicolor supertexta) 俗稱九孔或珍鮑魚,除了實 用與用價值外。同時亦具外銷潛力與競爭力,並成為我國輸出養殖水產品 主力之一。自2001年起,宜蘭縣地區的九孔苗陸續發生大量脫落死亡現象, 造成業者莫大損失,至今從北蔓延到高雄縣及台東縣,而澎湖亦有相似病 例發生。而於2003年1月下旬,在台北縣貢寮地區九孔養殖場,包括潮間帶 養殖池和陸上養殖池,陸續都有死亡情形。類似之病情,曾發生在大陸在 1999到2000年冬春季節,福建省東山、漳浦養殖九孔鮑魚爆發的大量死亡。 九孔幼苗發生脫落現象不只發生在台灣,自1999年起在中國大陸沿海,南 至海南島也陸續發生種苗大量脫落現象。由此可見,病害的發生是全面 性,而且可能是某一因素所造成。本實驗室曾就九孔苗部分進行病原分離 和病理學檢查。在病理學檢查及電子顯微鏡的觀察下發現Rickettisa-like organism。相較於同屬不同種的紅鮑及黑鮑魚感染Rickettisa-like organism,會因為溫度及食物來源與Rickettisa-like organism多寡造成紅鮑 魚及黑鮑魚的衰弱及死亡。因此,目前的結果尚無法確定Rickettisa-like organism是造成九孔幼苗大量死亡之原因。

The species of abalone cultured in Taiwan is belong to genus Haliotis, family Haliotidae, and locally known as “nine hole” and “pearl abalone”. It’s not only used to be traditional herb, but also be one of the important exported goods in Taiwan’s aquiculture industry. The die-off of nursery abalone was first occurred in Yielan in 2001 and the farmers suffering severe econimic loss. The situation of nursery abalone die-off has spreaded out to Kaohsiung, Taitung and Penhu. High mortality of adult abalone occurred in north eastern Taiwan in January 2003. The abalone fishery in Dongshan and Zhangpu in Fujian province also had similar mortality of adult abalone during 1999 winter to 2000 spring. This situation quickly spread out along the Mainland China coast from Shangdong province to Hainan Island. In the study, Rickettisa-like organism has been found in adult abalone using hitopathology exam and transmissible electronmicroscopy. The Rickettisales-like organism, which cause withering syndrome is found in black abalone (Haliotis cracherodii) and red abalone (H. rufescens). There mortality of balck abalone maybe related to rickettisales-like organism intensity, temperature, and food supply. Results in the study are unable to clarify the relationship between rickettsiales-like organism and nursery abalone die-off.