安尼線蟲科圓蟲寄生於真鰺影響因素之探討

Abstract

真鰺(Trachurus japonicus)為台灣漁業經濟魚種之一。首先本研究目的將探討查明真鰺體內之內寄生蟲相；其次，將真鰺之生理因子包括：真鰺尾叉長、肝臟指數(HSI)、生殖腺指數(GSI)、胃滿率指數(ISF)，並利用統計方法分析其相互影響關係。此外，進一步利用PCR-RFLP 分析Anisakis及Hysterothylacium 屬之蟲種，了解其族群組成情形。 本研究之真鰺從宜蘭大溪漁港取得共480 尾樣本，採樣期間為2005年1 月∼2006 年4 月，寄生蟲相組成以安尼線蟲科(Anisakidae)圓蟲為主，分別為海獸胃線蟲(Anisakis simplex)、有鉤宮脂腺蟲(Hysterothylacium aduncum) 、帶魚針蛔線蟲(Raphidascaris trichiuri) 及前盲囊線蟲 (Pseudoterranova decipiens)；除此之外，尚發現3 種腹殖吸蟲及1 種絛蟲幼蟲。安尼線蟲科圓蟲感染月份大多集中於2∼7 月，豐富度以有鉤宮脂線蟲為最多，其次為海獸胃線蟲。真鰺體長和4 種安尼線蟲科圓蟲總合及海獸胃線蟲之豐富度呈顯著差異(p＜0.01)。GSI 和4 種安尼線蟲科圓蟲總合、海獸胃線蟲及有鉤宮脂線蟲之豐富度呈顯著差異(p＜0.05)。HSI 和海獸胃線蟲之豐富度呈顯著差異(p＜0.01)。ISF 和安尼線蟲科圓蟲之感染豐富度則無顯著差異(p＞0.05)。 Anisakis 屬之RFLP 分析發現台灣東北岸真鰺體內之Anisakis 屬分佈比例為：A. typica 佔60%，recombinant genotypes 佔30%，A. pegreffii 佔10%。Hysterothylacium 屬之RFLP 分析後此屬線蟲只有一種(H. aduncum)並無其它姊妹種。

The horse mackerel, Trachurus japonicus, is one of the important fish species of fishery industries in Taiwan. The aim of this study is to investigate its parasitic fauna firstly. Secondly, physiological factors of horse mackerel including Fork Length, Hepasomatic Index, Gonosomatic Index, and Index of Stomach Fullness are calculated. The possible influencing effects of these factors were finally tested against the infection status in these fish. Furthermore, the infracommunity of two genera Anisakis and Hysterothylacium populations inside horse mackerel was highlighted using polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP). A total number of 480 individuals of horse mackerel were collected from January, 2005 to April, 2006 in Dasi Fishery Harbor of Yilan County. The main parasite fauna includes Anisakis simplex, Hysterothylacium aduncum, Raphidascaris trichiuri, and Pseudoterranova decipiens belonging to the family Anisakidae. Three digeneans and one cestode were also recorded. The main infection months for family Anisakidae nematodes are from February to July, 2005. The highest abundance appears in the infection of H. aduncum, and A. simplex is in the next place. Significant difference between horse mackerel fork length between total numbers of 4 anisakid species were observed, and also did the abundance of A. simplex (p＜0.01). Significant differences between GSI and the abundances of total 4 anisakids, A. simplex, and H. aduncum were noticed (p＜0.05). In addition, difference between HSI with the abundance of A. simplex was significant (p＜0.01). There was no significant difference between ISF and abundance of the 4-species anisakids, A. simplex or H. aduncum (p＞0.05). The infracommuity of the Anisakis populations inside horse mackerel analysed by PCR-RFLP was composed of 60% of A. typical, 30% of recombinant genotype of A. pegreffii and A. simplex s.s., and 10% of A. pegreffii. The result of RFLP analysis showed only one species, H. adundum, in Hysterothylacium populations.