|
Vol. 47 No. 6, 2008
The Swimbladder Parasite Anguillicola crassus in Native Japanese Eels and Exotic American Eels in Taiwan
Yu-San Han1,*, Ya-Ting Chang1, Horst Taraschewski2, Su-Ling Chang3, Che-Chun Chen4, and Wann-Nian Tzeng1
1Institute of Fisheries Sciences, College of Life Science, National Taiwan University, Taipei 106, Taiwan
2Zoological Institute, Ökologie/Parasitologie, University of Karlsruhe, Karlsruhe 76131, Germany
3Tungkang Biotechnology Research Center, Fisheries Research Institute, Council of Agriculture, Pingdong 928, Taiwan
4Department of Aquatic Biosciences, National Chiayi University, Chiayi 600, Taiwan
Yu-San Han, Ya-Ting Chang, Horst Taraschewski, Su-Ling Chang, Che-Chun Chen, and Wann-Nian Tzeng (2008) To
understand differences in infection patterns of the swimbladder
parasite Anguillicola crassus between habitats and eel species in
Taiwan, the prevalence and intensity of the parasite were examined
based on specimens collected from wild and cultured Japanese eel
Anguilla japonica and from exotic cultured American eel A. rostrata in the Kaoping River and culture ponds in southwestern Taiwan in 2006-2007. The prevalence of Aco. crassus
in wild Japanese eels was lower in winter compared with summer/autumn,
varying 33%-58%, with a mean intensity of 1.5-4.4. The prevalence
and intensity were sizedependent and increased with eel size. In
cultured Japanese eels, the prevalence and mean intensity varied
greatly at 3%-68% and 1.0-29.0, respectively. In cultured
American eels, the prevalence and intensity were very high in ponds
without drug treatment. In contrast to wild eels, the mean
intensity of larval and adult worms showed a size-dependent decreasing
trend in cultured eels. The mean body mass of Aco. crassus
in American eels was significantly larger than that in Japanese
eels. The external morphology, condition factor, and
hepatosomatic index showed no significant differences between infected
and uninfected groups, indicating a low pathogenic effect of Aco. crassus
on these 2 eel hosts. Our results showed that both native
Japanese eels and naive American eels are highly susceptible to Aco. crassus, but it causes little pathogenicity under good pond management.
Key words: Anguillicola crassus, Anguilla japonica, Anguilla rostrata, Infection, Aquaculture.
*Correspondence: Tel: 886-2-33663726. E-mail:yshan@ntu.edu.tw
|
