ABSTRACT
There are 19 species of freshwater eels (Genus Anguilla) in the world, which are all catadromous fi shes, spawning in the open ocean but growing in continental freshwaters, estuaries, and lagoons (Tesch 2003). Freshwater eels are divided into temperate and tropical species. The temperate eels, A. anguilla, A. rostrata, and A. japonica, in the northern hemisphere have declined to less than 10% of their population level in the 1970s in the past 3 decades. The reason for their decline is not clear but might be due to global climate change, overfi shing, and habitat degradation, etc. (e.g., Knights 2003, Tzeng et al. 2012, Chen et al. 2014). Because of their population decline, the catch of temperate glass eels is not enough to meet the demand for aquaculture and thus the tropical glass eels have been used to supplement the temperate glass eels, particularly the Japanese eel, for aquaculture. To avoid the over-exploitation of tropical glass eels for aquaculture, both the Philippine and Indonesian governments have prohibited the export of tropical glass eels to Asian countries for aquaculture. For sustainable eel aquaculture industry and eel resources conservation, we need to understand the fi shery status, the population decline, and why the eel couldn’t recover its population size by self-regulation? The eel has been proposed to be able to adjust its sex ratio to maximize population level
1 Institute of Fisheries Science, National Taiwan University, Taipei 10617, Taiwan. 2 Department of Environmental Biology and Fisheries Science, National Taiwan Ocean University,
Keelung 20224, Taiwan. E-mail: wnt@ntu.edu.tw
(Colombo and Rossi 1978). Over-exploitation of the temperate eel resources may have reduced the eel population to a level too low to recover (Quinn and Deriso 1999). This chapter mainly reviews the biology and fi shery of the Japanese eel in Taiwan to examine possible conservation methods for the eel.
