||Japanese eel is an important aquaculture species in East Asia. Because the commercial scale of artificial propagation of the glass eel has not been established yet, the needed elvers are all caught from the wild. This results in a serious bottleneck for the aquaculture industry. It is estimated that the current eel resource in East Asia is less than 10% in comparing to that in year 1970s. Taiwan also suffers the the same impact. The Japanese eel is mainly cultured in Taiwan, China, Korea, and Japan, with mean elvers demand about 100 metric tons annually. In Taiwan, the year demand of the elver is around 10-20 metric tons, far less than the average catch of 4-8 metric tons. Thus, lots of elvers are imported from China and Japan. However, the aquaculture scale has been growing in China since 1990s. The unbalance of supply and demand for the elver would become more and more serious in the near future. Thus, to manage and recover the valuable eel resource is a key for the sustainability of eel aquaculture industry. This projrct will mark and release adult Japanese eel in the Yilan River around spring. The benefit evaluation of the eel stock releasing will be asessed to reach the goals of increasing the eel resource and benefiting fishermen. The six goals of the project are:
1. To perform eel stock releasing program in Yilan River.
2. To investigate the growth of the released eels in the river.
3. To investigate the gonadal development of the released eels in the river.
4. To study the migratory dynamics of the released eels in the river.
5. To promote the concept of eel conservation.
6. To raise a suitable strategy for eel resource management.
The predicted benefits of this project are:
1. To understand the current resource of the wild eel in Taiwan, including species composition, sex ratio, age and growth, and maturation.
2. To understand the growth, silvering, and gonadal development of the released eels for evaluation of its maturation.
3. To understand the spawning migration of the released eels by comparing with that of wild silver eels.
4. To increase the elver stocks and benefit fishermen after successful releasing program.