|
Vol. 49 No. 5, 2010
Comparison of Recapture Rates and Estimates of Fishing and
Natural Mortality Rates of Japanese Eel Anguilla japonica between Different
Origins and Marking Methods in a Mark-Recapture Experiment in the
Kaoping River, Southern Taiwan
Yu-Jia
Lin1, Su-Lean Chang2, Mei-Yu Chang1,
Shih-Huan Lin1, Tzyy-Ing
Chen2, Mao-Sen Su2,
WeiCheng Su3, and
Wann-Nian Tzeng1,*
1Institute
of Fisheries Science, College of Life Science, National Taiwan
University, Taipei 106, Taiwan
2Division of Biotechnology, Fisheries Research
Institute, Pingtung 928, Taiwan
3Fisheries Research Institute, Keelung 202, Taiwan
Yu-Jia Lin, Su-Lean
Chang, Mei-Yu Chang, Shih-Huan Lin, Tzyy-Ing Chen, Mao-Sen Su, WeiCheng
Su, and Wann-Nian Tzeng (2010) In total, 100 wild Japanese eels marked
by microchips, 146 by pectoral fin clipping, and 100 cultured eels
marked by microchips and 436 by caudal fin clipping were released in
the lower reach of the Kaoping River, southern Taiwan. Recapture rates
of marked wild eels did not significantly differ between individuals
marked by microchips and pectoral fin clipping (p = 0.51), but did differ between
cultured eels marked by microchips and caudal fin clipping (p = 0.01). For wild and
cultured eels marked by microchips, cultured eels had a significantly
higher recapture rate than wild eels (p
< 0.001), and eel length at release did not affect the recapture
rates (p = 0.38).
According to the Akaike information criterion corrected for the sample
size, estimates of fishing and natural mortality rates differed between
pectoral fin clipping and microchips in wild eels. However,
neither rate differed between pectoral fin clipping and microchip in
cultured eels. Both eel origin and marking method might influence
the recapture rate and mortality rate estimates. Different
behaviors of cultured eels in the wild and reaction to the marking
process are possible reasons. Higher mortality rates of wild eels
marked by pectoral fin clipping were unexpected, probably due to a
size-related mortality rate, behavioral changes, or mortality
associated with pectoral fin clipping.
Key words: Japanese
eel, Mark-recapture, Recapture rate, Mortality rates.
*Correspondence: Tel: 886-2-33662887. Fax:
886-2-23639570. E-mail:wnt@ntu.edu.tw
|
