Early life history and recruitment of the tropical eel Anguilla bicolor pacifica , as revealed by otolith microstructure and microchemistry

Dispersal pattern of glass eel stage of Anguilla australis revealed by otolith growth increments

“…The present study found that the Australiasian eel A. australis took approximately 7 to 9 mo to drift from the spawning grounds to the estuaries of Australia and New Zealand (Table 3), and metamorphosis from leptocephalus to glass eel occurred approximately 5 to 6 mo after hatching. Our estimates of age are similar to those of Arai et al (1999c), who compared the ages of New Zealand glass eels collected at the same estuaries in 1996. This provides independent confirmation of the ageing technique.…”

“…To assess this, we compared our data from Albert River (Site A3) in 1997 with published data from the same sampling site in 1996 (Arai et al 1999c). The mean age of glass eels at metamorphosis and estuarine arrival were 164 ± 18.6 d and 208 ± 17.4 d in the Arai et al (1999c) study and 161 ± 12.6 d and 217 ± 16.6 d in the present study.…”

“…To assess this, we compared our data from Albert River (Site A3) in 1997 with published data from the same sampling site in 1996 (Arai et al 1999c). The mean age of glass eels at metamorphosis and estuarine arrival were 164 ± 18.6 d and 208 ± 17.4 d in the Arai et al (1999c) study and 161 ± 12.6 d and 217 ± 16.6 d in the present study. This very close agreement of ages for different years indicates that interannual variability of age at metamorphosis and recruitment in the same estuary may be minor, and less than variability due to geographic differences.…”

“…The glass eels of Stages VA and VB were believed to be the new recruits in the estuary. Arai et al (1999c) indicated that glass eels kept in freshwater for 10 d after collection develop to Stages VIA1 to VIA4. This suggests that 244 Table 2.…”

“…Arai et al (1999c) recently determined the age of Anguilla australis on a daily basis and found that the glass eels recruited to Australia (208 ± 17.4 d) were ca 20 to 30 d younger than those recruited to New Zealand (232 ± 19.8 d western coast, 237 ± 20.0 d eastern coast). They considered that the difference in age of glass eels arriving at the coasts of Australia and New Zealand might be due to differences in the migratory routes taken by these 2 stocks (Arai et al 1999c), but had insufficient data to determine the actual routes. Comparing the daily age of glass eels at metamorphosis and upon estuarine arrival across their dispersal range is a useful technique to help determine the migratory routes of eel larvae (Cheng & Tzeng 1996, Wang & Tzeng 1998.…”