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Marine Ecology Progress Series

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MEPS 272:231-244 (2004)  -  doi:10.3354/meps272231

Variation in the annual growth, by sex and migration history, of silver American eels Anguilla rostrata

B. M. Jessop1,*, J. C. Shiao2, Y. Iizuka3, W. N. Tzeng4

1Department of Fisheries and Oceans, Bedford Institute of Oceanography, PO Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada
2Institute of Zoology, and
3Institute of Earth Sciences, Academia Sinica, Nankang, Taipei, Taiwan 11529, ROC
4Institute of Fisheries Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan 10617, ROC

ABSTRACT: Silver American eels Anguilla rostrata from the East River, Chester, on the Atlantic coast of Nova Scotia, as evaluated by the temporal pattern of Sr:Ca ratios in their otoliths, showed variable patterns of migration between river and estuarine/marine waters during their yellow eel stage. Eels with a history of primarily estuarine residence were longer (total length) at migration and had higher annual growth rates than did eels with a primarily freshwater residence. Female eels were longer at migration and had higher annual growth rates than did males. The percentage (64%) of silver eels with a history of estuarine residence and their larger size at age, size at migration, and higher growth rate relative to freshwater resident eels may result from higher productivity in oceanic than freshwaters at higher latitudes, as modified by regional environmental conditions. Environmental conditions change with increasing latitude in a different pattern for American and Japanese eels than for European eels.

KEY WORDS: Anguilla rostrata · American eel · Otolith microchemistry · Strontium:calcium ratios · Migratory history

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