1 Int. Revue ges. Hydrobiol. I 75 1 1990 I 6 I 861 1 R. LECOMTE-FINIGER~ and A. YAHYAOUI~ i Fitcult6 des sciences, Dbpartement de biologie, B.P. 1014, Rabat Maroc, and 2 Laboratoire de biologie marine, Universit6 de Perpignan, 66025 Perpignan cbdex, France Otolith Microstructure Analysis in the Knowledge of the Early Life History of the European Eel, Anguillu anguilla key words: Anguilln anguilln, Leptocephalus, glass eel, otolith, microstructure, early marine life The otolith microstructure of Leptocephalus and glass eel have been analyzed using S.E.M. Thin concentric daily rings were counted in order to follow the different steps of early marine life. The sagitta was translucent, laterally conipressed oval structure with a dark opaque core in the center. A first ring (7.5pn in diameter) delimited this core and could be considered as the hatch check. A second heavy dark ring, 15pm from the center, marked outwards the onset of the daily ring deposition and could be related to the firfit nutritional intake. A diffuse zone located 67 to 110 pin from the center, was probably built up at the nieta- iriorphosis from Leptocephalus to glass eel. It was followed by a thin daily ring deposition which ended in a double ring which showed the transition between marine and continental lives. The total number of the daily rings from the core to the edge was 160 to 225. It revealed that the eel larva spent much less than 3 years in the Atlantic, Ocean as previously believed. The present growth rate was in accordance with hydrological data, particulary the velocity of Northern Atlantic currents.

Otolith Microstructure Analysis in the Knowledge of the Early Life History of the European Eel, Anguilla anguilla

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Page 1: Otolith Microstructure Analysis in the Knowledge of the Early Life History of the European Eel, Anguilla anguilla

1 Int . Revue ges. Hydrobiol. I 75 1 1990 I 6 I 861 1

R. LECOMTE-FINIGER~ and A. YAHYAOUI~

i Fitcult6 des sciences, Dbpartement de biologie, B.P. 1014, Rabat Maroc, and 2 Laboratoire de biologie marine, Universit6 de Perpignan, 66025 Perpignan cbdex, France

Otolith Microstructure Analysis in the Knowledge of the Early Life History of the European Eel, Anguillu anguilla

key words: Anguilln anguilln, Leptocephalus, glass eel, otolith, microstructure, early marine life

The otolith microstructure of Leptocephalus and glass eel have been analyzed using S.E.M. Thin concentric daily rings were counted in order to follow the different steps of early marine life.

The sagitta was translucent, laterally conipressed oval structure with a dark opaque core in the center.

A first ring ( 7 . 5 p n in diameter) delimited this core and could be considered as the hatch check.

A second heavy dark ring, 15pm from the center, marked outwards the onset of the daily ring deposition and could be related to the firfit nutritional intake. A diffuse zone located 67 to 110 pin from the center, was probably built up at the nieta- iriorphosis from Leptocephalus to glass eel. It was followed by a thin daily ring deposition which ended in a double ring which showed the transition between marine and continental lives. The total number of the daily rings from the core to the edge was 160 to 225. It revealed that the eel larva spent much less than 3 years in the Atlantic, Ocean as previously believed. The present growth rate was in accordance with hydrological data, particulary the velocity of Northern Atlantic currents.