International eel symposium, 2003 - Quebec August 11, 2003
Poster Session

Reproductive Strategy among Five Subpopulations of American Eel in the St. Lawrence Watershed

Tremblay, V.* Département de Biologie, Université du Québec à Rimouski, 300, Allée des Ursulines, Rimouski, Qc, Canada G5L 3A1, valerie.tremblay@fapaq.gouv.qc.ca

Presenter email address: valerie.tremblay AT fapaq.gouv.qc.ca

Abstract Text: Recruitment of the American eel (Anguilla rostrata) is declining in the St. Lawrence watershed, where the sex ratio is unbalanced in favour of females. As a semelparous species, this demographic dominance enhances its implication on the reproductive potential of the species. Thirty specimens of five different subpopulations were collected at sites ranging from 2845 to 4288 km from the Sargasso Sea. The sustained hypothesis is that fecundity varies among subpopulations; the subpopulation furthest from the Sargasso Sea is expected to show the lowest fecundity at a specific size and the greatest somatic fat stores whereas the nearest subpopulation should show the opposite reproductive strategy. The evaluation of individual fecundity (gonadosomatic index, egg counts) and the analysis of morphological (weight, size, otolith ageing) and physiological (total lipids) parameters on mature migrating female eels should demonstrate that subpopulation fecundity is correlated negatively to its migration distance. The migration distance should influence the trade-off between reproductive and somatic investments among subpopulations and reproductive fitness. Owing to panmixia, no genetic influence is expected to explain the variability in the reproductive traits among subpopulations. Migration distance and environmental parameters might determine life acquisition and allocation of resources. Results are discussed in a management perspective.