Tactics and demographic attributes in the European eel Anguilla anguilla in the Gironde watershed, SW France

• Main Authors: Daverat, Françoise, Tomas, Javier
• Other Authors: Ecosystèmes estuariens et poissons migrateurs amphihalins (UR EPBX), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), Institut Mediterrani d'Estudis Avancats (IMEDEA), Consejo Superior de Investigaciones Científicas Madrid (CSIC)-Universidad de las Islas Baleares (UIB)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2006
• Subjects: GIRONDE ESTUAIRE; MIGRATION CATADROME; ESTUAIRE; HABITAT; OTOLITHE; ANGUILLA ANGUILLA; [SDE]Environmental Sciences; Canada; Anguilla anguilla; European eel
• Online Access: https://hal.archives-ouvertes.fr/hal-00684426; https://hal.archives-ouvertes.fr/hal-00684426/document; https://hal.archives-ouvertes.fr/hal-00684426/file/BX2006-PUB00019151.pdf

Habitat use patterns of 3 species of temperate eels, Anguilla anguilla, A. japonica and A. rostrata, were investigated using otolith strontium:calcium ratio life history transects. Published and unpublished data from 6 sites (Canada, United States, Sweden, France, Taiwan and Japan) sampled across the geographical range of each eel species were compiled. Sr:Ca patterns indicated that the 3 species displayed similar patterns of habitat use. In all sites, patterns of habitat use consisted of either residency in one habitat (fresh, brackish, or marine) or movements between habitats. One movement pattern consisted of either a single change or 2 changes of habitat from fresh to brackish waters, or from brackish water to freshwater. Seasonal movements between fresh and brackish waters were observed for all 3 species. When only a single habitat switch event was detected, it occurred between 3 and 5 yr of age. Occurrence of eels with no freshwater experience was demonstrated, but such eels accounted for a smaller proportion of the overall sample than eels with some (even brief) freshwater experience. Contrary to the common convention that these are obligate catadromous species, we must now consider them as facultative catadromous, with far more flexibility in habitat use. The most variable parameter among study sites was the relative proportion, rather than the diversity, of lifetime spent in the various habitat use patterns. Eels found at higher latitudes exhibited a greater probability of remaining in the lower reaches of watersheds in brackish water. Diversity of habitat use appears to be a common strategy of temperate eel species, and, as a life history tactic, is under environmental control.