| Summary: | Habitat use patterns of three species of temperate eels, Anguilla anguilla, A. japonica and A. rostrata were investigated using otolith Sr:Ca life history transects. Published and unpublished data from six sites (Canada, United States, Sweden, France, Taiwan and Japan) sampled across the geographical range of each eel species were compiled.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 three 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 or two changes of habitat from fresh to brackish waters, or from brackish water to fresh water. Seasonal movements between fresh and brackish waters were observed for all three species. When only a single habitat switch event was detected, it occurred between 3 and 5 years of age. Occurrence of eels with no freshwater experience was demonstrated, but such eels accounted for a smaller proportion of the overall sample than did eels with some (even brief) freshwater experience. Contrary to the common convention that these species are obligate catadromous, we must now consider them as facultative, 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.
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