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 Published and unpublished data from 6 sites (Canada, United States, Sweden, France, Taiwan and Japan) sampled across the geographical range of each eel species were compiled.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.KEY WORDS: Habitat use · Anguilla spp · Otolith Sr:Ca
Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 308: [231][232][233][234][235][236][237][238][239][240][241] 2006 shelf of Europe and North Africa. The American eel A. rostrata also spawns in the Sargasso Sea and travels 2000 to 3000 km into North American waters while the Japanese eel A. japonica spawning area is located west of the Mariana Islands (NW Pacific) and its nursery grounds extend through continental waters of East Asia. Tropical species have shorter migrations (Marui et al. 2001). Leptocephalus larvae metamorphose into glass eels as they arrive at continental shelves (Bertin 1951, Tesch 2003. Glass eels become pigmented elvers as they penetrate estuaries, rivers and streams and complete their growth phase in a large choice of habitats (lagoons, estuaries, marshes, rivers, lakes and streams). The growth phase typically lasts from 3 to 15 yr and is followed by a second metamorphosis into silver eel, a pre-pubertal stage. Silver eels achieve their sexual maturation as they swim back to their spawning grounds (Van den Thillart et al. 2004).Although the presence of yellow eels (juveniles) in brackish and marine waters has long been known, the dominating paradigm has been that eel growth phase was restricted t...
