Elvers

Elvers are juvenile eels that have migrated from the sea into rivers, estuaries, or brackish waters to grow. The term is commonly used for young Anguilla eels during the transition from the transparent glass eel stage to the pigmented juvenile stage that will become yellow eels. Elvers are small, typically a few centimeters long, and they begin adapting to freshwater environments as they progress toward maturity.

Life cycle context: Eels begin life as eggs in the Sargasso Sea, hatch into leptocephalus larvae, and drift in ocean currents. They metamorphose into glass eels, then migrate into freshwater as elvers. In freshwater they grow into yellow eels and eventually return to the sea as silver eels to spawn.

Species and distribution: The elver concept is most closely associated with the European eel (Anguilla anguilla) and the American eel (Anguilla rostrata). Similar migratory juvenile stages occur in other eel species. Elvers are common in temperate river systems of Europe and North America, with populations varying by region and year.

Fisheries and conservation: Elvers are harvested commercially in several regions, sometimes at high rates that have contributed to declines in eel populations. Conservation measures include quotas, seasonal restrictions, and habitat restoration, as well as efforts to improve river connectivity to facilitate migration.

Ecology and behavior: Eels are migratory and nocturnal, with juveniles often seeking shelter among substrate and vegetation in estuaries and lower rivers as they acclimate to freshwater. Their tolerance for salinity allows them to traverse brackish environments during the transitional elver stage.