The eel belonging to the catadromous species of migratory fish (spawning in the sea) spends most of its life in the river and migrates downstream and into the Sargasso Sea in the Atlantic Ocean south of the Bermuda Islands, where it spawns. After 3 years the eel larvae reach the European coastal waters and become glass eel which often migrate upstream the rivers in great swarms. During several years of life in the rivers they then achieve their full size. Once they are mature (females after 12-15 years) they return to the Sargasso Sea to spawn.
For protection purposes and future management of the endangered eel populations in Europe, the European Union issued a regulation (EC No. 1100/2007) in June 2007 focussing on a restoration of the stocks of eel and on reducing eel mortality of anthropogenic origin. According to this regulation, all EU Member States with natural stocks of eel drafted national Eel Management Plans by end 2008 which they handed over to the EU Commission. They are summarized in the report no. 207 "National Measures according to the EU Eel regulation (EU regulation no. 1100/2007) in the Rhine catchment during 2010-2012".