The seaward migration of European silver eel Anguilla anguilla (L.) was studied during the late freshwater and early marine phase in River Gudenaa and Randers Fjord, Denmark, in the spring 2004. Migration was monitored in sections with different physical characteristics over a total distance of 46 km using automatic listening stations. Generally, eels quickly left the River Gudenaa (67% within 2 days) and stayed for up to 4.3...