Catadromous Fish spawn in the ocean and migrate to fresh water to grow to adult size such as the American Eel.
American Eel. As adult eels mature, they leave the brackish/freshwater growing areas in the fall (August to November), migrate to the Sargasso Sea and spawn during the winter. The Sargasso Sea is a large area of the western North Atlantic located east of the Bahamas and south of Bermuda. After spawning the adult eel dies. The eggs hatch after several days and develop into a larval stage that drifts through the ocean for several months until they enter the Gulf Stream current to be carried north towards the North American continent. As the larvae approach the continental shelf, the larvae transform into miniature transparent eels called "glass eels". As glass eels leave the open ocean and enter into estuaries they are know as elvers. With each life stage of the eel there is a commercial fishery that impacts not only eel populations but also other species including salmon, alewives, smelt and trout. This migration begins in late winter and continues through the summer months. Eels may stay in growing areas from 8-25 years before migrating back to sea to spawn.