Before their fall migration, adult eels undergo changes that adapt them for life in the ocean. These changes include an accumulation of fat and the degeneration of the gut. Spawning migration takes place between August and December, with eels being most active at night. American eels spawn in the western Sargasso Sea between January and March. A female eel may lay between 400,000 and 2,500,000 eggs.
Parents die after spawning.
The eggs hatch and the young, which look like transparent ribbons, are seized by ocean currents and transported to the mouth of the Chesapeake Bay and other inlets of the Atlantic Ocean. This journey can take months or even years. After their first year, the young change, taking on the form of tiny, unpigmented eels, known as glass eels. Glass eels become pigmented as they move to coastal areas. Their bodies turn dark brown and their metamorphosis is complete.