The Life Cycle of Eels

Wildlife biologist Guy Verreault describes the different stages in the metamorphosis of eels during their life cycle.

A close-up view of Guy Verreault appears on the screen. He is facing the camera and gestures with his hands from time to time as he speaks.

[Guy Verreault] Eel is an absolutely fascinating fish from several points of view. It’s essential to understand that eels aren’t born here. They simply pass through here. They’re born in the ocean, somewhere in the Sargasso Sea.

Photograph of an eel larva or leptocephalus.

Eels begin their lives in the form of eggs and then change into leptocephalae. At that stage, they look like a transparent leaf. They then undergo a second transformation.

Photograph of a glass eel.

After this second transformation, they have the shape of an eel, but are transparent. They are known as glass eels because they really look like they are made of glass.

A close-up view of Guy Verreault reappears on the screen.

They’re transparent. Glass eels settle in the mouths of streams and rivers, where they eventually become elvers. They then migrate along these waterways and settle in lakes or stretches of river, where they become what are known as yellow eels. This is simply because the colour of their abdomen turns yellow. It takes another 10, 15, 20 and sometimes even 30 years for them to become silver eels.

Mature silver eel lying on shingles.

In other words, the yellow colouring disappears. The eels turn silver on their abdomen and very dark in colour on their back. This is because, for a fish that migrates in the ocean [A close-up view of Guy Verreault reappears on the screen.], this is the colouring they need to reduce their chances of being preyed on. So they’re called silver eels. When they pass through here, they’re silver in colour.