Do eels go to breed at sea then come back?

Yes, many eel species undertake extensive migrations for breeding. The most famous example of this is the European eel (Anguilla anguilla). Eels are catadromous, which means they live in freshwater but migrate to the ocean to spawn. Eels spend most of their lives in freshwater rivers and lakes. However, when they reach sexual maturity, they undergo a remarkable transformation and migrate back to the ocean. This migration can cover thousands of kilometers and can take several months or even years to complete.

When eels reach the ocean, they undergo several physiological changes. Their bodies become more streamlined and their fins become larger and more powerful. These changes help them to swim long distances in the open ocean. Eels also undergo a change in coloration, becoming darker in color.

Eels spawn in the Sargasso Sea, an area of the North Atlantic Ocean located east of Bermuda. The exact location of the spawning grounds is not known for sure, but it is believed that eels spawn in very deep water. Eels release millions of eggs and sperm into the water. The eggs hatch into larvae that drift with the ocean currents.

The larvae eventually make their way back to freshwater rivers and lakes. They undergo a metamorphosis and transform into elvers. Elvers are small, transparent eels that live in freshwater for several years. They then grow into adult eels and the cycle begins again.