Extreme swimming: The oceanic migrations of anguillids

Anguillids evolved between 20 and 40 million years ago and, as catadromous fish, migrate between marine and freshwater environments. The migration occurs only twice in the lifetime of most eels: when they migrate as larvae to coastal and river habitats, and again as adult, when they return to their natal habitat to spawn.

In temperate species, the migrations are extreme, requiring larvae and adults to swim thousands of km before reaching their destination, but the migrations of tropical species (hundreds of km) are still remarkable in comparison with many other fish species. To achieve these migratory feats, eel larvae and adults are uniquely adapted to oceanic environments.

We describe and discuss these adaptations, and identify the challenges and opportunities ahead for aquaculture and eel conservation