What If Gone

Species → European Eel

European Eel

Anguilla anguilla

Glass eel recruitment in the North Sea index area was just 0.5% of…
Extinction risk Critically Endangered
MigrationCatastrophic declineWaterwayOverfishing
European Eel (Anguilla anguilla)
Photo: mr_capgras, Wikimedia Commons (CC BY 4.0)

What if it disappeared?

Impact High
Over 40 years

Recruitment of glass eels (young eels arriving at the coast) in the North Sea index area was down to just 0.5% of its 1960-1979 level by 2020 — a 99.5% collapse over four decades, which led to the species being listed under CITES Appendix II and classified as critically endangered.

Documented
Detail

OSPAR Commission (2020). Status Assessment — European Eel.

The decline spans the entire European continent, driven by the combined effect of dams blocking migration, overfishing of glass eels for aquaculture and consumption, introduced parasites, and climate change affecting the ocean currents larvae rely on. Recruitment has stabilized since 2010, but at a level so low that no recovery is yet measurable.

99 years after the hypothesis

By satellite-tracking 26 female eels, a study directly confirmed for the first time that they do reach the Sargasso Sea to spawn — validating, nearly a century later, the hypothesis put forward in 1923 by Danish biologist Johannes Schmidt based solely on larval observations.

Documented
Detail

Wright, R.M., Piper, A.T., Aarestrup, K. et al. (2022). First direct evidence of adult European eels migrating to their breeding place in the Sargasso Sea. Scientific Reports, 12, 15362.

The 26 tracked eels traveled between 272 and 2,275 km in a straight line, at an average speed of 6.8 km per day, over periods of 40 to 366 days — but only five actually reached the Sargasso Sea boundaries before tracking ended, one of them all the way to the presumed spawning zone itself. An honest rather than definitive result: direct confirmation remains partial, five journeys out of twenty-six, even though it is enough to validate the route in principle. Actual spawning has still never been directly observed in wild European eels.

Documentation

Last verified: August 14, 2026