Scientists Shed Light on Fate of Endangered European Eel

The European eel has always been a popular fish in Europe--especially when it's smoked, fried or boiled. Despite its popularity in cuisine, though, surprisingly little is known about its life cycle. Now, scientists may have learned a bit more about this eel, which could help with conservation efforts.

European eels spend most of their lives in fresh and coastal waters. Yet the spawning and birth of larvae takes place in the Sargasso Sea in the central Atlantic Ocean. That's located about 4,500 km away from European coastlines, which makes this event difficult to observe. That's why researchers turned to ocean currents in order to learn a bit more about these eels.

The researchers employed an ocean model that was originally used to simulate the effects of melting Greenland glaciers on the North Atlantic. The model has a resolution that's approximately ten times larger than the conventional ocean and climate models.

The scientists ran the model simulation for 45 years. In each of these years, the researchers seeded the Sargasso Sea with eight million tiny drifting particles.

"They represent the eel larvae which, for the first few years of their life, mainly drift with the currents," said Christophe Eizaguirre, one of the researchers, in a news release. "We were able to track how the larvae migrated to Europe. Only those who reached the European shelf seas within two years were considered viable. This also corresponds to eel life cycle."

In the end, the researchers found that eel recruitment in the model fluctuated significantly. In fact, it mimicked the patterns reported across Europe. They discovered that small-scale, wind-driven ocean currents strongly determine the eel population fluctuation. Depending on the presence of regional currents in the Sargasso Sea, the larvae's path to Europe was either extended and led to low recruitment or shortened leading to high recruitment in Europe.

The scientists then combined these discoveries with genetic analyses. This showed them that eels do not return to random locations in the Sargasso Sea to reproduce, as previously thought. Instead, the eels return to where their mother spawned.

The findings reveal a bit more about eel behavior. This could allow researchers to better conserve eel populations in the future, especially as fishing pressures and habitat destruction mount.

"Today, the European eel is on the list of endangered species and biologists, managers, fishers and politicians across the continent are working together to conserve eels and the valuable fisheries they support," said Miguel Baltazar-Soares, one of the researchers, in a news release.

The findings are published in the journal Current Biology.