A German-led team of scientists has completed a sixth round of research in a spawning area of the Sargasso Sea for the critically endangered European eel.

Led by Reinhold Hanel, a professor of the Thünen Institute of Fisheries Ecology in Germany, the team departed St George’s on the Walther Herwig III on March 17 with 36 people on board — 24 seafarers and 12 scientists — for the expedition, which ran until April 12.

Mr Hanel has been working with his team in the Sargasso Sea region for more than a decade, a government spokesman said.

His first research expedition to the area was in 2011, when scientists set out from Bermuda to investigate the spawning grounds of European eels.

Following the most recent trip, Mr Hanel said: “Many aspects of the eels’ spawning behaviour and early development remain unknown, including the exact locations and environmental conditions of spawning.

“During the recent expedition, researchers collected plankton samples across a large survey area in the western and central Sargasso Sea to determine the distribution, abundance and size of eel larvae.

“These data are essential for understanding recruitment processes and long-term population trends of this critically endangered species.

“The work also contributes to broader ecosystem research as, in addition to eel larvae, the scientists are studying plankton communities including jellyfish, sunfish larvae and mesopelagic fishes that inhabit the so-called ‘twilight zone’ of the ocean.”

David Freestone, the executive secretary of the Sargasso Sea Commission, said a single species action plan for the European eel was agreed at the fifteenth Conference of the Parties of the Convention on Migratory Species this month.

He added: “This plan has been in the making for years, with the Sargasso Sea Commission facilitating meetings of the range states of the European eel.

“Data from researchers like Professor Hanel was instrumental in getting it over the finish line.”

The Sargasso Sea is the only spawning area for the European eel which carries the scientific name Anguilla anguilla.

The eels spawn in the ocean to the south of Bermuda but migrate several thousand kilometres to inshore Europe, the Baltic, the Mediterranean and northern Africa, to live most of their lives in brackish or freshwater environments.

They are harvested for human consumption, driving a decline that is exacerbated by other threats, including habitat loss, barriers to migration and pollution.

The eel population has experienced a decline of more than 90 per cent since the 1970s.

As Bermuda is the only landmass in the Sargasso Sea, the spokesman said the Government has championed the conservation of the globally significant and unique ecosystem for more than a decade.