One of nature’s most mystifying questions has been where European eels spawn and their journey to that mysterious location. Earlier this month, a team of researchers with the United Kingdom’s Environment Agency published a study with critical information about the final segment of their migration.
The European eel is considered critically endangered, as the number of eels that return from their mysterious spawning grounds has declined by 95% in the past 40 years. The eels spawn in the Sargasso Sea, which sits off the coast of the eastern United States in the Atlantic Ocean. No land surrounds it, and the Sargasso Sea is instead flanked by four currents that create an oceanic whirlpool (a gyre) where sargassum algae aggregate.
The eels’ journey to the Sargasso Sea is over 6,000 miles in length and to understand what that path looks like, British scientists along with collaborators from Denmark and the Azores affixed satellite tags to 26 female eels and released them from the Azores archipelago (where the eels have been tracked to thus far). Data from 23 of those transmitters showed that the eels do travel towards the Sargasso Sea over the course of a whole year.
Since humans started tracking their journey in the 4th century B.C., it has only ever been suggested through indirect evidence that the Sargasso Sea is the eels’ likely spawning ground.
According to Matthew Gollock, Chair of the Anguillid Eel Specialist Group for the International Union for Conservation of Nature, “Populations of the European eel are at a historic low and the more we understand their life-history, the better we are able to develop conservation measures to address the critical status of the species.”
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