European eel found to spawn across 2000 km wide region of the North Atlantic Ocean

A team of researchers with members from Japan, Sweden, Denmark and Germany has found evidence showing that European eel spawn across a 2000 km wide region of the North Atlantic Ocean. In their paper published in the journal Biology Letters, the group describes their study of recently hatched eel larvae in the North Atlantic Ocean, and what they found.

Almost a hundred years ago, scientists discovered that European eels have a unique lifestyle—one that includes spawning in the Sargasso Sea, which is approximately 5000 to 7000 kilometers from where they live as juveniles and adults in European and North African rivers. But the extent of their spawning has never been pinned down. The researchers note also that the number of European eels has been dropping dramatically since the 1970s, and nobody knows why. The current population is believed to be approximately 5 percent of what it once was. In this new effort, the researchers used multiple ships to survey large parts of the North Atlantic Ocean from approximately 70°W to 50°W—to learn more about the spawning habits of the endangered eel.

The Sargasso Sea is actually an area entirely within the North Atlantic Ocean, just off the east coast of the United States—it is the only sea in the world that has no land boundaries. It became singled out as voyagers discovered it was bounded by four ocean currents that form a gyre. It was named for the Sargassum seaweed that grows in abundance there. Prior research has shown the area to be mostly free of geographical formations—its bottom is mostly flat. The area is known for its marine plants and for its deep blue hue.

The researchers report that their survey efforts showed recently hatched eel larvae floating across a 2000 km-wide region of the North Atlantic Ocean—not just the Sargasso Sea. They noted also that prior researchers working as far back as 1921 had found the larvae in similar parts of the ocean. The researchers suggest that despite severe reductions in population, the European eel still spawns as far and wide as it ever did. They suggest also that their findings may contribute to a plan for preventing the eels from disappearing altogether.