SPAWNING EELS

摘要

Aristotle thought they came from earthworms. Others thought they spontaneously generated. To this day, no one really knows where eels are made. Yet there are eels - lots of them. This is the story as currently told: American and European eels swim thousands of kilometres to spawn in the Sargasso Sea, a vast, self-contained gyre of water in the western Atlantic near Bermuda noted for warm, salty water. The newly spawned elvers then wiggle and swim their way back. But this extraordinary mission is a matter entirely of inference, first drawn by Danish researcher Johannes Schmidt after a series of expeditions to the Sargasso a century ago. No adult eels have ever been caught spawning there. Until recently, no adult eel had even been seen en route. "Their migration remains a complete mystery," says Melanie Beguer-Pon of Laval University in Quebec. Yet there must be something to the Sargasso tale, says Hakan Wickstrom of the Institute of Freshwater Research in Drottningholm, Sweden."They must spawn there because the tiniest eel larvae are found there," he says.