THEY are slimy, look like snakes and live under rocks. They bite. No wonder eels are unloved. But 25,000 people are employed in the eel fishing industry in Europe alone. And eels fascinate biologists, who have never discovered exactly where they breed. Their secret may soon be safe forever, for it seems the eel could be about to disappear.
Willem Dekker of the Netherlands Institute for Fisheries Research in Ijmuiden says that the population of European eels (Anguilla anguilla) is now just 1 per cent of what it was in 1980. Its American cousins (Anguilla rostrata) are doing little better. 鈥淭here are almost no eels left in the Great Lakes,鈥� Dekker told New Scientist. The recent stock estimates were presented last week at the annual scientific meeting of the International Council for Exploration of the Seas in Tallinn, Estonia.
Eels from Europe and North America migrate to an unknown spot in the Sargasso Sea to spawn and die. This began millions of years ago, when the Atlantic was a narrow strait. As plate tectonics pulled Europe and America apart the trip has become ever longer, with larvae relying on the Gulf Stream to drift home. The two species evolved from a common ancestor when fast-developing individuals metamorphosed and headed inland while passing North America, while the late bloomers reached Europe.
Advertisement
In estuaries the larvae become tiny, transparent glass eels. They change into yellow elvers as they head upriver, maturing as silvery adults decades later. But that journey is no longer possible for most of the fish. 鈥淚n Spain and Portugal, where the eel population is densest, dams have closed 90 per cent of the rivers to eels,鈥� says Dekker. It鈥檚 a similar story in other countries. Building fish ladders would help the eels past dams, he says, but few dam owners bother.
Meanwhile, glass eels are sold as a delicacy, or passed to eel farmers in China and Japan. No one has bred eels in captivity, so wild eels are their only source. The few that make it upstream are taken by small freshwater fisheries, says Dekker. 鈥淚n the Ijsselmeer in the Netherlands only 1 female in 700 escapes鈥�.
Other pressures are also taking their toll. The oily fish accumulate PCBs and other persistent toxins, while many European eels are now infected with an Australian parasite that arrived in live eels imported from Japan.
鈥淲e warned governments in 1997 that they had to control the fishery,鈥� says Dekker. 鈥淭hey did absolutely nothing.鈥� If they act now, there may still be a chance, he says. 鈥淚f not, we will lose the eel.鈥�