Slippery Business

Scientists race to understand the reproductive biology of freshwater eels.

eels on grill

Chefs work the grills at the annual eel festival in Comacchio, Italy. Eel is popular among Europeans, but has fallen out of favor with Americans.

Richard Schweid

Eels may be on the verge of disappearing from tables everywhere. Japanese, European, and American eels share an alarming reduction in the numbers both of elvers navigating upriver and of adults returning downriver. (Eels are far more easily monitored in freshwater than at sea.) In the mid-1990s, the number of elvers in Japan fell precipitously. Although they have since recovered somewhat, they haven’t returned to former levels, and adult-eel catches have steadily declined. The number of elvers entering European rivers is estimated to have fallen more than 95 percent over the past decade, and authorities have declared the European eel population to be “outside of safe biological limits.” As for American eels, Canadian researchers voiced concern about them as early as the mid-1990s, and their numbers have continued to dwindle. In 1982, a daily mean of more than 25,000 eels used an eel ladder at a dam on the upper Saint Lawrence River, in Cornwall, Ontario. By 2005, that number was down to around 200.

The easy part is counting them. The hard part is figuring out why their numbers are declining. Adverse conditions could be affecting the eel at any of the phases in its wide-ranging and uncharted life cycle. Researchers have proposed various causes: habitat destruction in the form of dams and other barriers to upstream migration; disease or parasites; freshwater pollution; climate change, affecting the water temperature or the ocean currents that carry the leptocephali landward; or any combination thereof. Alternatively, the diminishing numbers of elvers and eels could simply reflect a natural cycle that will reverse itself in time.

Europe has reacted in a stronger fashion than Japan, the U.S., or Canada. New restrictions on the capture and trade of adult and glass eels go into force in the EU during 2009. Some member nations have even temporarily banned eel fishing outright. And this past March, listing of the European eel under Appendix II of the Convention on International Trade in Endangered Species of Wild Flora and Fauna (a.k.a. CITES) took effect, placing additional substantive restrictions on the fishery. In Japan, fishing for adult eels is unrestricted but insignificant; the capture of glass eels and elvers for aquaculture purposes is generally prohibited, with some local exceptions.

For its part, Canada has listed the American eel as a “species of special concern,” but not as threatened or endangered. Its capture is legal in all of its home provinces except Ontario. And after a two-year review, the U.S. Fish and Wildlife Service (USFWS) likewise concluded that the American eel is not an endangered or threatened species. So most of the states it lives in continue to permit the harvest of eels longer than six inches, or past the glass-eel stage. “The American eel has experienced declines due to various causes in parts of its range, but we looked closely at the situation and there are millions and millions of them out there,” says David Perkins, a fisheries manager with the USFWS’s Northeast Region who participated in the review. “The species is not in danger of disappearing.”

Still, it’s probably a good thing that Americans have all but stopped eating eel, or their numbers would undoubtedly be lower. Even though most Americans may never lay eyes on an eel—alive or butterflied—the nation would be a poorer place without them. Eels have coexisted with humans for millennia. Their life of transformations makes our own cradle-to-grave journey in the same aging body seem monotonous. The eel is one of those animals that inspires enduring wonder in people who study it. “I used to work with cod, and when I switched to eels I was surprised by the passionate feelings that surround them,” says David Righton of the Eeliad project. “Now I understand it. They are truly marvelous creatures. In Europe, they have not been very fundable and are only now beginning to receive the attention they should have had a long time ago. We’ll see if it’s soon enough.”


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