Slippery Business

Scientists race to understand the reproductive biology of freshwater eels.

eels
©iStockphoto.com/Giuseppe Lancia

The first time I tried to grip a freshwater eel was during an interview with a North Carolina eel dealer, who reached into a concrete-lined pool in his warehouse and tossed one of his captives to the floor in a quick movement. “Pick it up,” he said, with a slightly nasty smile and a challenge in his voice. He nodded his head toward the eel, an adult a yard long and as thick as a baseball bat. It was already making good time squirming across the concrete floor, looking unnervingly like a big snake. Still, I knew that eels are fish and that they don’t have much of a bite, and the task sounded easy enough, so I stooped to scoop the eel off the floor, putting both hands around its body and squeezing. It was like trying to hold a handful of water. In a flash, it slid through my fingers back to the floor, leaving a smear of slime drying on my hands.

Then the dealer showed me the trick. It’s no secret; it was aptly described in an anonymously authored book called Athletic Sports for Boys: A Repository of Graceful Recreations for Youth, published in 1866 in New York. The book included eel fishing as one of those graceful recreations for American boys, and taught them how to handle their catch: “Place the second finger on one side of him, and the first and third on the other, about an inch and a half from his neck. Then by pressing the fingers together he cannot move.” It works.

The idea of an afternoon spent fishing for and handling eels has long since fallen out of favor in the United States. Likewise, eels themselves have disappeared from North American cuisine, where for a long time they held a high place. A handful of eel dealers still buy eels on the U.S. east coast for sale to Europe and Asia, but a significant North American market no longer exists.

Even though people around the world have been eating freshwater eels, and researchers (beginning with Aristotle) have been studying them, for thousands of years, much about the animals remains unknown. Spurred by global population declines, however, scientists are beginning to unlock some of the freshwater eels’ millennial mysteries. And they are closing in on the long-standing goal of breeding eels and raising them to adulthood in captivity on a commercial scale, in hopes of freeing the aquaculture industry from the need to gather young eels from the wild.

More than 700 species of true eels, in the order Anguilliformes, have been identified around the world. Fourteen families of exclusively marine eels include morays and congers; one family of freshwater eels, the Anguillidae, consists of sixteen species, all in the genus Anguilla. Among them, the American eel (A. rostrata), European eel (A. anguilla), Japanese eel (A. japonica), and Australian or shortfin eel (A. australis) have each sustained humans for thousands of years. Paleolithic cave dwellers in what are now France and Spain left European eel bones in their trash middens. Australian aborigines and Native Americans consumed their local species, as did the Greeks. “Fear death,” wrote the Greek comic poet Philetaerus in the fourth century B.C., “for when you’re dead, you cannot then eat eels.”

Members of the Anguillidae are catadromous: they are born and die in salt water, but mainly pass their lives in fresh, a life cycle opposite that of salmon and other anadromous fishes. Every ordinary-looking eel resting in the mud of a North American or European lake, pond, river, or creek has made an astonishing journey from its birthplace in the depths of the Atlantic Ocean’s Sargasso Sea—an approximately two-million-square-mile zone between Bermuda and the Azores. The Sargasso is bounded by strong clockwise currents, which carry the thin, leaf-shaped eel larvae, called “leptocephali,” hundreds or thousands of miles northwest to North America and then northeast to Europe. The two species, American and European, are distinguished by the number of their vertebrae, as well as genetically. American eel larvae also grow faster; they’re ready to hop off the ocean current and head for shore in a year or less, whereas the European larvae continue to go and grow with the flow, possibly for as long as three years.

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