A Plague of Asian Eels Highlights The Damage From Foreign Species

MIRAMAR, Fla. – An aluminum boat carrying federal biologists roars down Canal C-9, a 20-mile-long waterway that passes a stone's throw from Pro Player Stadium, home of the Miami Dolphins.

The boat, which is equipped with an "electro-fishing unit," slows to a stop, and one of the men lowers two chandeliers of thick wires into the water. With the press of a pedal, he unleashes up to 800 volts into the murky depths. The scientists are stalking one of the newest, most indestructible aquatic predators in the U.S.: the Asian swamp eel.

The more scientists learn about the eel, Monopterus albus, the more discouraged they become about stopping it. Here is what is known so far: It has a bottomless appetite for any aquatic life in its path -- fish, frogs, shrimp, crayfish and insects. A nocturnal hunter, it is rarely seen by humans. The three-foot-long adults have no known natural enemies, with the possible exception of alligators.

By Land or by Sea

The eel's most alarming trait, though, is its uncanny ability to survive extreme conditions. In one study by a Harvard zoologist, an Asian swamp eel lived seven months in a damp towel without food or water. The olive-brown creature prefers tropical waters, yet it can flourish in sub-zero temperatures. It prefers fresh water but can tolerate high salinity. It breathes under water like a fish, but can slither across dry land, sometimes in packs of 50 or more, sucking air through a two-holed snout. It breeds year-round, with one eel laying as many as 1,000 eggs at a time. No mates nearby? No problem: Almost magically -- scientists still don't know how -- the eel can change into a female from a male. Even more of a riddle is how to kill the eel: It thus far appears almost immune to poisons and dynamite.

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"We can't find a chink in its armor," says Leo Nico, a biologist with the U.S. Geological Survey, the nation's largest water, earth and biological science agency.

As if this weren't cause enough for concern, the eel is now within a mile of the ecologically fragile Everglades National Park, a 1.5 million-acre oasis of rare plants, animals and fish, and the subtropical jewel of America's park system. If the eels reach the park, there's a chance they could start gobbling their way through one of America's most-threatened ecosystems.

The tale of the eel's discovery in the U.S. offers a window into one of the most vexing problems facing the environment in America today, rivaling wildfires, logging, flooding, earthquakes or tornadoes in sheer economic damage -- the vast and silent explosion of invasive species. In a trend accelerated by the globalization of the world economy, about 50,000 introduced and invasive nonnative species have entered the U.S. to date. Some, such as corn, wheat, rice, cattle and poultry, proved their value to the economy and culture long ago.

But the problems caused by other newer invaders are taking their toll. Introduced and invasive species cost the U.S. an estimated $138 billion annually according to a study last year by four researchers at Cornell University.

In Louisiana, for instance, Formosan termites chew up historic homes in the French quarter of New Orleans and a sheriff's SWAT team shoots beaver-size, nonnative swamp rats from South America overtaking drainage canals. Suppressing a 1996 infestation of Asian long-horned beetles in New York City cost the state and federal governments more than $4 million. In the Great Lakes, Zebra mussels introduced by Russian freighters in 1986 now cause an estimated $5 billion in damage annually to pipes, boats and other structures. Exotic weeds and plants -- a particular nuisance to Western ranchers -- are expanding their range at a rate of 4,600 acres a day.

The environmental cost, meanwhile, is incalculable. Nonindigenous species disrupt delicate food webs and upset rare breeding sites. About 42% of the species listed as endangered or threatened under the Endangered Species Act are there because of competition or predation by foreign species. And there's no end in sight: Every minute, 40,000 gallons of ballast water are dumped into U.S. harbors, some of it containing exotic organisms that could alter or destroy marine ecosystems, according to the Department of Commerce. Even baby's breath, the tiny white flowers from Eurasia that float on a bride's veil, is a menace to unique habitats in the West.

Concerned about the federal and state governments' scattershot and overlapping response to the problem, President Clinton 18 months ago signed an executive order creating the National Invasive Species Council, for the first time coordinating the efforts of 20 federal agencies. In a detailed "management report" to be released next week for public comment, the council outlines ambitious plans to create an early-detection team, educate the public, strengthen import controls and design an online database of species where scientists around the world can share information.

"America's landscape is being transformed by swamp eels, cheatgrass and a host of other creatures and weeds that don't belong," Secretary of the Interior Bruce Babbitt said in a written response to questions. "The national invasive species plan now being proposed is a big, first step in turning back this unwelcome tide."

The Asian swamp eel would still be in hiding today were it not for the abiding curiosity of a Smithsonian Institution scientist named Wayne Starnes, who discovered the eel on the North American continent. Along the way, a hurricane, a part-time snail specialist, a student in Jakarta, and a spontaneous roadside stop by a piranha expert all played a crucial role in understanding what scientists know so far about the species.

In late September 1994, Mr. Starnes, an ichthyologist with a Ph.D. in ecology, flew to Atlanta from his Washington lab for a conference sponsored by the American Zoological Association, where he was eager to pitch a book project on freshwater fish. One evening, on a lark, he joined his co-author, a professional nature photographer named Dick Bryant, in a 20-minute drive north of Atlanta to judge a nature photography contest at the Chatahoochee Nature Center, a log-cabin style museum surrounded by ponds and winding trails. While touring the exhibits at night with a staffer, he noticed a dish on a table that held a three-inch worm as thin "as a thick pencil lead."

"Where did you get this?" he asked the staffer. Earlier in the day, children were collecting bugs and crawfish and "these worms" to study in the center, the man replied. Mr. Starnes lifted the dish to his eyes. It looked like a tiny eel, he said to himself. But American eels wouldn't be this far inland -- they spawn in the ocean. Was it a siren, the eel-shaped salamander with no hind legs, or perhaps a Southern Brook Lamprey, which is native to the Chatahoochee River?

Dr. Starnes slipped the eel in a small vial with formaldehyde and carried it in his briefcase back to the lab at the Smithsonian in Washington. Adjusting the focus of the microscope, Mr. Starnes stared at the eel and whispered to himself, "Oh man, I've seen this face before." It was the same family of eels he had seen on research trips to South America and Central America. This particular family of eels is also found in India, African swamps and flooded rice fields in Asia. The eels had been spotted in Hawaii years ago.

Crash Diet

To further educate himself, Mr. Starnes relied on several early eel studies, including one by a Harvard professor named Karel Liem, whose research reached back to the 1960s. Prof. Liem's own first encounter with the eels was memorable: As a graduate student at the University of Indonesia in Jakarta, he traveled one night in 1961 to a swamp to collect frogs for his thesis project. Suddenly, his headlamp lit up a herd of eels moving across land. Shocked and intrigued, "I collected 87 live specimens in maybe less than an hour," he said. He's studied them ever since, focusing on their amazing resilience. In one landmark study, he starved 40 eels for as long as seven months to gauge their ability to survive prolonged drought and food deprivation.

Still curious about the eels, Mr. Starnes flew back to the nature center in Georgia in August 1996, where he met with two men from the Georgia Department of Natural Resources. They were armed with backpack electro-fishing devices, which momentarily stun fish. At the first crackle of electricity, Mr. Starnes quickly saw the orange bellies of three-foot adult eels as they turned rigid in the murky water. "They were thick as hair on a dog's back in there," he recalls. After two hours, they collected 24 eels from three ponds. Mr. Starnes found sunfish and bass in the eels' bellies, and the ponds were depleted of smaller fish.

In the fall of 1997, Mr. Starnes returned to the site with the Georgia DNR, and shocked and scooped up 19 eels. More troubling to Mr. Starnes, though, was the fact that the tropically inclined eels had survived a bitter winter in the Atlanta area that paved ponds with a foot of ice. Mr. Starnes, who by then had taken a job as research curator of fishes at the North Carolina Science Museum, put the eels in a large tank to observe. All of Mr. Starnes's notes jibed with Mr. Liem's observation 40 years earlier. "The limits of their gluttony are hard to establish," he wrote in a paper with Mr. Bryant and others. In captivity, they will eat "minnow after minnow." Particularly eerie was to "walk into a room and have five ominous heads rise to the surface, orient your presence, and follow you about the room with almost demanding expectancy."

A second population wasn't revealed until three years later, in June 1997, nearly 700 miles southeast of Atlanta. A Florida International University student named Carol Curtis was studying electric knifefish, another exotic species. She netted several small baby swamp eels in a pond that drains into a waterway known as canal C-9, north of Miami. She was collecting samples of water hyacinth, an invasive flower species, for her aquarium. The eel found its way to FIU Prof. Joel Trexler, who has a doctorate in biology. "The minute I saw it, I knew it was not from here," he said.

Yet another group of eels emerged around the same time. While driving home to Gainesville, Fla., from a boating seminar in St. Petersburg, Mr. Nico, the federal biologist, wondered if the roadside ditches held any Oriental weatherfish -- a peculiar specimen he was researching whose behavior allegedly can predict weather. In a rural area southeast of Tampa Bay, he eased onto the shoulder of the road and pulled out his pole-nets.

Killer Fire Ants

Mr. Nico, who wrote his thesis on piranhas in South America, knew the area held promise. South Florida is a mecca for more than 100 uninvited, or nonnative, species. Fire ants from South America, for example, harass homeowners, even killing an elderly woman there earlier this year. Melaleuca trees from Australia dry up the Everglades, lowering the water table and creating a fire hazard. In the ditch, Mr. Nico scooped up several Oriental weatherfish and two wriggling eels, each about a foot long. Fascinated, he took them back to the lab at the Florida Caribbean Science Center, where he correctly identified them as Asian swamp eels, a species he studied as a student in South America.

Mr. Nico's boss, USGS branch chief Jim Williams, made the connection with the Georgia eels immediately -- Mr. Starnes was a buddy from years back. News of the eels spread slowly on the scientific grapevine, and a network of scientists formed. Mr. Starnes flew down to Florida to study specimens in the FIU lab. Meanwhile, Prof. Trexler asked his students visiting home in Southern China -- where eels are sold in baskets of grass as food items -- to bring back specimens for comparison. And Mr. Nico brought back some tissue samples of baby eels from Venezuela.

That spring, Mr. Nico sampled the C-9 canal in North Miami, a virtual freeway for exotic fish in Florida. Mr. Nico and his team found "dozens of eels of all different sizes" -- the biggest infestation yet. Mr. Nico began surveying every month with the electro-fishing boat, which stuns fish in a 10-foot radius long enough to net them.

Off With Their Heads

Even with all the technology, the eels are extremely difficult to grab. On a recent return to the site, the boat driver yelled directions to the two men manning the nets. "There he goes! Behind that rock! On the bank!" On a small table on the bank, Jeffrey Herod, clad in a long blue plastic apron, called out the weight and length of each eel. Using a small pair of shears, he cut off the heads, which are helpful in gauging the eels' age. "Watch out for these boys," Mr. Herod said to his staff. "They're bleeders."

Soon several agencies pitched in with research and sampling, including the Florida Fish and Wildlife Conservation Commission, the South Florida Water Management District, the U.S. Fish and Wildlife Service, the National Park Service, as well as the USGS offices in the Caribbean Science Center and the Everglades.

Despite the number of experts involved, though, basic questions remained unanswered. How did the eel get here? How fast and how far can it spread? How do we get rid of it? Theories on their entry are many. The eels could be unwanted aquarium pets dumped into the wild -- pet stores sell baby eels nearby -- or escapees from an aquarium-fish farm, say, during a flood. Another theory is the eels were intentionally introduced as food by Asian immigrants. Considered a delicacy, the eels are cut up in sections, either grilled or stir fried, and served over rice, usually with a sauce.

On Sept. 23, 1998, the Florida scientists flew to Washington to inform executives at the Department of the Interior. Afterwards, the eels were listed by the Aquatic Nuisance Species Task Force, a group of seven federal agencies dedicated to control aquatic nuisances. "The question everybody wanted answered is this: Is there any way to keep this from getting into the park? There was a real desire to contain it or even eradicate it," says Prof. Trexler, who attended the meeting. Among the ideas: a network of underwater electronic fences in strategic locations, similar to the ones used in the Great Lakes region to contain the spread of lamprey eels. The interior department "took it seriously from the beginning," says Prof. Trexler. "They said they'd do everything they can to keep it out of the park. I was amazed at the high level of concern." But the meeting didn't change Mr. Nico's mind. "I just didn't think it could be contained."

'Snakes' in the Nursery

Hurricane Irene slammed the Florida keys in the fall of 1999, dumping more than a foot of rain in the Miami area. In Homestead, pastures turned into lakes. Canals flooded over banks. One alarmed owner of a nursery reported several "snakes" around his business, where large potted palms are sold. Bill Loftas, a senior USGS scientist in the Everglades, investigated. He found his first swamp eel run over in the nursery. The next day, with Mr. Trexler, Mr. Loftas found three dead eels and a live one. More questions demanded attention: Had the eel moved across land? Were these eels from the same family in Miami or in Tampa or even Georgia? Or were they a new population?

This past winter, concerned that the eel had already breached the park, Mr. Loftas took the electro-fishing unit in a marsh boat and searched for hours with an FIU postdoctoral intern. They found nothing. "But that doesn't mean they're not there." Like many of the scientists studying the eel, he believes quick action is critical. "This is not a lot of arm waving," said Mr. Trexler. "This is a real threat."

Over Christmas, Mr. Trexler kept the eel tissue samples from the nursery in his freezer and called Tim Collins, snail specialist and a molecular systematist at FIU. "Could you throw this into your works?" Mr. Trexler asked him. Mr. Collins conducted DNA tests through the Christmas break. "When we found the answer, we were floored," said Mr. Trexler. The eels were a "separate introduction" from previously discovered populations in Georgia, North Miami, and Tampa. After extensive DNA testing, they concluded four different introductions of eels had occurred in the U.S.

After a flurry of exchanged e-mails, phone calls and faxes, state and federal biologists agreed to gather in January at FIU to draw up a plan to deal with the eel. Meetings continued through the winter and spring. Today, USGS scientists, working with researchers at FIU and biologists from the Florida Fish and Wildlife Conservation Commission, are actively and regularly searching waters where the eels were previously found. The USGS is preparing a rapid response team to find and "contain" the eel.

But killing the eels, which are estimated to number in the tens of thousands in the U.S. now, may prove tricky. Dynamite, a crude but effective way to kill fish, doesn't work well on eels because they lack the large air bladder that makes fish susceptible to concussion blasts, and they can retreat to their burrows. Poisoning the entire length of the infested canals still wouldn't kill all eels. In tests using rotenone, a poison that makes it impossible for fish to use oxygen, the eels simply raise their snouts above water and breathe air.

Any such efforts would certainly incite protest over the Everglades. Just two years ago in California, the state Game and Fish Commission poisoned Lake Davis -- the entire lake -- to rid it of northern pike, worried they'd become a threat to native trout. Protests, loud and long, continue today. "Which is worse?" asks Mr. Trexler. "The spread of the invader or the risk associated with containing it?"

Write to Mark Robichaux at mark.robichaux@wsj.com