A Vampire Story

Sea lampreys suck. Striking fast as cobras, these primitive, jawless, boneless fish latch onto their prey with tooth-studded disks, bore holes with raspy tongues, then imbibe body fluids. They can suck their way over wet dams and through rocky rapids. They hitch rides by sucking onto boats and humans. In the Great Lakes, Finger Lakes, and Lake Champlain a sea lamprey may kill 40 pounds of salmonids during its 18-month adult phase. When one or several finish with a trout or salmon it looks like Swiss cheese soaked in raspberry jam.

You can suppress sea lampreys by poisoning their mud-dwelling larvae, blocking their access to streams, and disrupting spawning with release of sterile males. But you'll never get them all; and if you don't keep at it, they'll bounce right back. The only sure way to protect game fish is to equip each with a wooden crucifix, at least according to columnist Dave Barry.

Consult most any credible source and you'll learn that sea lampreys are "alien invaders" from the Atlantic that gained access to Lake Ontario and the Finger Lakes through the Erie Canal and to Lake Champlain through the Champlain-Hudson canal. Now two comprehensive studies, still unpublished at this writing, provide compelling evidence that this is not so, that sea lampreys are just as native to these waters as are landlocked salmon to Maine's West Grand, Green, Sebec, and Sebago lakes.

Dr. Kim Scribner, a fisheries professor at Michigan State University, supervised a project that compared the DNA of sea lampreys from Lake Champlain and Cayuga Lake with that of specimens from the Atlantic. "The genetics of the lake fish indicate long isolation," Scribner told me. "If colonization were a human-mediated event, there should be certain genetic affinities between populations." There aren't.

Concurrently, independently and looking at different genetic markers, researchers at the Hudson River Foundation for Science and Environmental Research have reached the same conclusion. "We found tremendous differences in mitochondrial DNA," declares the foundation's Dr. John Waldman. And he adds that because Champlain lampreys don't share DNA with Lake Ontario fish, they probably had a separate history of colonization. Certainly, there is nothing that would have prevented sea lampreys from entering Lake Ontario through the St. Lawrence River and Lake Champlain through the Richelieu River.

The notion that sea lampreys negotiated the Erie and Champlain-Hudson canals is a major stretch. Like other anadromous fish, lampreys require clean, well-oxygenated water, and the canals were filthy and stagnant. They were also choked with locks, and ripe lampreys need to spawn quickly because, like Pacific salmon, they undergo rapid decay. What's more, the sea lamprey (at least in freshwater) is one anadromous fish that doesn't home in on its natal river. Instead, it follows pheromones released by larval lampreys-the presence of larvae means there must be spawning habitat. If sea lampreys arrived from the Atlantic via man-made canals, there wouldn't have been larvae to attract them.

But why and how did sea lampreys negotiate the Welland Canal (which bypasses Niagara Falls) and enter the upper Great Lakes, where they are definitely not endemic? Slowly and in exceedingly small numbers. This relatively short (26-mile) canal was finished in 1829, but it wasn't until 1921 that sea lampreys showed up in Lake Erie. And apparently, not many lampreys made it through because Waldman and his colleagues found far less genetic diversity in Lake Superior specimens.

As recently as last fall the Atlantic Salmon Journal ran a piece in which a misinformed fish writer (one Ted Williams) reported that sea lampreys were probably not native to Lake Champlain and Lake Ontario because "not one of the historical accounts of salmon or lake trout catches mentions a fish bearing a circular wound." But native silver lampreys had been present in both drainages and would have wounded fish, an indication that lack of public commentary on scarring doesn't mean much.

How could Atlantic salmon and lake trout have thrived in the Finger Lakes, and Lakes Champlain and Ontario if sea lampreys had been present? Other documents (such as my master's thesis) contend that lampreys wiped out lake trout in Lake Ontario. But a newly released 15-year study by federal agencies and North American universities, offers convincing evidence that by the 1940's the lake was sufficiently contaminated with dioxin to kill virtually all young trout. Lake Ontario's prolific Atlantic salmon were extirpated in the late 19th century by dams, which also would have knocked down sea lampreys. But a few lampreys survived, and the species exploded when the dams fell into disrepair and when humans replenished the lake with lamprey prey.

Could it have been that the extinct native races of lake trout and Atlantic salmon in Lakes Ontario and Champlain had adapted to sea lampreys? If this were the case, you'd expect the extant native trout from Seneca Lake (one of the Finger Lakes) to be resistant to lamprey attack. Indeed they are-so resistant, in fact, that managers stock them in the Great Lakes where they survive much better than the Lake Superior strain. Perhaps it's a behavioral thing or perhaps, because Seneca Lake is very deep, its lake trout prefer water too deep for lampreys.