A desperate fight to save an ugly, fat fish
A fish ladder deep within the Bonneville Dam complex isn't designed for salmon. It's a mock-up of a fish-ladder entrance, part of a little-known...
BONNEVILLE DAM, Ore. — A fish ladder deep within the Bonneville Dam complex isn't designed for salmon. It's a mock-up of a fish-ladder entrance, part of a little-known but urgent drive by federal and tribal agencies to make Northwest dams friendlier to an odd and ancient fish that draws scarce attention and less love.
Once, like salmon, a staple of Native American tribes, the eel-like lamprey are rapidly disappearing. Fewer adult lamprey have passed Bonneville Dam on their way upriver to spawn this year than any year since records have been kept. The number is so low it startles some biologists.
In the upper reaches of the Columbia River and its major tributary, the Snake, lamprey populations are winking out, said Bob Heinith, a biologist at the Columbia River Inter-Tribal Fish Commission. "We're running out of time. We don't have the animals anymore. There's a real sense of urgency."
Lamprey are notoriously poor swimmers and have a tough time climbing fish ladders designed for salmon — which is just about every fish ladder in the Northwest. The mock-up ladder entrance at Bonneville is a kind of lamprey proving ground. Biologists can experiment with configurations easier for lamprey to negotiate, then run lamprey through to see whether they make it.
The Corps of Engineers has installed trial lamprey-passage systems, known as "lamp ramps," more suited for lamprey to latch onto with their suckerlike mouth.
The corps plans to expand the systems next year.
Lamprey are not merely another species in decline. Their disappearance may reverberate through the food chain. They've been called "earthworms of the river" because they dwell as young in the river bottom and are thought to be an important food for species from salmon to sea lions.
Without lamprey, which are richer in fats and easier to catch than salmon, sea lions may prey more heavily on salmon.
Only about half of adult lamprey headed upriver make it past each dam. That means scarcely 10 of every 100 can get past three dams in a row.
Lamprey, which grow about 3 feet long and resemble fat underwater snakes, wouldn't win a piscine beauty contest. They spend their adult lives as parasites, using a suction-cup mouth lined with teeth to suck blood from other fish. That may be why few people have cared much about them compared with salmon.
Once hundreds of thousands of lamprey, weighing many tons, supported commercial harvests at Willamette Falls near Oregon City. Bonneville Dam counts bounced around 400,000 in the 1960s, compared with the 14,000 counted this year.
In a roundabout way, the lamprey's decline may hold a high cost for salmon. Young salmon are thought to feed on juvenile lamprey, benefiting from the lamprey's high fat content.
Lamprey also have long been a key food for seals and sea lions because they're so nutritionally rich and easy to catch. Without lamprey, seals and sea lions might prey more heavily on salmon.
Because lamprey spend more time in rivers and streams than salmon, they also may be more heavily exposed to toxic contaminants. An Environmental Protection Agency study found that lamprey had the highest concentrations of pesticides among migratory fish in the Columbia, probably because pesticides and other toxics accumulate in their fat stores.
Any changes for lamprey are reviewed carefully to make sure they don't interfere with salmon passage, said David Clugston, a corps fish biologist. Because the two species are so intertwined and have similar habitat needs, one will probably not flourish without the other.
"We're not going to get salmon recovery unless we get lamprey recovery," he said. "They're a forgotten species, but these are really important animals."
Copyright © 2008 The Seattle Times Company
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