OREGON CITY, Ore. - They dove into the cold waters, emerging with writhing, eel-like fish in hand and thrusting them into nets.

Thus began Northwest Native American tribes' annual lamprey harvest at a rushing, 40-foot waterfall about 15 miles south of Portland.

The jawless, gray fish are a traditional food source for tribal members in the Columbia River Basin, which stretches from the Oregon coast to Canada and into Idaho, Montana and Washington. Lampreys grow to about 2 feet long and are prized for their rich, fatty meat.

On Friday, adults, teens and children from the Umatilla and Warm Springs reservations in Oregon and the Yakama reservation in Washington crawled over slippery rocks and waded through icy pools to reach the lampreys' hiding spots. The fish latch onto rocks in Willamette Falls with their round, toothy mouths.

"Our people have always come here, generation after generation," said Bobby Begay, a Warm Springs tribal member who drove more than a 100 miles to the falls from his village of Celilo.

Begay, 46, has attended the harvest for more than 40 years. He is teaching his children and nephews how to navigate the rocks and where to find the biggest catch.

"The same fishing holes my grandfather showed me, his father and grandfather showed him, and I showed my kids," he said.

Lampreys taste best when roasted over an open fire, Begay said. They also can be dried or frozen for later use. The fish harvested this month will be distributed to tribal elders and used for ceremonial purposes, he said.

In previous generations, lampreys were abundant up and down the Columbia River and its tributaries. Biologists have estimated at least a million once were crossing Bonneville Dam on the Columbia east of Portland.

But their numbers have dwindled over the past 30 years because of the dams and toxins such as pesticides. About 20,000 remain, said Brian McIlraith with the Columbia River Inter-Tribal Fish Commission.

Willamette Falls is the last place where the fish can be caught by the hundreds.

Tribes have received funding and run research and recovery projects. They truck lampreys past dams and have pushed for construction of ramps to help the fish navigate the structures.

They're also looking at breeding lampreys in a hatchery, but that's not the preferred method, said tribal elder Donnie Winishut Sr., who observed the harvest to assure safety.

"We would rather see them grow in a natural way," Winishut said. "It's good to see the young people coming to the falls and learning our tradition, and I hope they can continue coming here to catch the fish."