A prototype structure is in place at McNary Dam that could help Pacific lamprey as they migrate up the Columbia River.
Crews finished installing the 40-foot-long structure Feb. 26, designed to allow for easier passage of eel-like lamprey past the dam. It comes as part of a 10-year agreement between federal agencies and Northwest tribes -- known as the Columbia Basin Fish Accords -- to benefit salmon, steelhead and lamprey survival.
Once regarded as a "trash fish" in Northwest rivers, lamprey remain a culturally significant food and resource for tribes across the region. Though not protected as an endangered species, certain populations have dwindled the last 30 years.
Lamprey are an anadromous fish, meaning they migrate from freshwater rivers to the ocean before returning to spawn. They are physically unable to pass over traditional fish ladders, preferring lower routes while moving primarily along the bottom of the river.
The U.S. Army Corps of Engineers made numerous adjustments to fish ladders in recent years to assist with lamprey-friendly passage. Metal plating attached along ladder floors and orifices in weirs created smoother surfaces for lamprey to attach with their sucker mouths and travel through the facilities.
But the prototype at McNary Dam is first-of-its-kind, built specifically with lamprey in mind. The Corps will test the structure for two years, with video monitoring and transponder-tags detectors. If successful, the agency will make it a permanent addition at the dam.
"Lamprey are a very important part of the ecosystem," said Mark Smith, project manager with the Corps' Walla Walla District. "All the dams to have an impact on their passage ... this is a culmination of our research to this point."
Marine Industrial Construction of Wilsonville built, delivered and installed the device at a cost of $336,542. It is now underwater at the downstream end of the Oregon shore fish ladder.
A series of obstructions are welded inside the structure to create a variety of flow velocities across the width of the interior. Researchers can then determine which conditions are best suited for lamprey passage.
Tracking lamprey populations is a tricky task, as the fish do not migrate like salmon. They are quite nebulous, and do not demonstrate a homing instinct to return to their basin of origin. Historical counts are also unverified.
The Confederated Tribes of the Umatilla Indian Reservation began lamprey research and restoration in 1994. The fish were poisoned twice in the Umatilla River in 1967 and 1974 as part of an effort to clear more habitat for salmon and steelhead.
Aaron Jackson, CTUIR lamprey project leader, previously said the goal is to restore self-sustaining levels. They counted approximately 350 adults in 2013, Jackson said, which is a step in the right direction.
Better passage can help in that effort. Smith said lamprey are important to the health of the river system, acting as filter-feeders in gravel and sand before they begin migration.
The ecosystem is quite complex, Smith said, and they shouldn't let one part of that continue to fade away.
"We need to make our ladders as safe as we can, so when they're here they can get over safely," he said.
For more information about fish passage work in the Columbia River Basin, visit the Federal Caucus website at www.salmonrecovery.gov.
Contact George Plaven at firstname.lastname@example.org or 541-564-4547.
This story originally appeared in East Oregonian.