Fish Rescue and Relocation
Western Brook Lamprey in Washington County
Operations crews are very aware of the importance of aquatic habitat and the species that reside within the Tualatin Basin. One of the most misunderstood aquatic residents in the basin is the Western Brook Lamprey. Many think they are an eel, but they are actually a Native Migratory Fish. They should be distinguished from the Pacific Lamprey that can be a parasitic nuisance, becoming unwelcome stow-a-ways on the sides of Columbia River Salmon. Pacific Lamprey also plays a significant role in the Native American culture.
As a state protected native fish, the Operations division relocates Lamprey when we salvage fish at our construction sites. We've worked with the Lamprey experts at US Fish and Wildlife Service to develop new techniques for catching and moving these slippery fish. They move quickly within the silts and sediments, much like the sandworms in the movie Dune. By digging lamprey holes in the streambed prior to dewatering, all the lamprey move to the hole once the water becomes low and are quickly scooped up by staff and taken up or downstream of the project.
Brook lamprey are an enigmatic species – after emerging from the redd (nest), they burrow into the sands & silts of our streambeds for up to seven years. They filter feed on algae and other detritus, helping keep the water clean. Once mature, they emerge, spawn and die. Little is known about their courtship and mating rituals. Imagine our surprise at recently finding several breeding pairs right next to a bridge repair project (captured on video on right).
To minimize impact on the fish, we refrained from working near or within the section of the stream occupied by the nests until after the young lamprey emerged. This is one more example being good stewards of our natural resources as well as our road system.