Clackamas River Bull Trout Reintroduction
Placing bull trout on the path towards recovery

by Chris Allen and Marci Koski

“I was up the bank lying full length on the sweet-scented grass and gasping in company with my first salmon caught, played and landed on an eight-ounce rod. My hands were cut and bleeding, I was dripping with sweat, spangled like a harlequin with scales, water from my waist down, nose peeled by the sun, but utterly, supremely, and consummately happy.”

The famous English author Rudyard Kipling made this claim after spending a day fishing for steelhead and salmon on the lower Clackamas River in 1889. While the River and its famous steelhead (Oncorhynchus mykiss) and salmon runs look quite different today, it is still a gem of a Pacific Northwest river—flowing west from the flanks of the Cascades Mountains through wilderness and old-growth forest and eventually meandering through productive agricultural lands before entering the Willamette River near Portland Oregon. The river boasts a full complement of steelhead and salmon and resident fish species, with a single exception—bull trout (Salvelinus confluentus). Although regularly documented in the watershed in the early to mid-1900s, no one, until recently, had observed a bull trout in the River since 1963. With a reintroduction of bull trout underway, it is hoped that observations of bull trout in the river will become more commonplace.

The bull trout is native to the northwestern United States and British Columbia. Like most species in the char family, the bull trout has an affinity for cold water, and requires it for successful spawning and early juvenile rearing. The species is most commonly found in moderate to high elevation freshwater environments and though still widely distributed, the bull trout was listed as threatened in the United States under the Endangered Species Act (ESA) in 1999 due to the magnitude of threats and population decline across its range.

Early discussions regarding the reintroduction of bull trout in the Clackamas River Basin were supported by guidance in the species' draft recovery plan, and by biologists working in the basin who believed the factors that caused the bull trout to disappear, such as poor fish passage over dams, habitat modification, and overfishing, had been remedied. With key support from the U.S. Fish and Wildlife Service (Service), Oregon Department of Fish and Wildlife (ODFW), and the U.S. Forest Service (USFS), a reintroduction feasibility assessment was conducted, concluding in 2007 that reintroducing bull trout to the Clackamas River was biologically feasible.

Some lingering concerns regarding the reintroduction included increased regulatory requirements associated with releasing the federally threatened species to the watershed, along with potential predation and competition impacts from bull trout on several stocks of federally threatened salmon and steelhead species present in the basin. To address these concerns, biologists used increased management flexibility under section 10(j) of the ESA to promote the reintroduction project. The decision to use the special 10(j) provision to facilitate a reintroduction of bull trout in the Clackamas was widely supported by state and federal partners, and other stakeholders.

The goal of the adaptively managed reintroduction effort, which was initiated in 2011, is to reestablish a self-sustaining population of 300 to 500 spawning adults in the Clackamas River by 2030.

Project costs and the relative abundance of a suitable donor stock in the Metolius River basin led the implementation team to favor direct transfer of wild donor stock over other alternatives such as artificial propagation or captive rearing of wild juvenile bull trout. The team intends to directly transfer various life stages of donor stock – approximately 60 adults and subadults and as many as 1,000 juveniles annually – to suitable habitat in the Clackamas River.

Since the start of the project, 118 adult and subadult bull trout, and approximately 570 juveniles have been translocated to the Clackamas River. For monitoring and evaluation purposes, all individuals were PIT (passive integrated transponder) tagged, and older life stages radio tagged.

The monitoring program for this effort will help biologists determine whether the Metolius bull trout donor population is sufficiently large and healthy to provide donors annually to the Clackamas, if translocated bull trout are surviving and reproducing in the Clackamas River, and if listed salmon and steelhead are affected by reintroduced bull trout in the Clackamas River. Additionally, the monitoring program will track what habitats fish occupy and their behavior in those locations (e.g., spawning, migrating, etc.).

So far, the Metolius River continues to maintain a healthy bull trout population suitable for contributing donor stock. In both 2011 and 2012, subadult and adult bull trout stayed mostly within in the Clackamas River Basin, and survival rates were as expected. No bull trout resided for a significant amount of time in areas where migrating juvenile salmon and steelhead are artificially concentrated and vulnerable to predation (i.e., Clackamas River hydroelectric facilities). In both years, reintroduced bull trout were observed spawning in a headwater tributary, along with the identification of several redds, or nests—an encouraging finding for the early stages of this important bull trout recovery project.

 

Chris Allen, a biologist with the Service's Oregon Fish and Wildlife Office can be contacted at chris_allen@fws.gov or 503-231-6179. Marci Koski, a supervisory fish and wildlife biologist in the Service's Columbia River Fisheries Program Office, can be reached at marci_koski@fws.gov or 360-604-2500.

For more information, please visit the project's webpage.