Another Successful Year for the Columbia River Fish Trap

For Wild Fish Conservancy’s (WFC) field research staff, there was a lot to celebrate as 2019 drew to a close. In November, WFC wrapped up seven months of intensive fisheries research and an entire year’s worth of careful planning, engineering, and construction at the Columbia River fish trap near Cathlamet, WA. It was WFC’s most successful year of selective harvest research to date, with results showing incredible promise for development of sustainable salmon fisheries that stand to benefit threatened populations of salmon and steelhead trout, endangered Southern Resident killer whales (SRKW), and coastal fishing communities of the region.

We began 2019 with major announcements from the National Oceanic and Atmospheric Administration (NOAA) Fisheries Service, awarding WFC two prestigious national grants: the National Bycatch Reduction Engineering Program (BREP) Award and the Saltonstall-Kennedy Award. Continued support from NOAA Fisheries Service enabled WFC to expand its historic research project in the lower Columbia River, modifying and evaluating WA State’s first commercial salmon trap in over 85 years as a sustainable alternative to conventional gillnetting.

Prior years of research from 2016-2018 had shown the potential of the tool to selectively harvest hatchery salmon while releasing threatened and endangered bycatch unharmed. While gillnets commonly result in bycatch mortality rates ranging from 45-48% for steelhead trout and Chinook salmon, fish traps can reduce bycatch mortality to roughly 1-6%. Despite such promising results from the prototype fish trap design, WFC staff set lofty goals in 2019 to eliminate bycatch mortality altogether through modification of the prototype trap in the Cathlamet Channel, WA.

WFC biologists began modifying the fish trap last January, working in the ice and snow to complete the gear in time for deployment during the spring fishery on the Columbia River. As the ice thawed in March, high river flows and debris posed new challenges to WFC researchers constructing the trap in the lower Columbia River. Nevertheless, modifications and deployment were completed in time for the late-spring fishery.

As WFC’s major peer-reviewed publication in Fisheries landed in May, field staff began testing the fish trap for the first time in spring and early-summer fisheries of the Columbia River. The team tagged nearly 850 sockeye salmon and tracked their detections upriver to estimate post-release survival. As we hoped, the treatment group of sockeye salmon that was exposed to the new commercial capture process—in which fish were passively captured one-by-one without air exposure, handling, or entanglement—experienced no detectable release mortality effect. In other words, the new passive fish trap design resulted in 100% relative survival of sockeye salmon bycatch over a 400 km (~250 miles) migration to McNary Dam (Relative Survival = 1.017, SE = 0.032).

Beginning in August, WFC once again joined forces with commercial fisherman Blair Peterson, processor and fish buyer Mike Clark of C&H Fish Company, and the Washington Department of Fish and Wildlife (WDFW) to evaluate the performance of the fish trap in a commercial, selective harvest setting. Like all other test fisheries in Washington, any fish harvested are immediately property of the state. A fish buyer then purchases the fish from WDFW at market price and the revenue from that sale helps to offset the cost of future test fisheries deemed necessary by the state. Using a portion of the test fishery revenue and other state funding, WDFW contracts a local commercial fisher to operate the gear and also funds WDFW staff time and their research activities related to the project. WFC serves a strictly research role and does not receive any profits from the sale of fish.

As in the summer and fall of 2018, thousands of hatchery salmon selectively harvested from the fish trap began making their way across the country to high-end restaurants and markets, adding to the trap-caught fish’s reputation for sustainability and quality. Throughout the season, demand was high, with renowned chefs like Renee Erickson praising the fishery and serving trap-caught salmon to customers in the Seattle area.

The late-summer and fall test fishery demonstrated to buyers and consumers of the region that commercial fisheries—when operated in-river with selective gears—can be truly wild salmon and orca-safe. While the trap was operating commercially from August through October, it encountered over 4,200 adult salmonids—with zero immediate mortalities to wild salmon or steelhead. All salmon harvested were of hatchery-origin (addressing genetic and ecological threats posed by their escapement to wild salmon spawning grounds) and were captured in-river, after orca whales had the chance to secure their food needs in the ocean.

With test fishing complete, WFC accomplished one final research investigation in October: a coho salmon post-release survival study with the modified trap design. Analogous to prior studies conducted by WDFW, staff researchers captured fish with the trap and held a sub-sample for a 48-hour observation period. Data collection occurred day and night; a grueling schedule over a particularly windy and frigid October. Over the course of the study, cumulative survival of coho salmon was directly estimated at 100% (Survival = 1.000, CI (S ≥ 0.978) = 0.95). Regardless of the survival estimation technique employed (48-h holding and observation for coho salmon, or mark-recapture for sockeye salmon), the modified trapping technique demonstrated no detectable impact on salmon release survival. These impressive findings suggest that fish trapping may hold potential to nearly eliminate bycatch mortality in constrained commercial salmon fisheries: a win-win for wild fish and fishermen of the region.

Covered in sweat, slime, and algae during a freezing cold week in November, it’s safe to say that WFC’s field staff were relieved at the completion of this groundbreaking seven-month study. It was an incredibly successful year for the WFC field crew, capped with yet another major federal award from the NOAA Fisheries Service BREP to expand fish trap research to the Oregon side of the lower Columbia River. WFC also joined in a new partnership with the Lax Kw’alaams First Nation with whom we’ll work to construct a fish trap along the Skeena River in British Columbia. Settling in for a bit of peace and quiet in December, WFC will review and write up the 2019 results and brace for yet another eventful year of selective harvest research on the lower Columbia River in 2020, continuing our work to expand fish trap research to other locations in the Pacific Northwest.