Evaluating the Effectiveness of Assisted Migration and Fish Rescue Programs

Jonathan Armstrong studying isolated stream pools —Jonathan Armstrong, 2018

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Climate change, habitat alterations, and increasing water demands are leaving less water available for streams of the Pacific Northwest. As water levels drop, some small streams become fragmented, transforming from a ribbon of continuous habitat into a series of isolated pools. Fragmented streams pose a serious threat to salmon; juveniles that become stranded in small pools are at increased risk to overheat, starve, or be consumed by predators.

Healthy salmon populations can cope with fragmentation and recover from a bad drought-year. However, many of the salmon populations are endangered and face perennial drought. Managers are increasingly finding endangered salmon stranded in fragmented habitats, facing what is presumed to be certain death. Desperate to help, a small group of managers and conservation stewards are experimenting with fish rescue, capturing juvenile salmon from fragmented habitats and moving them to hatchery-like facilities until they grow large enough to go to sea.

Fish rescue programs exist as small startups handling a tiny fraction of a population. However, there are growing demands to scale-up fish rescue by applying the technique to more fish and across more watersheds. Though fish rescue is poised for rapid expansion, no one has actually evaluated whether it is safe, effective, or feasible at scales that would have meaningful impact. Holding juveniles in captivity increases their immediate survival, but it has also been shown to reduce subsequent survival, for example by decreasing the ability of fish to feed effectively in the wild after being fed in captivity. We will measure the effects of fish rescue at multiple life-stages and analyze the costs and benefits of applying this technique across the Northwest. The final product will be a tool that allows natural resource managers to evaluate the feasibility and effectiveness of fish rescue in the context of their specific watershed and salmon population. 

Lead Investigator:
Jonathan Armstrong, Oregon State University

Other Investigator(s):
Kale Bentley (Washington Department of Fish and Wildlife), Thomas Buehrens (Washington Department of Fish and Wildlife), James Dixon (NOAA National Marine Fisheries Service),

Project Contact:

State: Regionwide

Funding Year: FY 2016

Project Status: In Progress

Topic Category: Fish & Wildlife

Science Agenda Theme: Vulnerability and Adaptation, Communication of Science Findings


Partners: NOAA, WA state

  • Evaluate the efficacy of fish rescue: This project will evaluate how seasonal translocation of fish improves survivorship, so that managers can make informed decisions about whether to apply this climate change adaptation action more broadly throughout the region.
  • Adaptive and customized cost/benefits analysis: The final product will be a tool that allows natural resource managers to evaluate the feasibility and effectiveness of fish rescue for each specific watershed and salmon population under consideration.
  • Columbia River Inter-Tribal Fish Comission
  • National Oceanic and Atmospheric Administration
  • Northwest Wild Fish Rescue
  • WA Dept of Fish & Wildlife