Coho Salmon Population Changes Following Large Wood Introductions

In the Oregon Coast Range, reduced stream habitat complexity limits many coho salmon populations, especially during winter when juveniles need refuge from high flows. Large wood (LW) restoration is widely used to improve this habitat, but long‑term, basin‑scale evaluations are rare. Over a 15‑year period, we used a BACI design to assess overwinter survival in a restored basin (Mill Creek) and a reference basin. LW placement led to a small but positive increase in juvenile survival, with the strongest response in medium‑sized fish that likely gained new refuge opportunities. These results highlight that benefits of LW restoration may vary across size classes and that understanding population structure is important for evaluating long‑term restoration effectiveness.