Selected for FY21 funding under PLCI umbrella project:

Practitioners question the effects of Stage 0 restoration on this species in particular. Process based restoration of a depositional valley bottom to pre-disturbance (Stage 0) using Geomorphic Grade Line methodology (Powers et al. 2018) resets a simplified river channel to its natural
complexity (Cluer and Thorne 2013; Castro and Thorne 2019). Stage 0 restoration can create exponential increases in wetted with diverse and complex habitat. Anecdotally, Stage 0 restoration appears to increase rearing habitats for Pacific Lamprey (Kate Meyer, Matt Helstab, Paul Burns, U.S. Forest Service). However, the extent to which Stage 0 restoration affects occupancy and relative abundance of larval lampreys has not been assessed.

This proposed assessment seeks to answer three questions: How does the probability of occupancy of larval lampreys:
1) Differ between Stage 0 restoration sites and control reaches (i.e., pre-restoration or adjacent, non-restored habitat conditions)?
2) Differ between two sites (coastal and western Cascades) undergoing Stage 0 restoration?
3) Change over time at the two Stage 0 restoration sites (i.e., over the course of the restoration)?

This work will assess occupancy of larval lamprey throughout two study sites undergoing Stage 0 restoration (i.e., South Fork McKenzie and Fivemile-Bell). Sampling will follow established procedures for probabilistic assessment of occupancy of larval lampreys, using lamprey-specific
electrofishing field methods and a spatially-balanced, generalized random tessellation survey (GRTS) design to select sampling sites (Harris et al. 2016, 2019). Surveys will be completed in multiple microhabitat types and will allow a rigorous estimation of the probability that larval lamprey will occupy a given microhabitat in Stage 0 restoration sites and adjacent control reaches. The exact number of microhabitats to be assessed will depend on statistical power analyses, based on habitat area to monitor.