Identifying the potential of anadromous salmonid habitat restoration with life cycle models

PLoS One. 2021 Sep 9;16(9):e0256792. doi: 10.1371/journal.pone.0256792. eCollection 2021.

Abstract

An investigation into the causes of species decline should include examination of habitats important for multiple life stages. Integrating habitat impacts across life stages with life-cycle models (LCMs) can reveal habitat impairments inhibiting recovery and help guide restoration efforts. As part of the final elements of the Habitat Restoration Planning model (HARP; Beechie et al. this volume), we developed LCMs for four populations of three species of anadromous salmonids (Oncorhynchus kisutch, O. tshawytscha, and O. mykiss), and ran diagnostic scenarios to examine effects of barrier removal, fine sediment reduction, wood augmentation, riparian shade, restoration of the main channel and bank conditions, beaver pond restoration, and floodplain reconnection. In the wood scenario, spawner abundance for all populations increased moderately (29-48%). In the shade scenario, spring-run Chinook salmon abundance increased the most (48%) and fall-run Chinook salmon and steelhead were much less responsive. Coho responded strongly to the beaver pond and floodplain scenarios (76% and 54%, respectively). The fine sediment scenario most benefitted fall- and spring-run Chinook salmon (32-63%), whereas steelhead and coho were less responsive (11-21% increase). More observations are needed to understand high fine sediment and its impacts. Our LCMs were region-specific, identifying places where habitat actions had the highest potential effects. For example, the increase in spring-run Chinook salmon in the wood scenario was driven by the Cascade Mountains Ecological Region. And, although the overall response of coho salmon was small in the barrier removal scenario (6% increase at the scale of the entire basin), barrier removals had important sub-regional impacts. The HARP analysis revealed basin-wide and regional population-specific potential benefits by action types, and this habitat-based approach could be used to develop restoration strategies and guide population rebuilding. An important next step will be to ground-truth our findings with robust empirically-based estimates of life stage-specific survivals and abundances.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Ecosystem
  • Life Cycle Stages / physiology*
  • Oncorhynchus kisutch / physiology*
  • Oncorhynchus mykiss / physiology*
  • Rivers
  • Salmon / physiology*
  • Seasons

Grants and funding

This work was supported by the Washington Department of Fish and Wildlife (WDFW #15-03970) and by the Washington Recreation and Conservation Office (RCO #17-1477). Both were awarded to TJB. One of the funders, WDFW, assisted by providing a portion of the data and local expert knowledge of the study system. The funders provided support in the form of salaries for all authors (JCJ, CN, CF, and TJB). Two authors (CN, CF) were affiliated with a commercial company, Ocean Associates, Inc. These two authors were under contract to the National Marine Fisheries Service and funded under the same contracts; these commercial companies provided no funding for the project. The specific roles of these authors are articulated in the ‘author contributions’ section. Neither the funders nor the commercial company had any additional role in study design, analysis, decision to publish, or preparation of the manuscript.