Presenter/s: Robert Bilby
Symposium Session: 2024 - 07 Key Results from Intensively Monitored Watersheds: Incorporating Lessons into Restoration Programs and Project Design
Topics covered: adaptive management and monitoring and fish-salmon
ABSTRACT
Intensively Monitored Watershed (IMW) programs have been active across the Pacific Northwest for over twenty years. These studies were established to determine the contribution habitat restoration can make to salmon recovery and to improve the effectiveness of habitat restoration programs. IMWs couple multiple restoration actions concentrated in a single watershed with intensive monitoring of habitat and fish populations. Recently, two efforts to review the results of regional IMWs and identify management implications have been completed. The Pacific Northwest Aquatic Monitoring Partnership (PNAMP) released a report in 2022 that reviewed results from 13 IMWs in Washington, Oregon, Idaho, and California. This review concluded that certain types of restoration actions, like barrier removal, were consistently associated with positive fish response but some, frequently employed, restoration actions, including wood placement, produced inconsistent fish response. The PNAMP review also concluded that limiting factors often were not accurately identified, limiting the effectiveness of restoration actions and that adaptive management processes were poorly developed in some regions, making it difficult to implement findings from IMWs or other monitoring programs.
Following the PNAMP review, a synthesis of the results from the 5 IMWs funded by the Washington Salmon Recovery Funding Board (SRFB) was initiated. This review was intended to summarize results from each IMW and investigate some of the uncertainties identified in the PNAMP review. As with the PNAMP review, the SRFB IMWs demonstrated consistent, positive fish response to barrier removal, and inconsistent response to wood placement. The IMW data related to wood projects suggests that successful projects require very intensive treatment at a site and often requires multiple treatment applications. The review also found that fish response to restoration was affected by the number of juvenile fish available to utilize habitat created through restoration. In systems with strong density dependence, fish populations should respond favorably to increased habitat. In contrast, in systems with weak density dependence increasing habitat area may not generate a positive fish response; there already is enough habitat to accommodate the juvenile fish. Therefore, restoration actions should couple efforts to increase escapement with restoration treatments that address density-independent mortality factors (e.g., predation). This presentation will explore the most significant results of these two reviews with a focus on implications for restoration practitioners.