Why Aren't Salmon Responding to Habitat Restoration in the Pacific Northwest?

Abstract

Declines in populations of Pacific salmon Oncorhynchus spp. in the Pacific Northwest have led to listings under the Endangered Species Act. One objective of current recovery efforts is the restoration of freshwater and estuarine habitats, which had been occurring prior to Endangered Species Act listing but increased dramatically afterwards. However, few listed populations are improving. We believe that there are five factors contributing to the lack of population response to habitat restoration: Not enough restoration has been done. We are not doing the right things in the right places at the right times. Ongoing habitat degradation is offsetting restoration benefits. Not enough time has passed. Monitoring has been inadequate to detect changes in Pacific salmon abundance. All factors contribute to the disappointing progress on Pacific salmon recovery, although their importance varies. Two factors are more consistently significant than the others. Resources available to address habitat damage remain insufficient. The scale of the problem is large, so the response needs to be correspondingly large to yield desired outcomes. Of equal significance is the failure of restoration programs to identify elements controlling fish production. Implementing the right projects in the right places is key to improving the outcomes of restoration.