Development and Application of Anchor Habitat Approaches to Salmon Conservation: A synthesis of data and observations from the Napa watershed, California.

Since the early 1990’s, the idea of protecting the best habitats as the first step in restoration has been gaining acceptance (e.g. FEMAT. 1993, Doppelt et al. 1993, Dewberry 1996). For the terrestrial environment, unmanaged vegetations stands are recognized as the key component of the best. There has been considerable debate about how to determine what constitutes the best with regards to the aquatic environment.
Ecotrust, Oregon Trout, and The Wild Salmon Center (2000) proposed the concept of salmon anchor habitat for the Tillamook and Clatsop State Forests on north coast of Oregon. A salmon anchor habitat is a reach of stream and its associated watershed that produce a higher than average number of salmon given their area during all years. They form the core of salmon production particularly when population numbers are low. The concept was based on two assumptions: 1) That all parts of the watershed are not equally important for salmonids species; 2) These high production areas, while dynamic on long time-scales, are conservative over the decade to decades time scale.
The assumption that all parts of a river system are not equal for salmonid production has recently been suggested by several observations. Reeves (unpublished data from the 1980’s in: Hobbs, S.D. et al. 2002) identified “hot spots” (high juvenile salmonid production) in the Elk River basin on the south coast of Oregon. Also, indirect evidence that all portions the watershed are not equal for salmonids production is provided by the experience of the Oregon Department of Fish and Wildlife. During the 1990’s their standard index reaches to estimate adult coho (Onchorynchus kisutch) escapement did not detect a decline in the populations along the Oregon coast. When the sites were randomized they found that the standard index reaches overestimated the populations.