Historical And Current Presence Absence Of Coho Salmon Oncorhynchus Kisutch In The Central California Coast Evolutionary Significant Unit PDF Download

A summary of the presence and absence of coho salmon, Oncorhynchus kisutch, in streams in the Central California Evolutionary Significant Unit (ESU) with historical records of this species has been prepared to assist in the Endangered Species Act listing process. Presence-absence data were used because of: 1) the short time frame indicated by the listing process, and 2) the use of presence-absence data in pre-listing documents. Presence-absence data used here come form surveys conducted for this study and from data collected by other researchers. Coho salmon were absent from 50% of the historical record streams. This figure is similar to reports by earlier researchers. The percent of historical record streams with coho salmon absent is highest in the highly urbanized San Francisco Bay and the lowest in coastal Marin County. Percent of absence was also high in Sonoma County, with other areas being roughly equal.