Cooperative Fish and Wildlife Research Units Program: California
Education, Research and Technical Assistance for Managing Our Natural Resources

Project objectives are three-fold: 1) to count the number of live adult fish, redds (nests), and carcasses of Coho Salmon and other anadromous salmonids which are returning to Prairie Creek to spawn; 2) to estimate freshwater survival and outmigration timing of tagged juvenile Coho Salmon; and 3) to estimate the population sizes of outmigrating Coho Salmon and other salmonids. Enumeration is adult salmon will be achieved by ground survey (on foot) of stream reaches by a survey crew of 2-4 people every two weeks during the spawning migrating period (mid-November through mid-March each year), as stream conditions allow. Freshwater survival and outmigration timing of juvenile Coho Salmon will be estimated using mark-recapture methods by a) sampling fish using seines each fall; b) tagging a subset of the juvenile Coho with PIT tags and releasing them at the location of capture; and c) detecting the fish at fixed in-stream antenna arrays or recapturing them in a downstream migrant trap, as the fish move downstream in the fall or during the spring outmigration period (March – June). Fish captured in the downstream migrant trap will be identified, enumerated, scanned for the presence of tags, and released. The long-term goals of the project are to determine baseline and status/trend population information for Coho Salmon and other anadromous salmonids which can be used to identify factors limiting species recovery and to identify restoration needs in the basin. The adult counts and outmigrant smolt counts will provide estimates of fish in and fish out, that can be used to provide relative estimates of freshwater and marine survival. This information is essential to understanding whether changes in salmonid numbers are due to recovery from improvements in freshwater habitat coniditons or changes in ocean conditions. The freshwater survival and abundance and size of yearling Coho Salmon smolts emigrating from Prairie Creek can be used as the benchmark for other streams because much of Prairie Creek is in pristine condition. This project continues a 9-yr data set in Prairie Creek of adult Coho Salmon counts, and a 6-yr data set of smolt counts.