Coho Smolt Monitoring

2015 Smolt Trap Counts


Funnel net traps are operated on Mill and Willow creeks each spring to monitor the downstream migration of coho smolts. In past years, smolt traps were also operated on Green Valley, Sheephouse and Ward creeks. Captured coho, Chinook and steelhead are counted, weighed and measured, scanned for coded-wire and/or PIT tags, and possibly sampled for genetics before being released back into the creek. Each fish is also checked for the presence of an adipose fin clip to determine whether it is a hatchery-released program fish (clipped adipose fin) or a wild fish (intact adipose fin). All other fish, amphibians, crustaceans and other aquatic species are counted and recorded.


The data from downstream migrant smolt trapping allows us to determine minimum smolt counts, overwinter survival of fall-released program coho, average smolt size, and growth of PIT-tagged fish. Trapping also offers an opportunity to collect genetic samples from wild coho smolts to determine whether they are offspring of wild adults or Broodstock Program fish. CWT locations and PIT tag numbers denote release stream and season for tagged fish, which allows us to evaluate the effectiveness of different stocking strategies for adaptive management feedback to the Broodstock Program.