Assess Salmonids in the Asotin Creek Watershed: 2005 Annual Report

The goal of this project is to assess the status of anadromous salmonid populations in the Asotin Creek watershed. This project implements the research, monitoring and evaluation (RM&E) criteria specified in the Asotin Subbasin Plan by providing estimates of abundance, productivity, survival rates, and temporal and spatial distribution of ESA-listed species, primarily summer steelhead (Oncorhynchus mykiss) and secondarily spring Chinook salmon (O. tshawytscha). The project also implements reasonable and prudent alternative (RPA) 180 in the NMFS 2000 and 2004 Federal Columbia River Power System (FCRPS) Biological Opinions (BiOp) for population status monitoring and review of status change over time. This project is designed to enumerate adult salmonids entering Asotin Creek to spawn and to estimate the juvenile migrant population and emigration patterns. The mean juvenile steelhead population was estimated at 45,744 juveniles for 2004 and 27,287 juveniles for 2005. More than 500 adult steelhead were captured in 2005 (the first season of adult trapping in Asotin Creek), resulting in a population estimate of 653 adults, spawning in approximately 46 km of accessible steelhead habitat above the trapping location (near river km 7.0). In addition, there was a significant population of steelhead spawning in the 2.4 km between the adult trap and George Creek. The data suggests that the Asotin Creek summer steelhead â€" above eight mainstem dams on the Snake and Columbia Rivers â€" are a productive, naturally-producing population of the Snake River steelhead ESU.