The main goal of the Asotin Creek Salmon Population Assessment is to fully understand the biology of the Asotin Creek steelhead population, with an eye towards future delisting.  The Asotin Creek steelhead population is medium size, naturally produced, ESA-listed population of steelhead in the Interior Columbia Basin that is self sustaining.  One portion of this population averages more than 500 spawning adults and more than 40,000 juveniles in just 46 kilometers, in the Asotin Creek mainstem, above river kilometer 6.0.  The Asotin Creek steelhead population may be at or above Viable Salmonid Population (VSP) thresholds.

The Asotin Creek subbasin is comprised of 83,850 hectares in Asotin and Garfield Counties in Washington, and includes Asotin Creek, Tenmile Creek, Couse Creek, Alpowa Creek, and tributaries.  The Asotin Creek salmon population, as named by the NOAA Fisheries Technical Recovery Team (TRT), includes Asotin Creek, George Creek, Tenmile Creek, Couse Creek, and Alpowa Creek.  The Asotin Creek mainstem is comprised of several major tributaries, including the North Fork, South Fork, Charlie Creek, and George Creek.  This research, monitoring and evaluation (RM&E) project provides estimates of abundance, productivity, survival rates, and temporal and spatial distribution of ESA-listed summer steelhead, Oncorhynchus mykiss, for the Asotin Creek steelhead population.  

This project began in 2004, with the monitoring of juvenile salmonids in the Asotin Creek mainstem.  As of 2005, the basic data collection methods include, but are not limited to, the following:  Adult salmonids entering the Asotin Creek mainstem and its tributaries to spawn are enumerated using a floating, resistance board weir.  The juvenile emigrant salmon population is estimated using a rotary screw (smolt) trap.  As of December 2010, this project has collected six years of adult salmon data and seven years of juvenile data.  The data collected describes a persistent steelhead population, that is variably affected by stray hatchery steelhead, which remains large for a subbasin of its size, especially when compared to other steelhead populations in the Columbia Basin.  This fact makes it a desirable reference stream for steelhead supplementation monitoring in the inland Columbia Basin.  

The concept of supplementation has come to the forefront of salmon conservation in the Columbia Basin.  However, the effects of supplementation are not fully understood, and a significant difficulty in evaluating the effects of supplementation is due to the lack of reference (i.e., control) streams.  Having appropriate reference streams is essential for evaluating the true costs and benefits of supplementation.  As a matter of fact, Asotin Creek may be the only reference stream that is collecting the wide array of data necessary to evaluate the effects of steelhead supplementation:  A critical unknown in the Columbia Basin.  Therefore, while this project provides population data on adult and juvenile salmon abundance, we believe its greatest value may be as a reference stream.

Asotin Creek is a scientifically sound reference stream and -- given the lack of un-supplemented reference streams for supplementation effectiveness monitoring -- has one of the few steelhead populations that can provide reference data for understanding wild steelhead biology.  Using the Asotin Creek Salmon Population Assessment project to provide reference data for evaluating the effects of steelhead supplementation as a recovery tool in the Columbia Basin is supported by the co-managers and associated fish management agencies:  NOAA Fisheries, the WDFW, Snake River Salmon Recovery Board, the Nez Perce Indian Tribe, Oregon Department of Fish & Wildlife, Wells Hatchery Committee, and the Washington State Governors' Salmon Recovery Office (GRSO).  This project is RECOMMENDED FOR FUNDING in the 2008 FCRPS Biological Opinion (BiOp).

The GRSO designated Asotin Creek as an Intensively Monitored Watershed (IMW) in 2008.  This designation is part of the "Comprehensive Monitoring Strategy and Action Plan for Watershed Health and Salmon Recovery" for the state of Washington, which created IMW's to determine the response of salmon to habitat restoration efforts.  The GRSO provided about $89,540 (no overhead; 48% cost share) to this project in FY09, which covered almost half of the cost of the work described in the FY09 SOW.

The objectives of this project are to:  1) Estimate spawner abundance and escapement of wild and hatchery steelhead in the Asotin Creek salmon population, 2) estimate adults per redd in the Asotin Creek mainstem, 3) document juvenile steelhead and Chinook salmon life history patterns, survival rates and estimate emigrant production in the Asotin Creek mainstem, and 4) provide and Annual Report and disseminate data from the Asotin Creek Salmon Population Assessment project.
To meet these objectives, we plan to operating 5 adult steelhead weirs and continued operation of the juvenile smolt trap. The juvenile smolt trap is now located at RKM 3.0. Weirs will be installed on Asotin, Alpowa, Couse, George and Tenmile Creeks. Spawning ground surveys to assess adult spawner abundance will be conducted when conditions allow, with assistance and funds from the WDFW Snake River Lab, and funds from LSCRP.