The Asotin Creek
watershed is located in southeast Washington and is a tributary of
the Snake River. Originating in the Blue Mountains, the Asotin Creek
watershed is a historically productive subbasin for steelhead trout
(Oncorhynchus mykiss) and spring Chinook salmon (O. tshawytscha) (NMFS
1997). Bull trout (Salvelinus confluentus) are also present in the
subbasin (USFWS 2002). There is no historical record of fall Chinook
inhabiting Asotin Creek (ACMWP 1995). However, fall Chinook salmon
(probably hatchery strays) have been observed spawning in the mainstem
of Asotin Creek within the last several years
All populations
of anadromous salmonids in the Snake River Basin are listed as threatened
or endangered by the National Marine Fisheries Service (NOAA Fisheries).
Bull trout are listed as threatened by the U.S. Fish and Wildlife
Service for protection under the endangered species act. Primary threats
to salmonid populations in the Asotin Creek subbasin include out-of-subbasin
hydroelectric dams and associated reservoirs in the Snake and Columbia
Rivers, out-of-subbasin harvest, loss of riparian habitat, water quality,
detrimental changes in hydrology, sediment transport, stream channel
stability, elevated summer water temperatures and lack of in-stream
pools caused by local land use activities (ASP 2004). Many habitat
restoration projects have been completed and are on-going in the subbasin
with state (Salmon Recovery Funding Board) or federal (BPA) funding
to address habitat issues, focusing primarily on population protection
and habitat restoration in Asotin Creek (ASP 2004; BPA 2004).
The State of Washington
has designated Asotin Creek as a wild steelhead refuge (Glen Mendel,
WDFW, pers. comm., 2004), eliminated harvest of adult salmon and steelhead,
strictly limited fishing impacts, and ceased all direct hatchery steelhead
releases since 1998. With little or no influence from hatchery steelhead,
the Asotin Creek watershed provides a wild steelhead system with background
population data to monitor steelhead reproductive biology, population
variation and status over time.
Because of the
complex life history of steelhead trout, accurate estimates of adult
steelhead escapement and natural juvenile production, as well as survival
rates by life stage, are needed to understand salmonid productivity
in Asotin Creek. This assessment is consistent with recommendations
for the Tributary Research, Monitoring and Evaluation (RME) plans
being developed by NOAA Fisheries, which identify the need to better
answer the following questions for indicator steelhead stocks from
ESUs within the Columbia Basin:
1) What is the
size of the population?
2) What is the annualized growth rate?
3) What is the freshwater productivity?
4) What is the population’s age structure?
5) How many are hatchery strays?
In order for appropriate
decisions to be made by State, Tribal and Federal fisheries managers,
concerning the most effective actions to stabilize and rebuild steelhead
and Chinook salmon populations in the Asotin Creek subbasin, accurate
data about the life history and reproductive capacity of these salmonids
is necessary. Baseline monitoring is crucial in documenting recovery
efforts for steelhead persistence, and for the proposed reintroduction
of spring Chinook salmon. Fisheries managers will use the data from
this project for recovery actions and population management. The Asotin
Creek assessment project is necessary to address the reasonable and
prudent alternative (RPA 180) for population status monitoring (i.e.,
abundance, trend, distribution, and variation) required by the 2000
FCRPS Biological Opinion.
The goal of this
project is to determine the abundance and current productivity of
juvenile and adult anadromous salmonids in Asotin Creek (primarily
summer steelhead) above George Creek and estimate life stage survival
rates. Estimates of smolt-to-adult and adult-to-adult survival for
the natural steelhead populations in Asotin Creek will provide the
data necessary to determine if salmonid production in the subbasin
is being limited by within-basin or out-of-basin factors
Objective 1 was
to estimate escapement of hatchery and wild steelhead and salmon into
the Asotin Creek drainage above George Creek. The tasks involved in
this objective included:
1) Design and
obtain permits to improve fish passage and build an adult salmonid
trap at Headgate Dam on Asotin Creek, 2) conduct a NEPA review for
these actions, 3) complete an ESA Section 10 Permit Application,
and 4) complete the project design, statistical design and operational
criteria for the adult (spawner) and smolt (outmigrant) traps to
be used on the project.
Objective 2 was
to coordinate, compile, analyze and report results. The tasks involved
in this objective included: 1) Compile and report results monthly
or quarterly from each task to interested parties, co-managers and
BPA, 2) provide annual reports in electronic format to BPA and interested
parties within the basin, 3) provide data in electronic format to
regional database systems such as PITAGIS, RMIS and StreamNet, and
4) coordinate all actions with fishery co-managers, watershed coordinators
and other interested parties in the basin. In addition, a sub-goal
of this objective was to provide written and oral summaries to interested
parties to ensure timely inclusion of results in planning efforts.
Objective 3, added
on February 4, 2004, was to document juvenile steelhead and salmon
life history patterns, survival rates and smolt production from Asotin
Creek. The task for this objective included the operation of a smolt
trap during the spring of 2004 near Headgate Dam.
