This annual report is one in a continuing series describing WDFW’s progress toward meeting
summer steelhead and rainbow trout mitigation goals established in the LSRCP.
Stocking of LSRCP-produced rainbow trout within Washington, and transfers to the State of
Idaho generally went as planned, though in 2007 and 2008 there was a shortfall in rainbow trout
production and not all LSRCP goals were met. Hatchery survival and smolt release goals for
summer steelhead were met for both years. Adjustments were made to the marks and tags
applied to the summer steelhead over the reporting period.
We continued smolt trapping on the Tucannon River to estimate the number of migrant
steelhead. In the 2006/2007 and 2007/2008 we estimated 11,546, and 26,099 total migrants,
respectively. Mean smolt size and peak of out-migration for both years was similar to previous
years. Average smolt-to-adult survival of wild origin summer steelhead from the Tucannon
River (based on the PIT tags) was 2.25% back to Bonneville Dam, and 1.75% to McNary Dam.
PIT tag detections of naturally produced Tucannon River steelhead exhibited a disturbing
migration pattern, with about 50% returning to and remaining above Lower Granite Dam. This
same migration pattern has also been observed in the Lyons Ferry stock fish and the Tucannon
River hatchery endemic stock steelhead.
As part of our ongoing annual broodstock collection and research activities, WDFW hatchery
and evaluation staff operate a series of traps in southeast Washington. We reported the number
of fish captured and released at all trap locations, composition of hatchery and wild origin fish,
coded-wire tag recoveries (where appropriate) age composition, eggtake and fecundity estimates
from spawning activities, and historical spawn timing for each steelhead stock.
WDFW staff surveyed steelhead sport anglers during the 2006/2007 and 2007/2008 sport fishing
season within the LSRCP area of Washington to recover CWTs from tagged steelhead. In
2007/2008, creel surveys, on the Tucannon, Touchet or Walla Walla rivers were limited or not
conducted. This was done to increase our sample rate in the mainstem of the Snake River to
achieve at least a 20% sample of what is eventually reported on Washington’s catch record cards.
During the springs of 2007 and 2008, evaluation staff conducted spawning ground surveys to
estimate the number of redds in index areas of the Tucannon and Touchet rivers and Asotin
Creek. Stream flows were favorable in 2007, but were high and turbid during 2008 which
greatly affected our ability to estimate redds in the Tucannon River. Evaluation staff
standardized all spawning ground survey estimates for summer steelhead in the Touchet River
and Asotin Creek.
Coded-wire tag recoveries from fisheries, hatcheries, or from traps in river have provided the
basic data to estimate minimum smolt-to-adult return rates on LFH and Wallowa stock summer
steelhead from the program. Due to a variety of factors, smolt-to-adult survivals back to the
project area have generally been nearly 3 times the assumed rate. The LFC summer steelhead
program (LFH and Wallowa stock only) continues to meet and/or exceed its original mitigation
goals by supplying large returns of hatchery steelhead for harvest to the Snake River area. This
is mainly due to the fact that harvest rates in the lower Columbia River fisheries have declined
substantially since the program was initiated. Hence more fish are returning to the project area
even though hatchery production has been reduced in recent years.
As in previous years, WDFW electrofished using either a multiple or a single pass removal
method at index sties to estimate Age 0 and Age 1+ juvenile steelhead densities and derive
population estimates for specific river reaches. During the summer of 2005 and 2006, we tested
estimator bias (multiple pass estimate vs. mark/recapture estimate) at 44 sites in SE Washington.
For both years on average, we found that multiple pass underestimated Age 0 and Age 1+
summer steelhead by 29.9% and 22.7%, respectively, compared to the mark/recapture estimate.
Based on these results, and other factors such as high confidence intervals around the
electrofishing estimates, we have discontinued electrofishing surveys for juveniles.
