As part of the
Lower Snake River Compensation Plan (LSRCP) mitigation program, Lyons
Ferry Complex (LFC) released summer steelhead into area rivers, and
rainbow trout were stocked into local lakes and rivers during the
springs of 1999, 2000 and 2001. Additionally, fry and fingerling rainbow
trout were reared and provided to Idaho.
During 1999-2001,
groups of juvenile steelhead were freeze branded, coded-wire tagged
(CWT), Visual Elastomer (VI) tagged, adipose and ventral fin clipped
and released into the Tucannon, Walla Walla, Touchet, Snake, and Grande
Ronde rivers. Not all release locations were given marked groups during
the three release years. In addition, Passive Integrated Transponder
(PIT) tags were inserted into many of the hatchery origin study groups
to monitor their migration timing and success through the Snake and
Columbia River dams. Natural origin steelhead from the Tucannon River
were also tagged at the Tucannon River smolt trap. Detection rates
and migration timing varied among the groups but appear to be directly
related to bypass efficiency at each collector facility.
Residualism of
hatchery released steelhead in the Tucannon River was monitored through
hook and line methods in 1999. Residualism rates were similar to previous
estimates. During 2000, intensive creel surveys were conducted on
the Touchet River to assess impacts on natural origin steelhead. Impacts
to natural steelhead from the trout fishery appear to be minimized
by angler preference for larger sized fish.
Natural origin
steelhead have been captured at the Tucannon River smolt trap during
all three run years. Age, length, and total estimated number of smolts
varied slightly between years, which was likely due to environmental
conditions and number of spawning adults. Peak outmigration was similar
among the years.
Adult trapping
was accomplished at numerous remote traps and hatchery facilities
during the study period. Adult collections occurred at Lyons Ferry
Hatchery and Cottonwood trap for the collection of standard hatchery
broodstocks (Lyons Ferry and Wallowa stocks). In addition, endemic
broodstock programs were investigated and initiated on the Touchet
and Tucannon rivers. These programs may eventually replace the Lyons
Ferry Stock in each of the rivers. Efforts to date have been successful,
with improved stock performance (survival) in the hatchery for both
stocks. Test trapping was also conducted on small tributaries of the
Grande Ronde to assess the potential for endemic broodstock development
to replace the Wallowa stock. Results from these traps were not encouraging,
as numbers of natural fish were too low to develop programs. Many
hatchery fish were captured, indicating that the stocks were likely
a mixture of hatchery and natural fish.
Freeze-brand data
from adult steelhead captured at Lower Granite Dam was provided by
National Marine Fisheries Service. The data that was compiled provided
insight to the potential rates of straying of Lyons Ferry stock steelhead
into the upper Snake River Basin. Also, freezebrand data on the Wallowa
Stock fish released from the Grande Ronde River at Cottonwood AP,
provided an estimate of adult returns to the project area, which have
generally been more reliable than coded-wire tag estimates.
Creel surveys
were conducted in all three run years, though data is only complete
for the 1998/1999 and 1999/2000 run years. Each year we surveyed about
6,000 steelhead anglers. Overall catch rates varied slightly between
the years. Estimates of angler effort, total harvest and tagged fish
harvested were summarized. We also cooperated with Oregon Department
of Fish and Wildlife (ODFW) to conduct creel surveys on the Lower
Grande Ronde River in Washington. Grande Ronde creel data (total catch,
effort hours, etc.) were summarized by ODFW and provided to WDFW for
inclusion into this report.
Based on harvest
estimates and returns to traps, we estimated total adult returns for
the 1995 to 1999 run years of steelhead from the LFC. Run years have
varied slightly, but most years have greatly exceeded the LSCRP goals
of 4,655 adult steelhead. Returns over the 5-year period have varied
between 114%-297% of the LSRCP steelhead mitigation goal established
for Washington.
Spawning ground
surveys were conducted in the Tucannon River, portions of the Touchet
River, and portions of the Asotin Creek basin for 1999, 2000, and
2001. River flows varied between years and made surveys difficult
in 2000. Estimated number of redds and spawners were derived for each
year.
Electrofishing
surveys on the Tucannon and Touchet rivers, and Asotin Creek were
conducted during July and August each year. Areas sampled and site
lengths were increased in 2000. Estimates provided are for the same
river reaches as in previous years. The numbers of naturally produced
steelhead in LSRCP rivers were similar to previous years and appear
to be generally stable.
In summary, the
Lyons Ferry summer steelhead program is meeting it’s original
mitigation goals by supplying above adequate returns for harvest within
the Lower Snake River area. However, impact to listed salmonid species
and other non-target taxa are probably not within acceptable levels.
Further evaluation and monitoring must occur to fully assess these
impacts. In the interim, new production goals for the Lyons Ferry
and Wallowa Stock program need to be established to reduce impacts.
