Lyons Ferry Hatchery
(LFH) and Tucannon Fish Hatchery (TFH) were built/modified under the
Lower Snake River Fish and Wildlife Compensation Plan. One objective
was to compensate for
the estimated annual loss of 1,152-spring Chinook (Tucannon River
stock) caused by
hydroelectric projects on the Snake River. The standard supplementation
production goal is
132,000 fish for release as yearlings at 30 g/fish (15 fish per pound).
The captive brood
production goal is 150,000 yearlings at 30 g/fish. This report summarizes
activities of the
Washington Department of Fish and Wildlife Lower Snake River Hatchery
Evaluation Program
for Tucannon River spring Chinook for the period April 2005 to April
2006.
Two hundred forty-five
salmon were captured in the TFH trap in 2005 (125 natural adults,
6
natural jacks, 94 hatchery adults, and 20 hatchery jacks); 100 were
collected and hauled to LFH
for broodstock and the remaining fish were passed upstream. During
2005, five salmon that
were collected for broodstock died. Prespawning mortality has been
low since broodstock began
being held at LFH in 1992, and is generally less than 10% each year.
Spawning of supplementation
fish in 2005 at LFH occurred between August 23 and September
20, with peak eggtake on September 6. A total of 161,345 eggs were
collected from 25 natural
and 24 hatchery-origin fish. Egg mortality to eye-up was 3.2% (5,239
eggs), with an additional
loss of 10,827 (6.9%) sac-fry. Total fry ponded for production in
the rearing ponds was 145,279.
A total of 167
captive brood females were spawned from August 31 to October 11, 2005
producing 261,845 eggs. Egg mortality to eye-up was 60.4% leaving
103,812 live eggs. An
additional 9,841 dead eggs/fry (9.5%) were picked at ponding leaving
93,971 fish for rearing.
WDFW staff conducted
spawning ground surveys in the Tucannon River between August 31 and
September 29, 2005. Forty-six redds and 22 carcasses were found above
the adult trap and 56
redds and 29 carcasses were found below the trap. Based on redd counts,
broodstock collection, and in-river pre-spawning mortalities, the
estimated escapement for 2005 was 420 fish (286 natural adults, 3
natural jacks and 123 hatchery-origin adults, 8 hatchery jacks).
Snorkel surveys
were conducted during the summer of 2005 to determine the population
of
subyearling and yearling spring Chinook in the Tucannon River. We
estimated 30,809
subyearlings (BY 2004) and 586 yearlings (BY 2003) were present in
the river. Evaluation staff
also operated a downstream migrant trap. During the 2004/2005 emigration,
we estimated that
23,003 (BY 2003) natural spring Chinook smolts emigrated from the
Tucannon River.
Monitoring survival
rate differences between natural and hatchery-reared salmon continues.
Smolt-to-adult return rates (SAR) for natural salmon consistently
average about five times higher
than for hatchery salmon. However, hatchery salmon survive about three
times greater than
natural salmon from parent to adult progeny. Due to the low SAR for
hatchery fish, the
mitigation goal of 1,152 salmon of Tucannon River stock was not achieved
as only 131 hatchery origin fish returned in 2005. Beginning with
the 2006 brood year, the annual smolt goal will be
increased from 132,000 to 225,000 to help offset for the higher mortality
of hatchery-origin fish
after they leave the hatchery. In conjunction with this we also plan
to conduct an experiment to
examine size at release as a possible means to improve SAR of hatchery
fish.
