salmon smolts are not all equal, according to a recent study that examined the
same Hood River broodstock but reared a portion – a third – at each of three
different spring chinook hatcheries in the Columbia River basin before
releasing the smolts back into their native river.
hatchery stood out: the Pelton Ladder hatchery, operated by the Oregon
Department of Fish and Wildlife on the Deschutes River just downstream of
Portland General Electric’s Pelton-Round Butte Complex of dams. The hatchery is
funded by PGE and the Bonneville Power Administration.
Pelton Hatchery smolts migrated to Bonneville Dam and the Columbia River estuary
faster than the others and they came back in higher relative numbers (better
smolt-to-adult returns) than the other two hatcheries used in the experiment –
Parkdale Hatchery on the Hood River and the Carson National Fish Hatchery on
the Wind River in Washington.
Parkdale Hatchery is operated by the Confederated Tribes of the Warm Springs
and the Carson Hatchery is operated by the U.S. Fish and Wildlife Service and
is supported by Mitchell Act funds.
environments and different rearing protocols at different locations created
smolts that performed quite differently,” said Brian Beckman, a research
fisheries biologist with the Northwest Fisheries Science Center, NOAA
Fisheries, Seattle, and one of the study’s authors. “Smolt development, size at
release, speed of smolt out-migration, age of maturation and smolt to adult
survival varied widely among smolts of the same genetic stock reared under
different protocols in different hatchery environments but released at the same
place and experiencing the same out-migration gauntlet.
in hatchery rearing has profound abilities to influence post-release smolt
performance,” Beckman concluded.
Impact of Different Hatchery Rearing Environments on Smolt-to-Adult Survival of
Spring Chinook Salmon,” was published online March 30, 2017, in Transactions of
the American Fisheries Society (http://www.tandfonline.com/doi/abs/10.1080/00028487.2017.1281168?journalCode=utaf20).
authors are Beckman, Deborah Harstad, Dina Spangenberg, Rua Gerstenberger,
Chris Brun and Donald Larsen, all research fisheries biologists with the
Northwest Fisheries Science Center, NOAA Fisheries, Seattle.
rearing at Pelton Ladder and Carson, biologists brought the smolts back to
acclimation pens before releasing those smolts, plus the smolts reared at
Parkdale, into the Hood River. From 2010 to 2012 they released over 40,000
PIT-tagged spring chinook smolts into the river over the same three day period
average migration rate of the juveniles after release was 3.9 to 10 kilometers
per day (2.4 to 6.2 miles/day), but the migration rate for the Pelton fish was
significantly greater than that for either the Carson or the Parkdale fish.
“Rearing location was a significant predictor of migration rate to Bonneville
Dam, but BY (brood year) was not,” the study says. Migration rates to the
estuary had similar results.
its own, migration rate to Bonneville Dam was the best predictor of age 3-5
SAR,” the study concludes.
return, the smolt-to-adult return rate of the fish reared at the Pelton Ladder hatchery
was 1.55 percent, while the SAR from the Carson Hatchery was just 0.36 percent
and the SAR from the Parkdale Hatchery was 0.49 percent.
the proportion of fish that were two-year fish, or minijacks, was “highly
variable across brood years and rearing locations,” the study says.
results demonstrate the significant effect prelease rearing practices can have
on postrelease performance of spring Chinook Salmon smolts,” the study says.
from the Pelton Ladder hatchery were the largest at the time of release, had
the greatest degree of smolt development, the lowest loss as a result of early
male maturation (proportionally fewer minijacks, 2-year early maturing males)
and they returned in greater numbers as adults.
what is it about the Pelton Ladder hatchery that it would produce better
returning adults? The study says that the “overall rearing regime and growth
trajectory for fish reared at Pelton Ladder represents a template for producing
smolts with a combination of favorable smolt attributes.”
at the Pelton Ladder hatchery are actually reared in an abandoned fish ladder
below Pelton Dam, a facility, the study says, that would be “prohibitively
expensive to replicate elsewhere.”
difference between the hatcheries could be what the authors call the “wild fish
template.” It’s a phenomenon that is
similar to naturally-reared spring chinook in the Yakima River.
wild fish template is notable for the strong anabolic to catabolic shift in the
autumn that results in a cessation of growth and depletion in lipid stores through
the winter. In the early spring, there is another physiological shift, from the
winter catabolic phase to a spring anabolic phase, with the reinitiation of
growth,” the study says.
another study from the year 2000, Beckman suggested that the catabolic–anabolic
shift in the spring could be important for priming smolt development and be
related to the typically high smolt survival found in naturally-rearing fish.
2006, Larsen suggested that the summer–autumn shift from an anabolic state to a
catabolic state had important implications for modulating the stimulation of
male maturation that results in minijacks. Wild fish were found to undergo a
strong catabolic shift in the autumn and had a low rate of minijack production,
while hatchery fish maintained a positive anabolic phase through the autumn and
typically had enhanced levels of minijack production.
to Beckman, managers from the Confederated Tribes of the Warm Springs has since
the study changed their rearing protocols at the Parkdale Hatchery “to reduce
the abundance of early maturing males (age 2 minijacks) and increase the number
of full-size anadromous adults.”
he said, the wild fish template, although it provides a useful way to assess
hatchery fish development, is not a one size fits all route to better SARs and
selection has molded the physiological responses of juvenile salmon to
environmental variation to optimize smolt survival,” he said. So,
naturally-reared salmon from one river basin differ widely in traits from those
in another basin.
don’t think developing a single template for spring chinook salmon smolt
rearing across all populations and all rearing environments is possible”
because of the variations among populations and environments. “Our goal is to develop a mechanistic understanding
of how interactions among water temperature, feeding rate, photoperiod and
resulting growth rates influence age/size of smolting, smolt to adult survival
and age of maturation of chinook salmon smolts and thus help optimize smolt
rearing for different populations in differing hatchery environments.”
strategies for replicating the wild fish template, according to the study, are:
water temperature regimes to produce the anabolic-catabolic shifts seen in the
winter feeding regimes that include weeks to months of fasting.
changes can be made without expensive facility changes, the study concludes.
of the biggest implications of our study is that the choices managers make
about such things as seasonal growth rates (feeding rates) may have large
impacts on subsequent smolt performance,” Beckman said. “Our goal is to help
managers understand the implications of some of the rearing choices they have
additional information from NOAA Fisheries about this study, see a feature
story by Al Brown at https://www.nwfsc.noaa.gov/news/features/wild_fish_template/index.cfm