Home from the sea
Sawtooth Hatchery helps sustain steelhead fishery
By GREG STAHL
Express Staff Writer
The Idaho Department of Fish and Game’s Sawtooth
Hatchery is the farthest anadromous fish hatchery from the Pacific Ocean,
but that hasn’t kept some 2,500 adult steelhead from completing the
900-mile journey home this spring to the Salmon River headwaters in the
shadows of the Sawtooth Mountains.
Last week, between Monday and Thursday, 445 steelhead swam
into fish traps at the hatchery’s weir on the river, just a couple of
miles south of Stanley. Each Monday and Thursday, through the first week
in May, steelhead trapped at the weir will be stripped of their eggs and
sperm as part of an artificial fertilization operation. Their progeny,
raised in various hatcheries over the winter, are then brought back for a
downstream rollercoaster ride to the Pacific Ocean next spring.
Steelhead are an anadromous breed of rainbow trout. That
means, like salmon, they spawn in freshwater streams but live most of
their lives in the ocean.
The 445 fish captured last week were hatchery-raised. But
historically, thousands upon thousands of wild steelhead returned to the
Stanley Basin each year, said Fish and Game fisheries biologist Charlie
Petrosky. Now very few of the upper Salmon River’s wild steelhead
remain, with only 15 wild fish captured so far this year at the hatchery.
Idaho’s steelhead have been listed as a threatened
species under the Endangered Species Act. Idaho’s chinook and sockeye
salmon are listed as endangered species—a more critical category.
Fish and Game’s steelhead hatchery program is intended
to maintain populations for sport fishing, said Sawtooth Hatchery manager
Brent Snider. Chinook and sockeye salmon hatchery programs, he pointed out
for comparison, are conservation-oriented, meaning the salmon populations
are in greater danger of becoming extinct. They are no longer fished
unless, like this year, there is an exceptional abundance of hatchery fish
in the returning spawning run.
Breeding and raising fish is a fairly lengthy and
complicated process. But nearly each step of the process was evident
Thursday in the operations occurring at the Sawtooth Hatchery.
When fish reach the hatchery’s weir, which prevents any
further upstream migration, they instinctively swim upstream and climb a
fish ladder, entering a holding pond. Snider pointed out that fish are
later sorted by sex in preparation for the artificial fertilization that
occurs each Monday and Thursday during the season.
It’s a process hatchery personnel call
"moving" fish.
Moving fish consists of collecting eggs and sperm,
fertilizing the eggs, placing them in incubation trays and raising them to
the size when they can be transferred to rearing ponds to complete their
growth to the smolt stage. The smolts¾ which have to be old enough to
make a physiological transformation from freshwater fish to saltwater fish
to survive in the ocean¾ are then returned to the Salmon to renew the
cycle of steelhead going to the Pacific.
Between incubation and the age of 11 months, the Sawtooth
Hatchery’s steelheaed are raised in separate hatcheries, though the
majority are taken to the Hagerman Hatchery in the Thousand Springs
Valley.
About a dozen College of Southern Idaho (CSI) aquaculture
students and Sawtooth Hatchery personnel worked Thursday to move all 445
fish that had entered the traps during the previous three days.
Additionally, 11-month-old steelhead smolts were returned to the hatchery
by truck from the Hagerman Hatchery for this spring’s releases into the
river.
The adult steelhead are killed during the fertilization
process.
"If we were in conservation mode, we could attempt to
keep them alive," Snider said. "We could turn them back out to
the river, but they’d probably all die."
Steelhead, unlike salmon, don’t die after spawning. But
the 900 miles between the Pacific and the upper Salmon steelhead spawning
habitat make multiple spawning trips unlikely, Snider said.
Females are cut open, their eggs removed and placed into
buckets. To get sperm from the males, fish abdomens are massaged, and
sperm squirts into a cup.
CSI assistant hatchery manager Steve Rivas said the
killing of adult fish is the primary difference between fertilizing
steelhead eggs and rainbow trout eggs, with which his students have
received most of their instruction.
The steelhead returning to central Idaho this spring
entered the Columbia River last summer or fall. The fish winter in the
river system, usually downstream from the city of Salmon.
Rainbow trout, because they live in local streams, are
spared during hatchery operations, Rivas said. They live to breed or spawn
again.
Fertilization of steelhead eggs occurs when sperm is added
to a bucket of eggs and mixed, an act that amounts to adding a smidgen of
milk to a bucket full of soft beads. Fertilization only takes about 15
seconds, Snider said. The eggs are then put into well water, which helps
them harden. Iodine is added to kill any impurities or parasites.
Fertilized eggs are put in incubation trays, which
maintain a constant temperature and circulate oxygen to the soon-to-be
fish. The hatchery has thousands of trays, and each female’s eggs are
incubated separately.
After about 45 days in the incubation trays, eggs reach
what is called the "eyed stage," which means the egg contains an
embryo that has developed enough so the eyes are visible through the egg
membrane.
Snider said the hatchery boasts 93 percent survival rates
to the eyed stage and 83 percent survival rates to one year of age.
"Naturally, survival rates (in the wild) are in the
single digits," he said.
At the eyed stage, eggs become less delicate and are moved
to other hatcheries where the young steelhead are raised to the smolt
stage.
However, in the Sawtooth Hatchery’s salmon the young
salmon never leave the hatchery. They’re raised there until it’s time
to return them to the wild, free-flowing Salmon River.
The hatchery has 14 outdoor raceways, where the smolts are
held until the time of their release. Last Wednesday, about 57,134 Chinook
salmon smolts were released from two raceways to begin their downstream
migration. They’re fish that have spent 20 months at the hatchery.
On Thursday, one-year-old steelhead were returning to the
Sawtooth Valley from Hagerman and put into raceways to "imprint"
on and adjust to the frigid water of the Salmon.
Three tanker trucks, holding 20,000 fish each, emptied
their contents into a raceway. Each raceway generally holds about 60,000
fish.
The approximately 6-inch-long smolts will be held there
until Thursday or Friday of this week, when they’ll be returned to the
Salmon.
Unfortunately, Fish and Game personnel aren’t expecting
a booming return from out-migrating fish this spring, primarily due to low
water levels.
Fisheries biologist Petrosky said out-migrating smolts
depend largely on river currents to make it to the ocean. Smolts
downstream and face upstream, into the flow, as the current rushes them to
the ocean.
Without much runoff predicted this spring, slack water in
the Lower Snake and Columbia River dams could impede the migrating smolts’
journey to the sea.
