Education
- Let's Go Outside!
The
Hatchery's Role in Restoring Fish Populations
SIMULATING
A NATURAL ENVIRONMENT - SALMON
RETURN - SPAWNING - INCUBATION - NURSERY
TANKS - OUTDOOR RACEWAYS - SMOLT
RELEASE
The Confederated Tribes of the Warm Springs realized long
ago the need to restore the fishery resource, not only for
the benefit of Indians, but for everyone. The Warm Springs
National Fish Hatchery was started as a cooperative effort
to make more fish available on the Columbia, Deschutes, and
Warm Springs rivers. Each year young Chinook salmon are
released into the Warm Springs River to replenish and restore
fish populations.
The hatchery provides a safe environment for the development
of eggs, fry, and fingerlings. Controlled conditions allow
the hatchery staff to mimic growing conditions of wild fish.
In the past attempts were made to rear the fish as large as
possible but there was a concern that this approach may create
a competitive advantage over wild fish. This practice is no
long employed.
The hatchery simulates the salmon's natural growing environment
by providing clean, cold, water. Fresh river water enters
the hatchery and is filtered before being pumped to the various
tanks and ponds. Large debris, such as leaves and twigs,
are removed by a series of grids and screens. Smaller debris
is removed in sand filters, and harmful bacteria and other
organics are killed as the water passes through ultraviolet
lights.
Salmon rearing begins with adult spring Chinook returning
upstream from April through August. The hatchery barrier
dam requires all fish to climb the fish ladders into the hatchery,
where wild and hatchery fish are separated. Wild fish
are released above the hatchery barrier, while hatchery fish,
identified by tags, remain in holding ponds until ready to
spawn. Holding ponds are kept at 50º F, since warm
water causes the fish to spawn too soon. Because river
temperatures rise above 60º F in the summer, chillers
cool the water before it is pumped to the holding ponds.
Spawning begins in August and continues weekly through September. The
broodstock - adult fish used for spawning - in the holding
ponds are moved to the spawning area where hatchery biologists
remove eggs from the females and fertilize them with milt from
the males. To gather enough eggs to restock the river at optimum
level, up to 700 adult fish are needed for spawning. When
available, 10 percent of the wild salmon coming through the
hatchery are added to the hatchery boodstock to retain genetic
traits.
The fertilized eggs are poured into incubation
trays. Clean, cold, oxygen-rich water is pumped through
the tray stack, which holds 6,250 eggs per tray. Optimum
water temperature for proper growth at this stage is 50º F. Winter
river temperatures drop to freezing, so water is heated by
boilers before being pumped through the trays. By late
October eyes of the developing embryos can be seen through
the egg shells, and in late December and January eggs hatch
into sac fry
In December and January fry are transferred to nursery tanks
and fed a prepared diet high in fish protein. The hatchery
water is warmed to increase feeding activity and speed up the
growth process.
By March, fry develop into fingerlings and are put into the
outdoor raceways after being acclimated to cooler outside temperatures. In
April and May, hatchery fingerlings are tagged with a coded
wire tag in the snout and an adipose fin clip to distinguish
them from wild fish. Most young salmon stay in the raceways
to develop until the following spring, although some early
developers are ready to migrate in the fall.
Spring
Chinook salmon fingerlings being fed by Kevin Blueback,
Fish Culturist
At about 16 months of age, fingerlings have developed into
smolts and are ready for migration. Each year approximately
750,000 smolts are released into the Warm Springs River and
join wild smolts on their journey to the Pacific Ocean, where
they will feed and grow for 1 to 4 years before making their
return to the Warm Springs River to spawn, continuing the salmon's
life cycle. 
|
