Hundreds
of yellow ovals offset the brown and green coloration of each female brown trout
ready to spawn at the Manchester Fish Hatchery. The splashes of color are signs
that trout spawning season is in full swing.
Brook trout, Iowa’s only native trout, already
gave up their eggs in October. A
domesticated strain of brook trout is maintained at the Manchester Fish
Hatchery. Over 453,000 eggs were collected this year.
Brown trout are currently being spawned.
Brood trout are brought to the hatchery from French Creek in Allamakee County. They
are held at the hatchery across two spawning cycles then released in several
dozen stretches of streams throughout northeast Iowa, supplementing earlier
generations of brown trout.
All
brown trout are stocked as 2-inch fingerlings. “Anglers like these ‘wild’
stream raised fish. They are harder to catch than our put-and-take stocked fish,”
explains Mike Steuck, Iowa DNR fisheries supervisor for interior streams. “Many
of the public streams have great numbers of brown trout in them.”
Rainbow trout, the backbone of Iowa’s trout
program, take up much of December and January. Roughly 750,000 eggs will be
collected this season.
Once a
week, crews check for ripe female brood stock. After a quick sedative bath to
quiet them, each big trout is held firmly over a plastic bowl, as one of the
workers rolls a hand down her belly to force out a stream of orange-golden eggs—up
to 4,000 to 6,000 per fish. Mixed in quickly is the milk-white sperm from two
males. Water is added to activate the eggs and sperm allowing fertilization to
occur. The ingredients are gently stirred with a turkey feather to avoid
bruising the eggs.
The fertilized
eggs are poured into an incubator tray and slid into their place below a stream
of 50 to 52 degree water until they hatch. Approximately 30 days after
fertilization, tiny sac-fry hatch. Dark clouds of tiny fish grow in raceways
within the hatchery. The fish are “trained” by automatic feeders to eat.
As
they develop and grow, they are monitored and transferred to larger tanks, then
raceways. The fingerlings will be kept
at Manchester or transferred to Iowa’s two other stations, near Elkader and
Decorah, to be raised for future stocking. In 12 to 14 months, they will be a
half-pound and ready to be stocked. Nearly
50 put-and-take streams throughout nine northeast Iowa counties and nearly 20
urban locations are stocked through the cold weather months.
“We stock
about 400,000 catchable rainbow trout at the hatcheries,” said Steuck. “We also stock approximately 200,000 brown and
rainbow trout fingerlings annually to grow in the streams.”
There’s
natural spawning, mostly brown trout and some brook trout, in over 40 northeast
Iowa streams. Most trout caught, though, are spawned under the eyes of hatchery
workers at Manchester. These coldwater fish are great fighters and beautiful in
their spawning colors this time of year.
