Trout Spawn is Wrapping Up
Posted: 01/25/2011

Fresh snow, temperatures in the single digits... and two men standing in water up to their waists. The chest waders and arm-length gloves make it tolerable. But for Dave Marolf and Randy Mack, it is just another winter day during the trout spawn at the Department of Natural Resources' Manchester hatchery.

Crews stock trout from April through November, on 50 or so northeast Iowa streams. From late fall to midwinter, though, they concentrate on future fishing. Big brood trout; brooks, browns and rainbows get a heavy dose of the 'human touch' to vastly increase survival of eggs and just-hatched fish. "We produce about 300,000 rainbow trout here; about 85 percent of the catchable fish we stock," says hatchery manager Marolf. "The other 15 percent are native brook trout; eggs stripped from wild fish on the stream bank."

By the end of January, workers are hoisting the last of the five to 10 pound rainbow brood trout from outdoor raceways. Each trout belly is lightly stroked. If a few eggs trickle out, the fish is 'ripe' and is plopped into the pull-behind tank, for a ride inside.

In the hatchery, the trout go into holding tanks on one side of the incubator room. On the other, is a wall of incubator trays. "When the fish are ready to spawn, we put them into an anesthetic bath to sedate them. Then, we can handle them without injury and strip the eggs in a few minutes," explains Marolf.

Each female yields a couple thousand bright yellow-orange eggs. Sperm from the on-site stock of males is added, along with a saline solution. The mixture is stirred gently for 30 seconds with a turkey feather to facilitate fertilization. Poured carefully into the trays, the fertilized eggs now sit under constant, 50 degree water flow.

In 30 days, tiny sac-fry hatch. Even then, the work is just beginning. The brook and brown trout have hatched already; even some of the earliest rainbow eggs. Dark clouds of tiny fish grow in raceways within the hatchery. Still, it will be 2012 before Iowa's 36,000 trout anglers see this spawning 'class' chasing their flies, salmon eggs, redworms or chunks of cheese.

Brown trout will be turned loose this spring, as two-inchers. After years of improvements in stream quality and reproduction, Iowa brown trout grow to maturity in the wild. Rainbows and brook trout still need a guiding hand back at the ranch. That extra year of work, feed and effort is financed by the $13 trout fee each trout angler pays, in addition to any regular fishing license charge.

It also pushes hatchery workers to work efficiently. In past years, a time-consuming tradition was to pull up a wooden stool, grab a turkey baster and siphon dead eggs from those incubator trays. "Now, we use an 'electronic egg picking machine.' It identifies the dead eggs through a photo detector process," says Marolf. "As hundreds of eggs per minute cycle through, microscopic puffs of air blow dead ones out of the wheel. Our labor costs have gone down immensely with that."

These coldwater fish are great fighters....and as a trout angler you can choose to chase wild browns or brooks in the far back reaches of walk in streams...or greet the stocking truck at the easier to reach put-and-take streams a couple times a week. The common denominator is that these sleek, hard fighting trout have a human helping hand involved in every stage from spawning to catching them.