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Idaho’s Rainbow Trout Capital

There are few moments in an angler’s life that rival catching their first rainbow trout, and whether you caught it on a hare’s-ear fly or a nightcrawler, chances are good there’s a special place in your memory for the first time you hooked one of Idaho’s most precious fish.

The story of a hatchery trout’s journey from egg to angler is just as captivating. For wild rainbow trout, a cool, clear river may have been its home since it hatched from a little ruby-colored egg. But for many Idaho rainbows, their life began at Idaho Fish and Game’s Hayspur State Fish Hatchery.

Idaho’s First Hatchery

Hayspur State Fish Hatchery, located 30 miles south of Ketchum, became Idaho’s first hatchery in 1907. It began as wooden raceways built directly into the creek bed, and over the last century it has evolved into a modern facility pioneering new incubation and spawning technology, which has made it the state’s most productive rainbow trout source.

Today, Hayspur includes a variety of buildings that allow managers to spawn trout year round, provide eggs for other hatcheries, as well as grow trout to be released in nearby waters.

Gregg Anderson has been involved with Hayspur State Hatchery since 2015. As overseer of millions of juvenile trout, Anderson has been integral in developing a specialized spawning process unique to Idaho.

“Hayspur is a demanding and challenging fish production facility, however it also is a very rewarding facility,” Anderson said. “At the end of the day, you have a sense of accomplishment and feel your efforts have made a significant contribution to making fishing better in Idaho.”

Shedding Light on Trout Spawning

In the wild, rainbow trout spawn once per year during spring, which is triggered by longer days with more sunlight as the fish come out of winter.

Biologists have studied these patterns and learned that by mimicking the length of light that fish grow in, they are able to essentially “trick” rainbow and brook trout into spawning at various times of the year in a process called “photo period manipulation.”

Fish Hatchery Manager Tom Lindenmuth, who’s been a part of the Hayspur Hatchery team since 2015, says there are several advantages that make Hayspur’s photo period manipulation process unique.

“At Hayspur, we are able to get two egg takes per year thanks to strategic light manipulation,” Lindenmuth said.

The hatchery contains 15 grain silo-like circular ponds that house around 500 females and 250 males in each one. The ponds resemble metal yurts, with pitched roofs and a single lightbulb as the light source.

Biologists carefully alter the duration of light – from 6 to 18 hours a day depending on the spawning cycle – to trigger the fish to spawn. Each circular pond is on a six-month cycle, allowing fish in a particular pond to spawn while others are in waiting.

“Another benefit of photo period manipulation and year-round spawning is helping out other regional hatcheries and being able to provide eggs when it’s ideal for that facility to receive them,” Lindenmuth said. “Hayspur can spawn trout and have fertilized eggs out the door in 18 days.”

Lindenmuth and his team typically spawn batches of trout twice a week, depending on factors like time of year and demand. When the trout are ready to spawn, it’s all hands on deck.

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