Fall spawning: Story Fish Hatchery creates conditions ideal for trout eggs to thrive

BUFFALO - If you've caught a trout in Wyoming, chances are it grew from an egg spawned at Story Fish Hatchery.

Operated by the Wyoming Game and Fish Department, the hatchery located just over the border from Johnson County is the state's primary source of trout eggs, which eventually grow to live in lakes for anglers to catch. 

October at the fish hatchery is reserved for spawning five varieties of trout: brown, brook, lake, splake and tiger. 

The role of fish hatcheries is twofold, according to Steve Diekema, superintendent of the Story hatchery. First, these facilities exist to raise fish to stock public waters, specifically those that are man-made, which means fish cannot naturally live and reproduce there. 

Hatcheries also exist to protect native species. 

If a population of fish is at risk for any reason, Diekema said, hatcheries are a genetic repository. 

As fish hatcheries go, Story's is unique. Not only is it the only facility in the nation that raises genetically pure golden trout, but it's also Wyoming's source for trout eggs. 

"It has to do with our water temperature," Diekema said. 

The facility's water flows from South Piney Creek, meaning that the temperature is dependent on the air temperature. So in the winter months, it's cold, typically around 36 degrees; then it warms up starting in May, peaking in August at around 56 degrees.

Trout grow faster in warm temperatures and more slowly in cool temperatures.

"We're keeping them in their natural environment with natural daylight, for the most part," Diekema said. "We try to keep things lit so they get that photo-period as well. That really helps us with our adults and why they produce high-quality eggs." 

Other facilities, Diekema said, get their water from a spring source, meaning that it stays warm year-round. That's why Story ships its eggs to other hatcheries, whose staff then raise them into the fish that get stocked in lakes throughout Wyoming.

A healthy population of fish hinges on genetic diversity, Diekema said. To ensure that fish can withstand disease, climate and other stresses, fish culturists at the hatchery make sure fish that are going to spawn are not siblings from the same stock. 

With brown trout that Game and Fish employees spawned on Oct. 5, they used 5-year-old females and 4-year-old males. 

In spawning, female fish lay eggs while the male fish fertilizes them with milt, or sperm. At the hatchery, staff members net the fish that are ready to spawn and place them into a tub of anesthetic, which makes them fall asleep. This not only makes it easier for the employees to grab them and extract eggs and sperm, but it also reduces stress on the fish, Diekema said. 

Once the fish roll over, signaling that they're sufficiently incapacitated, gloved Game and Fish staffers pick a female out of the tub and squeeze down her belly until bright orange eggs are released from her urogential opening into a pan. 

From there, a male is squeezed in the same way releasing its sperm into the same pan to fertilize the eggs. 

Unlike other fish species, trout survive after spawning and continue to live at the hatchery. 

The eggs and sperm are mixed together and cleaned with water to filter out any dead eggs (identifiable by their white color), feces or other bacteria to keep fungus from growing once the eggs reach incubation. 

These just-fertilized eggs then sit in a cooler for an hour until their shells harden, at which point they move into the facility's incubators.

Part of Story Fish Hatchery's success in spawning trout is its ability to mimic natural conditions for those fish that aren't able to reproduce in man-made water bodies abundant in Wyoming. This comes into play not only during the spawning stage but also during the incubation stage. 

In a room separate from the pools of adult fish, eggs are incubated, which is the process of bringing them to hatching. The science behind why this works is complicated, but Diekema, accustomed to hosting school groups and other curious visitors, is able to explain it at an approximately fifth grade level. 

An egg before the incubation stage is called a green egg, despite its orange hue. How the facility incubates its eggs depends on what other hatcheries around the state and country are requesting, Diekema said. The process hinges on one fact: fish are coldblooded. 

Because of this, their internal temperature matches their environment. A fish's metabolism speeds up in warmer water, which means it can process food faster and, essentially, grow faster, whereas cold temperatures slow the growth process.

Diekema said that fish culturists at the hatchery can vary the water temperature to time egg development, thereby ensuring that the hatchery can deliver eggs at the right state of development on a specified date. 

"That's really all we're doing, but it's a big part of the fish culture process," he said. "Without these eggs, there wouldn't be fish. By making sure we can provide them eggs at the right time, it allows our hatchery systems to be efficient. Then they can stock out the fish at the time the managers want at the size that the managers want them."

On average, these eggs have an 85% to 90% survival rate, Diekema said. 

Once they're incubated, the facility sorts out dead eggs and prepares to pack viable eggs, identifiable by their developing eyes that resemble two black dots on the orange sphere, into tubes that will be packed in coolers for shipping to their new home at a hatchery somewhere else. 

While these destinations are mostly in Wyoming, Game and Fish trades species raised in Wyoming for those that aren't, such as catfish, walleye, tiger muskie and bass. The Story Hatchery will ship eggs to four states this fall, including Idaho, Nebraska, Colorado and Oregon.

In total, the fall spawning operation will produce roughly 3.5 million eggs, according to Game and Fish.

Not only does the Story Fish Hatchery produce the tangible product of future fish for anglers to enjoy, but it is also the state's most visited hatchery. 

Diekema said it typically records 20,000 visitors annually. And it's a site that the community takes pride in.

"It's been a good relationship here," he said. "The community takes some ownership, and we enjoy being part of this. I mean, 1909, it's been, from day one, really with this community."