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Utah’s 90-Pound “Minnow”

When most people hear the word “minnow,” they probably think of tiny baitfish, but the Colorado pikeminnow is anything but tiny. It is the largest minnow in North America and is only found in the Colorado River Basin — nowhere else in the world.

In the early 1900s, the Colorado pikeminnow was a popular target for those who fished the Colorado River and its many tributaries. The big, aggressive fish put up a fight and were easy to catch on a variety of baits and lures.

The following stories, shared in the report Historical accounts of upper Colorado River Basin endangered fish, identified mice, frogs, baby swallows, cottontail rabbit heads, chicken parts and other fish as some of the best baits for Colorado pikeminnows.

Steve Radosevich, a retired Utah conservation officer from Browns Park, once reminisced about his brother-in-law catching a 23-pound Colorado pikeminnow with a mouse. “I heard stories about that, he went fishing with a mouse,” Radosevich said. “Mouse was on the hook when he put it on the board, shoved it out in the river, was trolling back with it when the big fish got it.”

Bill Allen of Vernal, Utah fished the Green River in the early 1930s and recalled a memorable trip, “I used a half a cottontail rabbit head on one line and a chunk of breakfast bacon about that square on the other line. I caught a 15-pound [pikeminnow] and a 20-pound [pikeminnow] right down by the Swinging Bridge…”

Tim Merchant, of Green River, Wyoming, recalled fishing for pikeminnow with his grandfather in a section of the Green River now covered by Flaming Gorge Reservoir. “They’d called it Linwood; it’s under water now, and we’d picnic down there, spend the day,” Merchant said. “And my grandfather would get chicken parts, just great big old chunks of chicken parts and stuff like that, put a hook in it and throw it out into the river into those big holes down there with clothes line. He just tied clothes line on it onto the bumper of the truck. And when that went tight they’d just back the truck up and drag those fish out on the bank. I can remember twice, two separate occasions dragging those [pikeminnow] out with the truck. They was as big as a junior high school kid, 90 pounds. That’s a big fish,” he said.

Dale and Max Stewart grew up in Vernal, Utah in the 1930s and both had memorable catches of Colorado pikeminnow that weighed at least 25 pounds. The Stewart brothers also had fond memories of eating the large fish. Dale noted, “…you can see how you can cut steaks off that thing. I remember a fish like that really was a harvest, and it produced not just one meal, but quite a few meals for the family.”

Back in the early 1800s, the pikeminnow grew to more than 5 feet long and easily swam throughout the warm-water reaches of the basin. Now, both the species and its range are somewhat smaller in size.

Today’s adult pikeminnows grow more than 3 feet long, and their range has fragmented with increased human use of the river basin. This fragmentation — along with habitat changes and the spread of predatory, nonnative fish species — prevent the pikeminnows from traveling as widely as they did in decades past.

Despite their size, Colorado pikeminnows are still similar to other members of the minnow family in many ways — they are all toothless, for example. But a lack of teeth doesn’t stop the pikeminnow from pursuing and eating large prey. Pikeminnows are impressive predators and voracious eaters. They primarily feed on fish but will sometimes eat other small animals when the opportunity arises.

Because they evolved in a large river basin — one that used to flow freely from Wyoming to the Gulf of California — Colorado pikeminnows migrate long distances to reach their white-water canyon spawning areas. Some of their journeys are more than 200 miles!

Many people know that lake trout can live for 50 years, but they’re surprised to hear that Colorado pikeminnows can live just as long! This isn’t the norm for freshwater fish — most live less than 10 years. This impressive life span allows the pikeminnow to reach its exceptional size, and also ensures that adults have multiple chances to reproduce successfully.

During the summer, adult pikeminnows gather on shallow gravel bars to spawn. Females deposit eggs on the river bottom, and then males fertilize the eggs. Some of the locations where they spawn include:

  • Yampa Canyon
  • Desolation and Gray canyons on the Green River
  • Gunnison River
  • Colorado River
  • San Juan River
  • White River

When the eggs hatch, tiny pikeminnow larvae drift downstream with the river current — they begin their lives with a natural, downstream migration! It’s a journey that takes them great distances to find suitable places to grow. Sometimes they drift for more than 80 miles before finding the backwaters that will serve as a nursery habitat.

Backwaters provide important nursery areas for juvenile pikeminnows after their downstream migration as drifting larvae. Built by spring floods — and then maintained by adequate flows through the hot summer months — these pockets of relatively warm, calm water serve as a critical refuge for small pikeminnows in their first few months of life. Many wild river reaches in Utah provide this habitat type for young pikeminnows:

  • Uintah Basin section of the Green River
  • Labyrinth and Stillwater canyons on the Green River
  • Colorado River, above the confluence with the Green
  • San Juan River

Colorado pikeminnows not only use large rivers as migration corridors, but they also use smaller tributaries. Some of these include McElmo Creek and the Price, San Rafael and White rivers.

The nearly constant movement and migration of pikeminnows demonstrate the species’ need to move freely throughout the river basin. To help these unique fish access the diverse habitats needed to complete their life cycle, fish-passage structures have been built at sites where human water use and fish needs may otherwise be in conflict. These structures allow the pikeminnows to successfully navigate barriers and complete their migration.

The information presented in this story represents the hard work of many researchers and managers — and shares the inspiring journeys of these remarkable fish. Many of the individual pikeminnow stories come from passive integrated transponder (PIT) tags implanted in wild fish during studies. When we capture the fish during annual surveys — or detect them during routine monitoring — we can identify individual fish through their PIT tag codes. Every contact provides important data points about where these fish have traveled and how their populations move and survive in the Colorado River Basin.

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