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Earth Notes: Colorado Pikeminnow

Colorado pikeminnow
Utah Division of Wildlife Resources
Colorado pikeminnow

A minnow that can reach six feet long and weigh eighty pounds—now that’s a fish story! But, this one happens to be true. The Colorado pikeminnow was known to reach such sizes. This impressive native species, long endangered, may again inhabit some of its historic range if recovery efforts succeed.

The pikeminnow once lived throughout the Colorado River Basin, including the Green, San Juan, and other tributaries. It does best in 65 to 85-degree water. It also needs high flows in the spring to create clean cobble bars for spawning; adequate water for incubating eggs and transporting larvae; and long uninterrupted stretches of river.

Those connected river reaches are critical because pikeminnows migrate hundreds of miles to spawn. Over the last century dams and water diversions have physically blocked their upstream movement. Dams also release colder water, hold back floods, and reduce the quiet backwaters needed for nurseries.

Pikeminnows are top predators and eat only other fish. Still, the young can’t compete against nonnatives such as smallmouth bass and walleye.

Wild pikeminnow populations exist in a few places in the upper basin. But in Grand Canyon, between Glen Canyon and Hoover dams, they’ve been absent for fifty years. The last one was caught near Havasu Creek in 1972.

Researchers want to reintroduce the species in the western Canyon where the river is warmer. Ironically, dams may make this more feasible now because of lower reservoir levels and warmer water releases. Whether this native fish can make a comeback remains to be seen—but some biologists are optimistic.

This Earth Note was written by Rose Houk and produced by KNAU and the Sustainable Communities Program at Northern Arizona University.

Rose Houk is a Flagstaff-based writer and editor, specializing in natural history and environmental topics.  Rose was a founding contributor of KNAU's Earth Notes and has written nearly 200 scripts for the series. She is also the author of many publications about national park and monuments, along with audio productions. 

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