Colorado Pikeminnow
The Colorado pikeminnow is native to Colorado River basin’s larger rivers. Its current distribution has been severely reduced to the Upper Colorado River basin of Colorado, Utah, New Mexico, and Wyoming. It is one of the largest minnows in the world, historically reaching six feet and weighing over 100 pounds. It is top end carnivore and a voracious predator. Due to its size and migratory habits its common names included “white salmon.”
Adult pikeminnows prefer medium to large river habitats, including deep strong currents, eddies, runs, and backwaters. Young prefer small, quiet warm backwaters. Due to their migratory spawning, they also require uninterrupted passage.
Colorado pikeminnows are elongated with a pike-like profile. Their upper body is greenish in color with gold flecks and the underside is whitish. The head is long and slender sporting a large mouth bordered by thick. While the jaws are toothless, they have teeth located on the gills in the back of the throat that grasp their prey. During spawn the fins may be an orange hue. A long lived species it can live upwards of 40 years.
Once the river flows abate in summer, pikeminnow make their spawning runs. Distances over 200 miles have been documented. Spawning takes place over gravel riffles, where the eggs are randomly broadcast over the bottom and hatch within a week. The newly hatched larvae then drift down stream to slower moving backwaters. Colorado pikeminnow reach sexual maturity in five to seven years.
Young pikeminnows fed primarily on freshwater shrimp and midge larvae, shifting to insects as they grow. Ultimately they start feeding on fish, which becomes their primary diet as adults.
Colorado Pikeminnow in Colorado
Courtesy of Colorado Parks and Wildlife
Description: The Colorado pikeminnow, also known as the Colorado squawfish, is the largest North American minnow. These fish have been known to reach six feet in length and 80 pounds in weight. Adult fish may be green-gray to bronze on their backs and silver to white along their sides and bottoms. During spawning, their fins can take on an orange hue.
Range: Historically, the pikeminnow occurred in great numbers throughout the Colorado River system from Green River in Wyoming to the Gulf of California in Mexico. In Colorado, they are currently found in the Green, Yampa, White, Colorado, Gunnison, San Juan, and Dolores rivers.
Habitat: The Colorado pikeminnow thrives in swift flowing muddy rivers with quiet, warm backwaters.
Diet: Colorado pikeminnow are primarily piscivorous (fish-eaters), but smaller individuals also eat insects and other invertebrates.
Reproduction: The species spawns during the spring and summer over riffle areas with gravel or cobble substrate. Eggs are randomly splayed onto the bottom and usually hatch in less than one week.
Endangered status: The Colorado pikeminnow is listed as threatened in Colorado and endangered federally. Dam construction and other water diversion projects along the Colorado River system has contributed to its decline. Dams lower water temperatures and block migration routes, hampering spawning of pikeminnow. The introduction of non-native bait minnows and stocking of predatory game fish species (such as northern pike, largemouth bass, sunfish, and catfish) are suspected to have contributed to their decline as well. Recovery actions are underway to remove non-native fish, construct bypasses around in-stream barriers, and restock pikeminnow into native habitat.
