Colorado Pikeminnow, formerly known as Colorado Squawfish, are extinct in California and absent from the lower Colorado River drainage which they historically occupied. They are listed federally and in California as an endangered species and are only found in small numbers in the upper mainstem Colorado River and tributaries such as the Green River, Yampa River, and San Juan River. Juvenile Colorado Pikeminnow live in shallow edge habitat and backwaters. They feed on aquatic invertebrates, and shift to feeding on fish as they reach 100 mm TL. Larger fish may move actively through the river, but still tend to inhabit backwaters and areas with slower currents and abundant prey. Colorado Pikeminnow mature after age 6, at 430-500 mm TL, and may live to 30 years. They may make long spawning migrations of over 200 km, starting in early summer. They spawn in late June to early August in fast-flowing rapids in deep canyons where the eggs stick to the gravel substrate. Eggs hatch in 3-6 days and larvae drift downstream over 100 km to rearing habitat.
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