| Colorado pikeminnow | |
|---|---|
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Cypriniformes |
| Family: | Cyprinidae |
| Genus: | Ptychocheilus |
| Species: | P. lucius |
| Binomial name | |
| Ptychocheilus lucius Girard, 1856 |
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The Colorado pikeminnow (formerly squawfish) Ptychocheilus lucius is the largest cyprinid fish of North America and one of the largest in the world, with reports of individuals up to 6 ft (1.8 m) long and weighing over 100 pounds (45 kg). Native to the Colorado River basin of the southwestern United States, it was formerly an important food fish for both Native Americans and European settlers. Once abundant and widespread in the basin, its numbers and range have declined to the point where it has been listed as endangered (1967), a fate shared by the three other large Colorado basin endemic fish species: Bonytail chub, Humpback chub, and Razorback sucker.
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Like the other three species of pikeminnow, it has an elongated body reminiscent of the pike. The cone-shaped and somewhat flattened head is elongated, forming nearly a quarter of the body length. Color grades from bright olive green on the back to a paler yellowish shade on the flanks, to white underneath. Young fish also have a dark spot on the caudal fin. Both the dorsal and anal fins typically have nine rays. The pharyngeal teeth are long and hooked.
The reports of 6 ft individuals are estimates from skeletal remains but a number of community elders, interviewed by the Salt Lake Tribune in 1994, reported that such individuals were once common. Catches in the 1960s ranged up to 60 cm for 11 year old fish but, by the early 1990s, maximum sizes reached no more than 34 cm. Biologists now consider the average size of an adult pikeminnow to be between 4 and 9 pounds, and reports of the fish latterly exceeding 3 feet in length are now in question.
Young pikeminnows, up to 5 cm long, eat cladocerans, copepods, and chironomid larvae, then shift to insects at around 10 cm, gradually eating more fish as they mature. Once they achieve a length of about 30 cm, they feed almost entirely upon fish.
Their usual habitat is the backwaters of the turbulent and turbid rivers that make up the Colorado system.
The species was once found throughout the Colorado basin, so occurred in Arizona, California, Colorado, Nevada, New Mexico,Utah, and Wyoming, as well as in Mexico. Damming and habitat alterations have confined the species to the upper Colorado drainage; currently, remnant populations are known from the Green River, Gunnison River, White River, San Juan River, and Yampa River. Additionally, land managers in the past have attempted to reduce the native fish population of the Colorado basin in favor of sport fishing. In the mid-1960s, the Federal government poured the poison rotonone into the Green and San Juan Rivers, attempting to create an environment supportive of non-native sportfish.[2] They have been transplanted to the Salt River and Verde River, both outside their native range.
Recovery efforts are focused on operating dams to create more of a natural flow pattern, improving fish passage up- and downstream, and restricting stocking of nonnative fish to reduce ecological interactions. Thus far, progress in recovering the pikeminnow has been limited.
Because of the program's cost, the conflicts with nonnative sportfish such as bass, and the fact that the species is not considered either a sportfish or foodfish, recovery efforts are controversial.