Colorado pikeminnow
Encyclopedia
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
.
, 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 elder
s, 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.
ns, copepod
s, and chironomid larvae, then shift to insect
s 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.
, 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. They have been transplanted to the Salt River
and Verde River
, both outside their native range.
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.
Cyprinid
The family Cyprinidae, from the Ancient Greek kyprînos , consists of the carps, the true minnows, and their relatives . Commonly called the carp family or the minnow family, its members are also known as cyprinids...
fish of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
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
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...
basin of the southwestern United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, it was formerly an important food fish for both Native Americans
Native Americans in the United States
Native Americans in the United States are the indigenous peoples in North America within the boundaries of the present-day continental United States, parts of Alaska, and the island state of Hawaii. They are composed of numerous, distinct tribes, states, and ethnic groups, many of which survive as...
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
Bonytail chub
The bonytail chub or bonytail, Gila elegans, is a cyprinid freshwater fish native to the Colorado River of Arizona, California, Colorado, Nevada and Utah in the southwestern United States...
, Humpback chub
Humpback chub
The humpback chub Gila cypha, is a federally protected fish that lived originally in fast waters of the Colorado River system in the United States. This species takes its name from the prominent hump between the head and dorsal fin, which is thought to direct the flow of water over the body and...
, and Razorback sucker
Razorback sucker
The razorback sucker, Xyrauchen texanus, is an endangered fresh water sucker of rivers in the Colorado River drainage of western North America.-Description:...
.
Description
Like the other three species of pikeminnowPtychocheilus
Squawfish or pikeminnows are cyprinid fish of the genus Ptychocheilus consisting of four species native to western North America. Voracious predators, they are considered an "undesirable" species in many waters. This is largely due to the species' perceived tendency to prey upon small trout and...
, it has an elongated body reminiscent of the pike
Esox
Esox is a genus of freshwater fish, the only living genus in the family Esocidae — the esocids which were endemic to North America, Europe and Eurasia during the Paleogene through present.The type species is E. lucius, the northern 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
Pharyngeal teeth
Pharyngeal teeth are teeth in the pharyngeal arch of the throat of cyprinids, suckers, and a number of other fish species lacking teeth.Popular aquarium fish such as goldfish and loaches have these structures. Members of the Botia genus such as clown loaches are known to make distinctive clicking...
are long and hooked.
The reports of 6 ft individuals are estimates from skeletal remains but a number of community elder
Old age
Old age consists of ages nearing or surpassing the average life span of human beings, and thus the end of the human life cycle...
s, 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.
Biology
Young pikeminnows, up to 5 cm long, eat cladoceraCladocera
Cladocera is an order of small crustaceans commonly called water fleas. Around 620 species have been recognised so far, with many more undescribed. They are ubiquitous in inland aquatic habitats, but rare in the oceans. Most are long, with a down-turned head, and a carapace covering the apparently...
ns, copepod
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...
s, and chironomid larvae, then shift to insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s 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.
Range
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 RiverGreen River (Utah)
The Green River, located in the western United States, is the chief tributary of the Colorado River. The watershed of the river, known as the Green River Basin, covers parts of Wyoming, Utah, and Colorado. The Green River is long, beginning in the Wind River Mountains of Wyoming and flowing...
, Gunnison River
Gunnison River
The Gunnison River is a tributary of the Colorado River, long, in the Southwest state of Colorado. It is the fifth largest tributary of the Colorado River, with a mean flow of 4320 ft³/s .-Description:...
, White River
White River (Utah)
The White River is a tributary of the Green River, approximately long, in the U.S. states of Colorado and Utah. Flows vary from 450 ft³/s late summers in dry years to well over 12,000 ft³/s in spring....
, San Juan River, and Yampa River
Yampa River
The Yampa River is a tributary of the Green River, approximately 250 mi long, in the U.S. state of Colorado. It's located in the Southwestern United States...
. 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. They have been transplanted to the Salt River
Salt River (Arizona)
The Salt River is a stream in the U.S. state of Arizona. It is the largest tributary of the Gila River. The river is about long. Its drainage basin is about large. The longest of the Salt River's many tributaries is the Verde River...
and Verde River
Verde River
The Verde River is the north and northwestern watershed of the Salt River–Verde River Watershed that co-join and enter the Gila River at Phoenix, Arizona, located in the U.S. state of Arizona...
, both outside their native range.
Recovery efforts
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.