Colorado pikeminnow (Ptychocheilus lucius)

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Colorado pikeminnow
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Colorado pikeminnow fact file

Colorado pikeminnow description

KingdomAnimalia
PhylumChordata
ClassActinopterygii
OrderCypriniformes
FamilyCyprinidae
GenusPtychocheilus (1)

The dominant predator in its river habitat, the Colorado pikeminnow (Ptychocheilus lucius), was once so abundant that fishermen could catch it out of rivers just using pitchforks (4). It is the largest species of cyprinid fish (species in the Cyprinidae family) endemic to the Colorado River Basin (5), and once reached lengths of up to two metres (2). These days, Colorado pikeminnows longer than 80 centimetres are an unusual sight (3).

The Colorado pikeminnow is a slender, cylindrical fish (5) with an elongated body and a long, pointed snout (6). The adult has a greenish back with a pale, creamy-yellow belly and silver sides. Juvenile Colorado pikeminnows tend to have a more silver colouration (5).

During the breeding season the head and body of a spawning adult are tinged a pale rosy-red and tubercles appear on the head and paired fins (5).

Also known as
Colorado pikeminnow, Colorado river squawfish, Colorado squafish, Colorado squawfish.
French
Poisson Squaw du Colorado.
Spanish
Pez Squaw del Colorado.
Size
Length: up to 2 m (2)
Weight
up to 20 kg (3)
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Colorado pikeminnow biology

A predatory species, the Colorado pikeminnow feeds on crustaceans, such as copepods and water fleas as a juvenile, then moves onto aquatic insect larvae and small fish, including other minnow species, once fully mature (2). It lacks teeth in its jaws but has a pair of enlarged bones in the throat which possess structures known as ‘pharyngeal teeth’, used to process food. Adults use these sharp, cutting pharyngeal teeth to slice through their prey (6).

Warm water is required for spawning, egg incubation and juvenile survival, so the Colorado pikeminnow mates and lays its eggs in the gravel bed during July and August when temperatures exceed 18 degrees Celsius (7). The Colorado pikeminnow has a mating ritual in which a female, followed by males, swims to the bottom, normally over a crevice, and vibrates to release her eggs, a process known as ‘broadcast spawning’. The males will then swarm around her emitting sperm, trying to fertilise as many eggs as possible (7).

Following fertilisation, it takes about one week for the larvae to emerge from the eggs (3). The larvae then drift downstream to sheltered backwaters (7) where they remain for the next two to four years. The Colorado pikeminnow takes many years to reach full size and can live for up to 12 years (6).

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Colorado pikeminnow range

Restricted to large rivers of the Colorado River basin, USA, the Colorado pikeminnow was once found commonly in the Colorado River and its associated tributaries, but there has been a large reduction from its original distribution (2).

Presently, the majority of the population is found in the Green River. Smaller populations occur in the Upper Colorado and San Juan Rivers (3). It was lost from the lower part of the Colorado River but it has been recently reintroduced using hatchery born fish (2) (6).

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Colorado pikeminnow habitat

The Colorado pikeminnow is a freshwater migratory species. Large adult Colorado pikeminnows like deep, fast-flowing rivers and can be found residing in large, turbid pools found in the main river and its tributaries (3). Smaller Colorado pikeminnows tend to stay in shallow pools or close to the river’s edge where the current is slower (2).

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Colorado pikeminnow status

The Colorado pikeminnow is classified as Vulnerable (VU) on the IUCN Red List (1).

IUCN Red List species status – Vulnerable

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Colorado pikeminnow threats

The Colorado pikeminnow currently occupies just 20 to 25 percent of its historical range (7). The dramatic decline is due to a combination of factors, including reduced water quality, habitat degradation, and the introduction of non-native species, (7).

The increase in the number of dams along the Colorado River poses the biggest threat to the Colorado pikeminnow. Dam installation changes the natural structure of the river habitat and blocks the spawning passages of the Colorado pikeminnow (3). In addition, the still river habitats below the dam encourage the introduction of non-native game species, such as trout, which hunt the larvae and juveniles of the Colorado pikeminnow, and out-compete the adults for food (2).

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Colorado pikeminnow conservation

Conservation efforts for the Colorado pikeminnow have been in place since 1988 when the Upper Colorado River Endangered Fish Recovery Program (UCRRP) was introduced (5). Due to the endemic nature of the population, conservation efforts for this fish are easily focused on the Colorado River (5).

Conservation plans aim to restore the connectivity of the river by creating diversion streams around the dams. This will allow the Colorado pikeminnow to freely migrate  up and down the river so that it can reproduce successfully (5). The plan also includes the removal of non-native species introduced for game fishing, and the reintroduction of the Colorado pikeminnow from captive-bred populations into areas where it has been lost (2). The overall goal is to increase population numbers and restore the Colorado pikeminnow back to its former natural range (5).

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Find out more

Find out more about the Colorado pikeminnow and its conservation:

More information on fish conservation in North America:

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Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

This species information was authored as part of the ARKive and Universities Scheme.
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Glossary

Copepod
A large and diverse group of minute marine and freshwater crustaceans. They usually have an elongated body and a forked tail.
Crustaceans
Diverse group of animals with jointed limbs and a hard external skeleton, characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.
Endemic
A species or taxonomic group that is only found in one particular country or geographic area.
Fertilisation
The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
Incubation
The act of incubating eggs, that is, keeping them warm so that development is possible.
Larvae
Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
Spawning
The production or depositing of large quantities of eggs in water.
Tubercle
A small, rounded, wart-like bump on the skin or on a bone.
Turbid
Cloudy or muddy; not clear.
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References

  1. IUCN Red List (November, 2010)
    http://www.iucnredlist.org/
  2. Moyle, P.B. (2002) Inland Fishes of California. University of California Press Ltd, Berkley.
  3. Gupta, A. (2007) Large Rivers: Geomorphology and Management. John Wiley & Sons Ltd, East Sussex.
  4. Postel, S. and Richter, B.D. (2003) Rivers for Life: Managing Water for People and Nature. Island Press, Washington.
  5. US Fish and Wildlife Services (2002) Colorado pikeminnow (Ptychocheilus lucius) Recovery Goals: Amendment and Supplement to the Colorado Squawfish Recovery Plan.  U.S. Fish and Wildlife Service, Mountain-Prairie Region, Denver, Colorado.
  6. McGinnis, S.M. (2006) Field Guide to Freshwater Fishes of California. University of California Press Ltd, Berkley.
  7. US Forest Service - Colorado pikeminnow (November 2010)
    http://www.fs.fed.us/rm/boise/AWAE/projects/fish_cattle/Colorado%20pikeminnow.pdf
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Image credit

Colorado pikeminnow  
Colorado pikeminnow

© John N. Rinne

Robert Rice on behalf of John Rinne
arkive@wildscreen.org.uk

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