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Photo by Unknown Photographer
Photo Courtesy of Utah Division of Wildlife Resources; Utah Division of Wildlife Resources
Colorado Pikeminnow
Ptychocheilus lucius
NatureServe conservation status
Global (G-rank): G1
State (S-rank): S3
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Species range
This species occurs in the large rivers of the Colorado River system. In the Green River drainage, the mainstem is occupied from the confluence with the Colorado River upstream through Dinosaur National Park. This population also occupies the White River to the Colorado state line, the lower 143 km of the Price River, and the lower 10 km of the Duchesne River. The Colorado River population is found in the mainstem from the Lake Powell inflow to the Colorado state line and also the lower 2 km of the Dolores River. The San Juan River population occupies the main stem above the Lake Powell inflow to the Colorado state line
Habitat
This species inhabits large rivers of the Colorado River system that are characteristicly warm and turbid. Adults often occupy deep-water, low velocity eddies and pools and flooded habitats created during high flows during the spring. In the Green River, spawning occurs in canyon-bound reaches over cobble substrate (Stanger 1983, USFWS 2002); free passage of adults to spawning beds is essential. Larvae drift downstream and develop in warm and relatively deep in-channel backwater pools; juvenile fish may spend up to 4 years in or near these habitats.
Food habits
Colorado Pikeminnow have a typical apex predator diet and lifehistory. As juveniles they eat invertebrates that increase in size as they grow starting with small zooplankton working up to aquatic insects. As they transition to adulthood the begin what is called an "ontogenetic diet switch" where their diet changes to almost entirely other fish.
Reproductive characteristics
Colorado Pikeminnow utilize the same reproducive strategy as other native fish that live in the large rivers of the Colorado River Basin. They will migrate to spawning gravels in the spring where the eggs are deposited and fertilized in gravels. Once they hatch the larval fish will drift downstream carried by the current until they settle out in the warmer slower water of backwater channels or wetlands. The young then use these highly productive areas to facilitate their quick growth before they venture back into the main channel of the river as juveniles and adults.
Threats or limiting factors
The numerous threats to this species are derived primarily from the fundamental ecological changes that have followed the damming of major rivers and tributaries in the Colorado River drainage. Although the threats from additional dam construction is relatively low, populations continue to be impacted by altered habitats. Changes in sediment deposition patterns, flow, and temperature caused by dams have resulted in loss and alteration of aquatic habitats and have favored non-native competitors and predators. Small population sizes resulting from population decline and fragmentation may have implications for the long-term genetic diversity of populations; this is of particular concern for the San Juan River population. Construction of dams may also have interrupted spawning migrations.
