Life history of the Colorado squawfish, Ptychocheilus
lucius, and the Colorado chub, Gila robusta, in the Green River in Dinosaur National Monument, 1964-1966.
1 4 36 Erithizon dorsatum Enhydra lutris 1 Phoca vitulina Vulpes vulpes Martes americana Lutra canadensis Ondatra zibethicus 5 Mustela vison 3 Sylvilagus bachmani Aplodontia rufa indeterminate large mammal 12 66 212 indeterminate medium mammal 7 12 indeterminate small mammal 7 Ptychocheilus oregonensis 36 Mylocheilus caurinus 12 Acrocheilus alutaceus Gila bicolor small Cyprinidae 59 indeterminate Cyprinidae 2 Catostomus macrocheilus 72 Cyprinidae/Catostomidae 2 54 23 Thaleichthys pacificus 1 Gasterosteus aculeatus 24 Acipenser sp.
Two species (Catostomus macrocheilus; Ptychocheilus oregonensis) sometimes attain weights of 2-3 kg and lengths of half a metre (Wydoski & Whitney 1979), but are usually much smaller than this.
The Colorado pikeminnow Ptychocheilus lucius is a warm-water, potamodromous, picscivore and is the largest cyprinid in North America.
Observations on the distribution and movements of Colorado squawfish, Ptychocheilus lucius, in the San Juan River, New Mexico, Colorado, and Utah.
Three other endangered species of fish inhabit the Colorado River Basin, the humpback chub Gila cypha, Colorado pikeminnow Ptychocheilus
lucius, and razorback sucker Xyrauchen texanus (United States Fish and Wildlife Service, 2002b, 2002c, 2002d).
Although Gila (Vanicek and Kramer, 1969), Notemigonus (Johnston and Page, 1992), and Ptychocheilus
(Vanicek and Kramer, 1969) are non-territorial, species of Rhinichthys (Raney, 1940, 1958; Mueller, 1984), Pteronotropis (Albanese, 2000; C.
Digestion rates and gastric evacuation times in relation to temperature of the Sacramento squawfish, Ptychocheilus
Bonytails of all sizes would be susceptible to predation by larger-bodied predators including the nonnative northern pike Esox lucius or the native Colorado pikeminnow Ptychocheilus
The Iowa darter might be particularly problematic if populations expand in backwaters of the Green River because they may compete for food resources or prey upon larvae of the endangered Colorado pikeminnow Ptychocheilus
lucius or razorback sucker Xyrauchen texanus.