Meeting Abstract

32.5  Tuesday, Jan. 5  Feeding behavior and jaw kinematics in Ptychocheilus lucius, an endangered, cyprinid piscivore. BURNETTE, M.F.*; GIBB, A.C.; Northern Arizona University; Northern Arizona University morgan.burnette@nau.edu

Prey capture in piscivorous fishes is thought to be restricted by two factors: the body depth of the prey and the size of the predators mouth gape; previous studies have established the optimal prey depth to predator gape ratio as 0.4-0.7. In this study we investigate feeding behavior of the endangered Colorado pikeminnow, Ptychocheilus lucius, historically the top predator in the Colorado river and its tributaries. Our overarching goal is to track changes in gape and prey capture behavior across development to determine at what age and size juvenile pikeminnow are capable of capturing native and/or introduced fish species. Study animals were obtained from Bubbling Ponds Native Fish Hatchery in Cornville, Arizona as very young juveniles and reared in captivity at Northern Arizona University. High-speed digital-imaging was used to record feeding trials: foods offered to animals during these trials included frozen red mosquito larva, frozen Artemia, and live juvenile poecilids. Preliminary results suggest that the upper limit for the prey depth: gape ratio is approximately 0.7 (that is, live prey that exceeded 0.7 of the predators gape were not consumed). Consequently, fish smaller than 38 millimeters are incapable of taking juvenile poecilids, which are among the smallest juvenile fish present in the Colorado. By tracking behavioral changes in P. lucius as it transitions from a non-piscivorous to a piscivorous life history stage, we hope to provide information that may aid in the management and recovery of this imperiled species.