Colorado Pikeminnow: Forgotten Predator of the Lower Colorado River

Authors: David Lance Ward

Year: 2016 (xlviii)

Abstract

Colorado Pikeminnow Ptychocheilus lucius were historically one of the most abundant fish in the Lower Colorado River in the pre-dam era. By the 1970’s they had been extirpated from below Glen Canyon Dam. In 2002, when recovery goals for Colorado Pikeminnow were written it was determined that no conservation actions conducted downstream of Glen Canyon Da m would count toward recovery. This decision was to be re-evaluated during 5-year status reviews, but has not occurred. Adult Colorado Pikeminnow still persist in the Verde River and hundreds of miles of the mainstem Colorado River below Glen Canyon Dam st ill match Colorado Pikeminnow life history requirements. Arguments against repatriation of Colorado Pikeminnow into the lower basin are typically based on fears over potential adverse impacts to other endangered native fishes. These fears appear to be largely unfounded based on gape to body-depth relationships and behavioral adaptations of co-evolved native species. Juvenile humpback chub Gila cypha and razorback sucker Xyrauchen texanus quickly outgrow the gape of all but the largest pikeminnow. Additional data and improved understanding of Colorado Pikeminnow biology indicates revision of the recovery goals may be warranted, to include management actions and recovery criteria for Colorado Pikeminnow in the lower Colorado River Basin.