Critical Rearing Grounds for the Endangered Colorado Pikeminnow (Ptychocheilus lucius): Management Challenges in a Rapidly Changing Ecosystem.

Authors: Christopher Michaud

Year: 2018

Abstract

The placid waters of the canyon-bound and alluvial reaches of both the Colorado and Green Rivers immediately upstream of their confluence form a large proportion of the remnant nursery habitat critical to the survival of the endangered Colorado Pikeminnow. This big river fish, endemic to the Colorado River Basin, uses 120 miles of the lower Green River and 110 miles Colorado River for rearing and recruitment of early life stages. The low-velocity habitats selected by these fish exhibit a low level of stability through time. Discharge has a large impact on quality and abundance of low-velocity habitats. Spring runoff frequently inundates these habitats, whereas extreme low water has the tendency to drain habitats or isolate them from the main channel. Monsoonal activity with consequent flow spikes will inundate habitats with fine sediments reducing their value. Complementing natural stochastic events are a suite of anthropogenic influences. Over the past 130 years, human activity has added multiple factors influencing critical rearing habitat. These include water development, establishment of exotic invasive plant and fish species and global climate change.