Determining Relative Abundance and Distribution of the Endangered Humpback Chub Downstream of Pearce Ferry Rapid; Lake Mead NRA

The objective of this Agreement is to collaboratively investigate the current distribution and abundance of the Endangered Humpback Chub in the newly formed 15-mile Colorado River reach below Pearce Ferry Rapid to the Lake Mead inflow within Lake Mead National Recreation Area (LAKE). Long-term standardized Humpback Chub monitoring of the Colorado River from Glen Canyon Dam to Lake Mead has been conducted by different entities for almost two decades. However, as the elevation of Lake Mead has decreased since 2000, approximately 15 miles of new riverine habitat below Pearce Ferry formed within LAKE, which may serve as important habitat for native fishes such as Humpback Chub. This agreement will facilitate a partnership between LAKE and G&F, AD allowing investigators from both agencies to combine resources and determine if the Humpback Chub inhabiting the downstream part of the Grand Canyon to the inflow of Lake Mead constitutes a new aggregation of Humpback Chub separate from those upstream. Humpback Chub and other endemic Colorado River species are identified as fundamental natural resources in the LAKE Foundation Document. The National Park Service Management Policies state that the Service will work to protect rare, threatened, or endangered native species. Results of this work directly address Recovery Goals and management components for multiple basin-wide efforts for the Humpback Chub, and could result in consideration of LAKE for inclusion in the lower basin recovery unit. Results of this project will also aid in future distribution predictions relative to changes in water level at Lake Mead. Park managers will be able to use this information to help prioritize projects to protect critical habitat used by Humpback Chub and other native fish, as well as help minimize future negative impacts to the species. Furthermore, results will inform us of the fish community utilizing this reach of the Colorado River, including both native and non-native species of potential management concern.