Flood stages for life stages: assessing the effectiveness of habitat restoration and water management to promote Rio Grande silvery minnow recovery

Authors: Deanna Strohm, Riich Valdez, Ken Richard

Year: 2016 (xlviii)

Abstract

Habitat restoration and water management are two of four primary conservation principles the U.S. Fish and Wildlife Service requires to promote recovery of endangered Rio Grande silvery minnow (Hybognathus amarus; silvery minnow). As part of a collaborative adaptive management plan, the New Mexico Interstate Stream Commission (NMISC) coordinated an experimental water release (>2,000 cfs, May 16 ’ June 19, 2016) in the Middle Rio Grande River to assess the timing, magnitude, and duration of flows necessary to inundate restored floodplain habitat and promote silvery minnow recruitment. During spring 201 6, SWCA Environmental Consultants, on behalf of the NMISC, sampled six select restoration sites in the Albuquerque and Isleta Reaches of the Middle Rio Grande to monitor and quantify habitat restoration and flow management success for all silvery minnow life stages. Across restoration sites, silvery minnow were the second most abundant adult species and most abundant larval species we collected (18 % adult and 93% larval in Albuquerque Reach; 8% adult and 73 % larval in Isleta reach), and we documented the presence of silvery minnow eggs at four of six restoration sites. During these increased flows, we collected silvery minnow a dults beginning on our first sampling date (May 21, 2016) through our last sampling date (June 17, 2016) silvery minnow larvae from June 1, 2016 through our last sampling date, and silvery minnow eggs from our first sampling date through May 30, 2016. Thus, we demonstrate that restored floodplains provide habitat for all silvery minnow life stages, and specifically, important nursery habitat for early life stages when fishes naturally experience the highest rates of mortality. From this study, we can guide future monitoring efforts to better quantify important habitat features and design adaptive water management strategies to maximize restoration success and annual silvery minnow recruitment in the Middle Rio Grande system.