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• provide baseline status and trend information to be used as a backdrop to understand the <br />mechanisms controlling native fish population dynamics, and <br />• evaluate the efficacy of particular management policies in attaining program goals. Finally, <br />results from this project are potentially useful in assessing changes to Federal Endangered <br />Species Act listing status of HBC in the Colorado River. <br />Strategic Science Questions <br />Primary SSQ addressed: <br />SSQ 1 -1 To what extent are adult populations of native fish controlled by production of young fish <br />from tributaries, spawning and incubation in the mainstem, survival of YoY and juvenile stages in <br />the mainstem, or by changes in growth and maturation in the adult population as influenced by <br />mainstem conditions? <br />Additional SSQ addressed: <br />SSQ 1 -8 How can native and nonnative fishes best be monitored while minimizing impacts from <br />capture and handling or sampling? <br />The Adaptive Management Program Science Advisors have articulated the following science question, <br />which is partially addressed by this project: <br />SA 1 What are the most limiting factors to successful humpback chub adult recruitment in the <br />mainstem: spawning success, predation on YoY and juveniles, habitat (water, temperature), <br />pathogens, adult maturation, food availability, competition? <br />Information Needs <br />RIN 2.2.8 What combination of dam release patterns and nonnative fish control facilitates <br />successful spawning and recruitment of humpback chub in the Colorado River ecosystem? <br />RIN 2.4.2 Determine if suppression of nonnative predators and competitors increases native fish <br />populations. <br />Methods and Tasks <br />To provide HBC status and trend information, the Grand Canyon Monitoring and Research Center <br />(GCMRC) mark - recapture database will be annually updated with the most recent data collected during <br />routine monitoring efforts including mainstem electrofishing and netting and the Little Colorado River <br />monitoring efforts (see GCMRC /AMP 2011 -12 work plan for additional details). Following this update, <br />the HBC mark - recapture database will be reanalyzed using (where appropriate) both open and closed <br />mark - recapture -based abundance estimators to provide the most current information on HBC status and <br />trends. In particular, the ASMR models ( Coggins and others, 2006a and 2006b; Coggins, 2007; Coggins <br />and Walters, 2009) will be used to determine trends in HBC abundance and recruitment over multiyear <br />time scales. Over annual time scales, this project will assemble and deliver summaries of annual catch <br />rate and size -class composition of HBC and other species from the Little Colorado River (LCR) and <br />22 <br />