Study Plan - Biological Resource Responses to Fall Steady Experimental Flows Feruary 2010

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algae production and organic drift than do the proposed flows, are minimal in this reach. We are not proposing food base data collection in association with the nearshore ecology project because fieldwork for food base was reduced starting in 2009 to complete sample processing, data analysis, and reporting. Monitoring of rainbow trout populations (Project 4) will provide insights into the impacts of flow on fish and addresses, in part, SSQs 3.6, 4.2, 5.4, and 5.6. Work by Korman (Gloss and Coggins, 2005; Korman and Campana, 2009) has provided the most conclusive evidence to date of the relationship between dam operations and fish vital rates (that is, growth and survival). Frequent and low -cost measurements, and the lack of tributary activity and other complicating factors, make it easier to identify the nature of flow /trout interactions in Lees Ferry relative to sites downstream. This work will be continued because understanding the rainbow trout response to experimental flows will help inform scientists about native fish response at downstream locations, where tributary activity will make it harder to separate the effects of flow. We propose additional water temperature data collection (Project 5) because one of the primary mechanisms whereby stable flows might benefit native fish is by increasing nearshore warming. This project is not in GCMRC's fiscal years 2010 to 2011 work plan and would require supplemental funding. These data will be critical for evaluating the degree of nearshore warming that occurs with stable flows across summer and fall and for informing analysis of native fish growth rates among habitat types. Finally, we propose that ecosystem - modeling efforts (Project 6) underway in 2011 and .2012 will include data analysis methods and integration of physical and biological research data into models for response of aquatic ecosystem indicator variables to possible management actions. The goal of this modeling effort is to provide screening of alternative adaptive management proposals for improving responses of performance indicators such as abundance of humpback chub. These models are likely to be developed in an Ecopath with Ecosim (EwE) platform in cooperation with Carl Walters (University of British Columbia) and Josh Korman (Ecometric Research, Inc.). We believe that. this project provides a good framework for separating the effects of flow from other variables such as nonnative fish abundance, changes in food resources, or tributary hydrology. The ecosystem modeling effort will focus and integrate key SSQs and Science Advisor (SA) questions, including indentifying linkages between food web changes and fish population changes in response to flow actions below Glen Canyon Dam: SSQ 3 -5 How is invertebrate flux affected by water quality (for example, temperature, nutrient concentrations, turbidity) and dam operations? SA 1 What are the most limiting factors to successful HBC adult recruitment in the mainstem: spawning success, predation on YoY and juveniles, habitat (water, temperature), pathogens, adult maturation, food availability, competition? In addition, modeling efforts will address responses of native fish to mechanical removal of nonnative fish, fall steady flows, and backwaters created by experimental high flows: 14