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

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mainstem to the GCDAMP and managers. It will also deliver other species metrics, likely to include results of closed population estimates and juvenile abundance from the LCR. This project was reviewed by the 2009 PEP for Grand Canyon Fishes. The panel recommended that because of the inherent variability in the ASMR (for example, estimates of growth and mortality rates limit its ability to detect fine scale changes), preparing annual updates of the model was an inefficient use of personnel time, especially for the long -lived HBC. The PEP also observed that the ASMR has only limited sensitivity to detect small annual population changes, and that it requires tremendous personnel and computer resources to generate. Based on these observations, the PEP recommended that the ASMR be updated every 3 to 5 years. Because the GCMRC is planning to prepare the next State of the Colorado River Ecosystem in Grand Canyon (SCORE) report in FY2011, the GCMRC will accelerate this recommendation for the next iteration and include an update of ASMR in the FY2011 SCORE report. In the future, the GCMRC intends the next iteration of the ASMR following the FY2011 update will be scheduled for FY2014, consistent with the PEP recommendation. Updates will include not only estimates of HBC abundance and recruitment from ASMR, but also summaries of annual catch -rate and size composition estimates from LCR hoop net sampling, summaries of annual catch -rate and size composition estimates from mainstem Colorado River hoop and trammel net sampling, and closed population abundance estimates of HBC adults and rearing juveniles in the LCR as these data are available. Finally, the applicability of similar techniques to those described above will be evaluated to assess stocks of flannelmouth sucker and bluehead sucker. The GCMRC fisheries biologist will work with agency and cooperative personnel to evaluate the utility of the remote passive integrated transponder (PIT) tag antenna project to provide information useful in determining movement rates of HBC into and out of the LCR, empirical capture probability estimates of LCR hoop het sampling, and PIT tag recapture information for inclusion in ASMR. The 2009 PEP for Grand Canyon Fishes made a series of recommendations that direct shifting monitoring efforts to decrease efforts in the LCR and increase efforts in the mainstem of the Colorado River, subject to an analysis of the existing data to see if their recommendations are consistent with the data. The GCMRC fisheries biologist working on this project will be responsible for assembling and /or conducting the analyses necessary to evaluate the recommendations. AZGFD and USFWS personnel to support this effort will also conduct data analyses of individual projects. If the recommendations are found to be warranted, the shift to different monitoring will be initiated in FY2011; these projects are described elsewhere in Goal 2 of this work plan. If the data analyses are not found to support the recommendations, projects will revert to the work plans described for FY2010. The full analysis of all the data will not be required in FY2011, so there will be some shifting of the fisheries biologist time to other projects. Links /Relationships to Other Projects The status and trend of the Grand Canyon HBC population are two of the key metrics utilized in GCDAMP to evaluate the success of the GCDAMP and actions undertaken under the sponsorship of the GCDAMP. Therefore, annually updating the HBC catch rates and size -class composition and updating ASMR model runs every 3 years is related to many other GCDAMP work plan elements, especially experimental actions such as the March 2008 High Flow Experiment (described in a separate science plan) or removal of nonnative fish. The annual HBC population status will be important to projects studying biotic and abiotic aspects of the system— including the aquatic food base, riparian vegetation 23