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<br />StudY Area: <br /> <br />The two drift-netting stations for this study will be the San Juan River between RM 128 and Mexican Hat (RM <br />53). Under this scope of this project, we do not anticipate making any collections in the reach of the San Juan <br />River under the jurisdiction of the National Park Service. <br /> <br />Objectives: <br /> <br />1. Detennine the temporal distribution of San Juan River ichthyoplankton in relation to the hydrograph <br /> <br />2. Provide comparative analysis of the reproductive success of San Juan River fishes <br /> <br />3. Attempt to characterize downstream movement ofichthyoplankton <br /> <br />4, Attempt to validate presumed spawning period of Colorado River pikeminnow <br /> <br />5. Institute a short-tenn but intensive sampling regime in the proximity of the presumed Colorado <br />pikeminnow spawning bed using the MEC as the principal collecting device. <br /> <br />Metbods: <br /> <br />Daily drift samples will be collected at two predetermined localities (Four Comers and Mexican Hat) starting in <br />early July and continuing until the end of August. Collections will be made using MEC each day at dawn and <br />dusk for about two-hours. The amount of water filtered by each net (m') will be measured by mechanical tlow- <br />meters suspended in the center of the nets. This infonnation (m') will allow us to determine catch per unit <br />effort based on volume of water sampled versus time sampling, At the end of each sampling period, the <br />collections will be labeled with unique field numbers and preserved in 5% buffered fonnalin, <br /> <br />All fish specimens will be identified and counted. In addition, specimens will be assigned to more coarse <br />categories such as "drift" and "incidental", The fonner category refers to individuals with minimal or no <br />control over thcir longitudinal movement. The latter classification refers to individuals whose developmental <br />stage should have allowed them to avoid capture in passive drift nets. <br /> <br />Collection data will be converted to catch rate and compared across and within sites by species, In addition, <br />catch rate between and within sites will be compared across time. Specimens will be distinguished and <br />compared by residence status (native versus non-native) and catch rate over-laid with the annual hydrograph. <br /> <br />Products: <br /> <br />Separate draft reports for the 2001 passive larval drift sampling activities and collection efforts downstream of <br />the putative spawning bar will be prepared and distributed by 31 March 2002 to the San Juan River Biology <br />Committee for review. Upon receipt of written comments, that report will be finalization and disseminated to <br />members of the San Juan River Biology Committee by I June 2002. Fish collected from those studies will be <br /> <br />11 <br />