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<br />548 <br /> <br />Early Life Stage: Nursery Habitat Requirements <br />1997 Work Plan <br />Utah Division of Wildlife Resources <br /> <br />Background: <br /> <br />This component of research has been designed to characterize the early life stage habitat <br />requirements of the ichthyofaunal community in the San Juan River system. It is directed at <br />specifically determining the seasonal use oflow-velocity habitats (nursery) by young-of-the-year <br />(YOY) and age-1 native and nonnative species. Platania (1990) estimated that Colorado <br />squawfish spawned in the San Juan River during the months of July and August. Intensive <br />sampling oflow-velocity habitats is initiated in mid-August. Fall (September) sampling <br />characterizes the fish community in low-velocity habitats and represents the faunal conditions as <br />the community prepares to over-winter. Those fish that over-winter are sampled during the <br />March period. Althoughthese protocol have been written to answer specific questions on the San <br />Juan River, much of the standardized sampling procedures draw heavily from existing protocols <br />used currently on other Upper Basin rivers. The design is not intended to mimic those efforts, but <br />rather to provide a method for comparison of data collected in the different systems. <br /> <br />Objectives for FY97: <br /> <br />1) To empirically monitor the annual recruitment ofYOY Colorado squawfish in relation to <br />flow patterns in the San Juan River. <br />2) To determine the quality and quantity oflow-velocity habitats in the San Juan River for <br />use by Colorado squawfish by experimentally stocking YOY fish. <br />3) To determine the effects of diversion canals on YOY Colorado squawfish drift/movement <br />(e.g., stranding, etc.). <br />4) To characterize the early-life stage icthyofaunal community in low-velocity (nursery) <br />habitats. <br />5) To characterize nursery habitats and their use in the San Juan River system. <br />6) To determine overwinter survival of experimentally stocked age-1 sized (approximately <br />50-55 mm) Colorado squawfish. <br />7) To determine what habitats juvenile Colorado squawfish utilize. <br /> <br />Methods: <br /> <br />Fish Communitv/Y oung-of-thee Year Monitoring <br /> <br />One Fall (September) sampling trip will be conducted to characterize the fish community in low-- <br />velocity habitats river wide (Table 1). This trip will start at the Hogback diversion in New <br />Mexico (RM 158.6) and terminate at RM O. Two backwaters in each 5 mi reach will be sampled. <br />Protocols will be consistent with 1992, 1993, 1994, 1995, and 1996 methods. <br /> <br />The contents of all seine hauls will be searched for target species. Target species will be <br />measured to the nearest millimeter total length (TL) and released. All other specimens will either <br /> <br />8 <br />