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<br />549 <br /> <br />be: 1) identified and enumerated as adults or sub-adults, or 2) preserved in a 10% buffered <br />formalin solution in Whirlpak containers. A sample label will accompany the specimens, and the <br />sample number, date, and San Juan River Mile will be inscribed with permanent marker on the <br />outer bag. <br /> <br />General habitat information will include: 1) date, 2) location, 3) primary habitat type, 4) specific <br />habitat type, 5) river orientation, 6) main channel temperature, 7) habitat temperature, 8) total <br />length, 9) width (at three locations), 10) depth (at nine locations), 11) landmarks, 12) and a <br />sketch of the site. Fish collection information will include: 1) sample number, 2) seine used, 3) <br />time, 4) orientation of haul, 5) length, 6) width, 7) maximum depth, 8) substrate type, 9) fish <br />preserved, and 10) number ofwhirlpaks. <br /> <br />Nursery Habitat: <br /> <br />Five reaches will be sampled in the San Juan River to evaluate Colorado squawfish nursery <br />habitat: Below Hogback (RM 157-152), Mixer (RM 131-126), Montezuma Creek (RM 89~84), <br />Johns Canyon (RM 25-20), and Grand Gulch (RM 13-8). The Clay Hills reach (RM3-RMO) that <br />was being sampled under the UDWR project Ichthyological Community Monitoring of the Lower <br />San Juan River and Lake Powell Inflow Area will be added in 1997, as well. These areas will be <br />sampled in late-March! early-April, late August, and September (Table 1). All backwaters and <br />similar habitat types (i.e. trickle-fed side channels, embayments, pools, etc.) will be sampled. The <br />physical and biological habitat characteristics oflow-velocity habitats will be measured. <br />Relationships between the early life stage ichthyofaunal community and maintenance of nursery <br />habitats will be investigated. The fluvial-geomorphic basis of habitat feature maintenance will be <br />compared to similar habitat types in the Upper Basin. Habitat and fish community information <br />collection will be consistent with that outlined above in YOY monitoring. <br /> <br />Experimental stocking ofYOY Colorado squawfish <br /> <br />To enhance the ability to evaluate nursery habitat we will experimentally introduce YOY <br />Colorado squawfish in 1997 [see the San Juan River Experimental Stocking Plan for YOY <br />Colorado Squawfish (Lentsch et aI. 1996)]. In 1997, 100,000 YOY Colorado squawfish obtained <br />from Dexter National Fish Hatchery will be marked with a unique tetracycline hydrochloride (TC) <br />stain and/or chemical spray mark and stocked into the San Juan River. All of these fish will be <br />approximately 20--40 mm in length, stocked in August, and 20,000 will be stocked approximately <br />1 Ian upstream from each of the five reaches (described above, not including the Clay Hills reach). <br />For the upper most reach, Colorado squawfish will be stocked just below the Hogback Diversion. <br /> <br />The primary objective of experimental stocking is to determine if the quality and quantity oflow- <br />velocity habitats in the San Juan River are sufficient to support retention and recruitment ofYOY <br />Colorado squawfish. All low-velocity habitats (i.e., backwaters, eddies, and shorelines) <br />throughout the five geomorphic reaches will be sampled one week following the release ofYOY <br />Colorado squawfish. This initial sampling willI) determine iflow--velocity habitats within each <br />reach are retaining fish and 2) be in conjunction with current Colorado squawfish nursery habitat <br />sampling (described above) (Table I). After the first sampling, each reach will be sampled <br /> <br />9 <br />