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<br /> Northern pike (Eon uci ) were radiotagged in all study areas in <br /> cooperation with CROW to determine habitat use and movement during winter and <br /> spring and to gather spawning data. During Winter 1, northern pike were <br /> radiotracked only at locations where Colorado squawfish were present. All <br /> northern pike radiotags were on the 30 MHz frequency band as opposed to the 40 <br /> MHz Colorado squawfish band. consequently, tracking the two species required <br /> different radio receivers and loop antennae. If northern pike were detected, <br /> habitat use, depth, velocity, and distance from squawfish were recorded. <br /> During Winter 2, CDOW research personnel tracked northern pike trout the <br /> winter; therefore, our efforts were less intensive during winter but were <br /> intensified during spring when we tracked bath squawfish and northern pike. <br /> Fish were tracked on a biweekly schedule during fall 1987 (Table 1). On <br /> each trip, an attempt was made to contact all fish by floating in a canoe <br /> through each study area. When fish were located, they were monitored to <br /> obtain two 15-minute observations at a stationary location. In addition, two <br /> fish were monitored each week for an additional 4-hr period. These long-term <br /> observations were systematically alternated between the three study groups and <br /> three 8-hr daily time periods. This study design provided an observation in <br /> each of the 8-hr time periods in all three study groups while ensuring that <br /> different groups and time periods were monitored each week. The 8-hr time <br />periods were: 0401-1200, 1201-2000, and 2001-0400. The starting time of each <br /> 4-hr observation period was randomly selected from the first 5 hr in each 8 -hr <br /> daily time period. One fish from each group was selected without replacement <br /> from those found on each biweekly trip. The fall long-term sampling design <br /> included observations on a total of nine fish (three fish from each of three <br /> groups covering each of the three daily time periods in each group). Physical <br />' habitat measurements were recorded at each location at which a fish spent 15 <br />ut <br />i <br /> m <br />n <br />es. <br />During Winter 2, fish were tracked in all three study areas on each <br /> biweekly trip. Fish were monitored as they were located in each study area. <br />Two 15-minute observations were obtained on each fish located. Study areas <br /> were sampled according to a systematic schedule. Long-term observations were <br /> shortened from 24 to 2.5 hr and were made during twilight periods to ensure <br />' that times early and late in the day would be adequately represented in the <br /> data base. On each biweekly trip a fish was monitored during the morning and <br /> evening twilight periods according to a systematic sampling design. <br />t Habitat mammemerrts Winter 1 <br /> At the conclusion of a monitoring period, habitat measurements were taken <br />' at all sites at which fish spent 30 or more minutes. sites were determined by <br /> triangulation from 2 to 5 transects which were previously marked by survey <br /> flags placed along the bank during monitoring. Measurements taken were water <br /> depth, velocity, substrate, cover, and water temperature. When fish habitat <br />' was free of ice, measurements were taken from a boat or by wading. When ice <br /> formed over the site and was considered unsafe to walk upon, access to the <br /> fish location was achieved by sitting in a small inflatable raft at waters <br />edge and pushing it over the surface of the ice using a wading rod. Throughout <br /> most of the winter the ice was thick enough to walk upon safely. However, a <br /> small inflatable raft was often taken out on the ice as a safety precaution <br /> and to carry measure I equipment. Depth was measured using a 10-foot depth <br />' <br />I <br />rod (1\2 inch electrical conduit narked in 0.1 foot increments). Velocity was <br />11 <br />1