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<br />reach in critical habitat. As distance increased downstream the number of small adults <br />declined. Large northern pike were distributed throughout the river. <br /> <br />Although removal was considered effective at reducing the number of northern <br />pike, removal effects varied by reach. After initial declines from 2000 to 2001 in all <br />reaches, northern pike numbers continued to decline at Lily Park and increased at <br />Juniper and Maybell in 2002. Removal was most effective at Lily Park apparently <br />because fish were removed at a greater rate than the rate of immigration and <br />recruitment. Reduced immigration at Lily Park was attributed to upstream removals that <br />relieved competitive pressures that would increase downstream dispersal. Reduced <br />recruitment at Lily Park was attributed to the absence of a local source of small fish and <br />the distant source of potential recruits far upstream. Catch rate increases in Juniper <br />and Maybell in 2002 were proportional to an increase in the number of small adults in <br />each reach, with the largest number of small adults in Juniper. For removal to be <br />effective, fish must be removed at a rate greater than the rate of replacement from <br />immigration or recruitment. Effective removal will require increased effort (i.e. more <br />sampling occasions) and removal in areas upstream of critical habitat to reduce <br />immigration into downstream critical habitat reaches. <br /> <br />Northern pike occurred in concentration areas immediately downstream of <br />Juniper and Cross Mountain canyons and in spring backwaters throughout the river. <br />Concentration areas were sinks for northern pike and were recolonized by northern pike <br />between sampling trips. Removal effectiveness could increase by increasing effort in <br />vi <br />