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<br />. <br /> <br />. <br /> <br />between years and to catch rates from the Yampa River, the likely source population, to discuss <br /> <br />the effectiveness of the program. <br /> <br />. <br /> <br />Age Analysis <br />Cleithra were used to age northern pike (n=320) collected from 2001 through 2005. <br /> <br />Cleithra were first cleansed in boiling water to remove soft tissue. Following accepted protocols <br /> <br />(Campana 2001), crewmembers counted annuli under a microscope to determine age. To better <br /> <br />make sense of the cleithra data, age results were lumped into three groups: young-of-year (YOY: <br /> <br /> <br />300 mm or less), juvenile (ages 1-3: 301-520 mm), and adult (4+: 521+mm). This length at age <br /> <br /> <br />grouping was consistent with Brown (1971) who aged northern pike in streams in Montana, and <br /> <br /> <br />Scott and Crossman (1973) who found that both male and female northern pike in the northern <br /> <br /> <br />United States will be mature by age four (males will mature at two to three years and females at <br /> <br /> <br />three to four, but all will be mature at age four). <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />Stomach Content Analysis <br /> <br /> <br />Stomach content analysis was conducted from 2002 through 2005. In the field, stomachs <br /> <br /> <br />were individually preserved in 95% alcohol. In the laboratory, contents were identified to <br /> <br /> <br />species, if possible. Lengths were taken on all native fish identified within the stomach. Crews <br /> <br /> <br />did not attempt to identify partially digested materials. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />15 <br />