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<br />. <br /> <br />. <br /> <br />analysis. Quist et al. (2006) evaluated between-reader precision of aging results for various <br /> <br />catostomid species from analysis of fin rays, cleithra, opercular bones, and scales in comparison <br /> <br />with age results from otolith analysis. They found that one reader was nearly accurate at <br /> <br /> <br />identifying otolith age using the cleithra, but when this reader did err, he generally <br /> <br /> <br />underestimated otolith age. The second reader consistently underestimated otolith age by two to <br /> <br /> <br />three years, suggesting that it is quite easy to underestimate the age of catostomid species using <br /> <br /> <br />c1eithra aging techniques. In addition, Sharp and Bernard (1988) also point to difficulty in aging <br /> <br /> <br />lake trout using cleithra techniques. A direct quote taken from their abstract exemplifies their <br /> <br /> <br />concerns with using c1eithra for aging lake trout in Alaska lakes, "Estimated ages from cleithra <br /> <br /> <br />and whole vertebrae were, respectively, too imprecise and too low for these structures to be <br /> <br />useful in age validation studies." <br /> <br />Even though these studies looked at accuracy of age analysis using cleithra from other <br /> <br /> <br />species, their findings suggest that the use of cleithra in aging fish is not extremely accurate. <br /> <br /> <br />Given these fmdings and the significant overlap of lengths at various ages (i.e., in 2001, a 980 <br /> <br /> <br />mm fish was identified as an age-7 fish, but a 559 mm fish was identified as age-9), we felt more <br /> <br /> <br />comfortable grouping pike into YOY, juvenile, and adult. It is possible, according to data from <br /> <br /> <br />CDOW (unpublished) that the 980 mm fish could have come from Stagecoach Reservoir; this is <br /> <br /> <br />within the observed range of normal growth for northern pike in this reservoir. However, the 559 <br /> <br /> <br />mm fish shows extremely slow growth rates for an age-9 fish based on observations of <br /> <br />Catamount and Stagecoach reservoirs and the Yampa River. Since we cannot be certain whether <br /> <br />the observed variation is due to error in the aging results or to variation in growth rates, this age <br /> <br />class grouping likely reduced much of that error (i.e., both of the fish mentioned above are adult <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />27 <br />