. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. BLUECILL DELAYED ANNULUS FORMATION 35. 12 13 14 15 16 17 18 19 FORK LENGTH (CM) FIGURE 5. Relationship of ratio of distance from outer annulus to anterior margin to distance from focus to margin (Y/X) to fish length of bluegill with three annuli collected at Lake Nacimiento in 1967. Dashed line separates two age groups. proved extremely difficult to age (Figure 6). The path clear of data points extending roughly from coordinates (
. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. BLUECILL DELAYED ANNULUS FORMATION 35. 12 13 14 15 16 17 18 19 FORK LENGTH (CM) FIGURE 5. Relationship of ratio of distance from outer annulus to anterior margin to distance from focus to margin (Y/X) to fish length of bluegill with three annuli collected at Lake Nacimiento in 1967. Dashed line separates two age groups. proved extremely difficult to age (Figure 6). The path clear of data points extending roughly from coordinates (, ) to (, ) is believed to separate Age II and Age III specimens. In the absence of a more definitive technique, an extension of this line tou/ard the abscissa was used to further delineate the two age cohorts. We regard this procedure as arbitrary, however, and cannot rigorously defend our judgments concerning the age of bluegill depicted by data points near the extended line. Despite these misgivings, we note that such uncertainties involve only a minor fraction of the 1965 bluegill scale collection with two annuli (Figure 6). Specimens judged Age II had a mean ratio (Y/X) of and a mean length of cm ( inches), while those judged Age III had comparable values of and cm ( inches). Bluegill scales with three annuli collected in 1968 produced an array of data points with certain basic similarities to that constructed from the 1965 collection with two annuli (Appendix 3, Figure 6). A path free of data points extended through a portion of the array which required an arbitrary extension in order to age the entire sample. Despite this difficulty, serious uncertainties involved only a very small percentage of the 1968 collection. Other segments of the Lake Nacimiento scale collection, comprised primarily of older individuals, were difficult to age because of small sample sizes. Nonetheless, the technique herein described was applied to these grou
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