The use of hard structures such as sagittal otoliths, vertebrae and
dorsal spines is generally the most reliable method for quantifying
age and growth in fishes. Initial investigations found that scales,
vertebrae and dorsal spines from wahoo were unsuitable for estimating
age and growth (Franks et al., 2000; Hogarth, 1976). Sagittal
otoliths appear to be more reliable for aging wahoo. However, conjecture
exists whether whole or sectioned otoliths provide better
interpretability of growth bands. Early research found that growth
increments were clearly visible and easily interpreted in whole
otoliths from wahoo (Hogarth, 1976). However, as the estimated
longevity of wahoo from this study was half that of more recent
studies (i.e., 5 years), the reliability of this method may be questionable.
Kishore and Chin (2001) also believed that whole otoliths
displayed clearer increments than sectioned otoliths, which displayed
no visible discontinuity in the otolith accreting material.
In contrast, McBride et al. (2008) suggested that the readability of
whole otoliths was not confidently repeatable and, most importantly,
did not allow for measurement of marginal increments in
order to validate the frequency of increment deposition. In an
attempt to increase the visibility of growth bands, Franks et al.
(2001) stained and etched sectioned wahoo otoliths, which proved
unsuccessful.
The use of hard structures such as sagittal otoliths, vertebrae anddorsal spines is generally the most reliable method for quantifyingage and growth in fishes. Initial investigations found that scales,vertebrae and dorsal spines from wahoo were unsuitable for estimatingage and growth (Franks et al., 2000; Hogarth, 1976). Sagittalotoliths appear to be more reliable for aging wahoo. However, conjectureexists whether whole or sectioned otoliths provide betterinterpretability of growth bands. Early research found that growthincrements were clearly visible and easily interpreted in wholeotoliths from wahoo (Hogarth, 1976). However, as the estimatedlongevity of wahoo from this study was half that of more recentstudies (i.e., 5 years), the reliability of this method may be questionable.Kishore and Chin (2001) also believed that whole otolithsdisplayed clearer increments than sectioned otoliths, which displayedno visible discontinuity in the otolith accreting material.In contrast, McBride et al. (2008) suggested that the readability ofwhole otoliths was not confidently repeatable and, most importantly,did not allow for measurement of marginal increments inorder to validate the frequency of increment deposition. In anattempt to increase the visibility of growth bands, Franks et al.(2001) stained and etched sectioned wahoo otoliths, which provedunsuccessful.
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