Early scale growth characteristics of the New Zealand snapper, chrysophrys auratus (Forster), with reference to selection of a scale‐sampling site
Paul, L. J.; Paul, L. J.; Fisheries Research Division, Marine Department
Журнал:
New Zealand Journal of Marine and Freshwater Research
Дата:
1968
Аннотация:
SummaryScales from 17 body areas of juvenile snapper, Chrysophyrs auratus (Forster), were examined to determine scale growth characteristics, with the aim of denning the most suitable body site for routine scale‐sampling. Least‐square regressions of fish length on scale measurement from 0+ fish were calculated for several body areas, and back‐calculations were made to fish length at first annulus (L<sub>1</sub>) from a sample of 1+ fish, using both the “uncorrected” and “corrected” formulae.The overall fish/scale relationship is curvilinear, but high correlation coefficients show that fish/scale regressions from 0+ snapper may be taken as essentially linear. Such regressions give hypothetical fish lengths at scale formation of 8–23 mm. Mid‐body scales form at 10–14 mm, caudal scales earlier, head scales later.Back‐calculated L<sub>1</sub> values from each area were compared with the mean for the whole body. Using the uncorrected formula there is a general trend for them to be lower than the mean at the head and higher at the tail, while the mid‐body region shows minimum variation from the mean. These variations are caused at least partly by differences in time of scale formation. The corrected formula gives smaller L<sub>1</sub> variations and a mean back‐calculated L<sub>1</sub>almost identical to an observed L<sub>1</sub> from independent length frequency data.The observed variations in scale structure and growth suggest that the “pectoral area”, bounded by the lateral line and the ventral edge of the pectoral fin, is the most suitable site for scale sampling.
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