Tidsskrift : Fisheries Research , vol. 60 , p. 53–64 , 2003
Utgiver : Elsevier
Trykt : 0165-7836
Elektronisk : 1872-6763
Publikasjonstype : Vitenskapelig artikkel
Sak : 1
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Otoliths of long rough dab (Hippoglossoides platessoides) were analysed using both stereomicroscope and digitised pictures. Approximately 400 fish were aged twice by each technique. The use of digitised pictures gave consistently higher precision of age-determinations. This was shown both graphically and by use of the coefficient of variation. Age determined from digitised pictures was generally higher than that determined by using a stereomicroscope. This was particularly true for older specimens.
For some individuals a change in the zoning pattern in the otoliths was observed. The occurrence of these changes was not closely correlated with the visually determined maturation index.
For fish of similar size otolith radius was correlated with age. The growth rate also influenced otolith morphology. This additional information is incorporated in the outline of an objective age-determination suggested by this study.