Short communicationApplication and utility of using otolith weights in the ageing of three flatfish species

- Age estimates are integral to fisheries research, relying on ageing body structures.
- Improved age estimates using otolith weight: fish length relations were determined.
- Models revealed strong relationships and so high utility in improving fish ageing.
- Their utility may be inhibited where their values overlap between age classes.

The relationship between fish length and otolith weight for the three flatfish species Plaice Pleuronectes platessa, Common sole Solea solea and Common dab Limanda limanda sampled from Poole Bay, England, were analysed to identify their utility in deriving estimates of age (in years). Following estimations of age from otolith microscopy, predictive models using discriminant function analysis and logistic regression were developed using the parameters age estimate, fish length and otolith weight. These revealed that the estimated ages from microscopy were relatively consistent with their relationship between total length and otolith weight, with agreement in the classification of age groups across the three species and their five age groups of between 69 and 100%. Agreement <100% tended to occur where there were overlaps in otolith weight and length for specific age classes. Thus, whilst use of otolith weight: fish length relationships have high utility in helping improve the accuracy of age estimates from otolith microscopy, difficulties may remain where there are overlaps in these parameters between age groups.