A good exchange participation with 21 readers from 13 laboratories contributed interpreting images of paired calcified structures, otoliths and spines, coming from the same specimen. The mean coefficient of variation and average per cent error were around 20 and 15 respectively. Precision was lower for inexperienced readers than for experienced ones, being experience a major factor in the age interpretation from otoliths viewed under reflected light and for large specimens using spines under transmitted light. There was generally good agreement in the ageing among different structures coming from the same specimen. Otoliths aged using different types of light showed a good agreement with no significant bias (p> 0.05), while spine showed no sign of bias with respect to otoliths viewed under transmitted light (p> 0.05) but a slight under ageing when compared with reflected light otoliths (p< 0.05), with these differences been found in specimens older than 14 years, for which the number of samples was very small. Further standardization of age reading criteria between laboratories and a description of the annual formation of otolith edge type is needed.