Accuracy of age estimates in spring spawning herring (Clupea harengus L.) reared under different prey densities

摘要

This study shows that the otolith microstructure provides useful information for age determination of herring larvae with normal growth. However, the experiments also reveal the importance of being cautious when aging young and/or slow growing larvae. Limited resolution of the light microscope, causing several increments to be invisible, is considered to be the main reason for the low accuracy found in slow growing larvae. Limited resolution of the light microscope may also explain why the accuracy is so dependent on the otolith growth when it is less than 0.8 mum/day. It is concluded that the average increment width of the otolith provides useful information to identify larvae in danger of receiving highly biased age estimates.