This paper deals with the automation of the acquisition of age and growth data from the analysis of otolith images. One of the key component of such it system is the automatic detection of the growth center, which serves as the basis for further processing (2D ring segmentation, age and growth estimation,...). To this end, we develop a new and well-founded approach combining a morphological analysis of image level sets to the a contrario, detection principle. This approach leads to a robust parameterless scheme, whose efficiency is demonstrated by an evaluation carried out for a set of several hundred of plaice otoliths. (c) 2005 Elsevier B.V. All rights reserved.