A new otolith image contour descriptor based on partial reflection

Abstract

In this paper we propose a new contour descriptor for reconstructing fish otolith contours that uses half the number of coefficients needed by the classical elliptical Fourier descriptors (EFDs) for the same accuracy. The efficiency of the proposed shape descriptor has been tested with two different species, Liza aurata and Liza ramada, belonging to the family Mugilidae (http://aforo.cmima.csic.es), and two populations (from the USA and Canada) of the family Merlucciidae. These groups are characterized by high similarity between species; therefore, accurate, detailed shape analyses of their otoliths can help to identify and discriminate morphologically close species or different populations. For comparative purposes the descriptor was also tested with specimens of Mullus barbatus (Family Mullidae). For a certain number of coefficients (<50) the new descriptor clearly outperforms the reconstruction accuracy of the EFD.