A discrete model of the 2-D fish scale anisotropic pattern and its application to development of the world ocean ichthyological observation network

A discrete model of the fish scale incremental pattern is proposed, which takes into account the incremental structure in 2-D. This model is based on a representation of the fish scale pattern as a Boolean function, taking anisotropy in the form of discontinuities and convergences of incremental structural elements into account, and the widths of growth increments in different directions. The notion of the index of structural anisotropy of the fish scale pattern is introduced. This index is a measure of the fuzziness encountered in quantitative assessments of 2-D fish scale growth rate. Processing of Atlantic salmon (Salmo salar) fish scales show that the model is quite robust: damage and other sources of anisotropy do not result in catastrophic errors in growth rate quantification. The model of the fish scale pattern allows one to develop a database of hundreds of thousands of fish scales from the World Ocean. Optical sensors for imaging of fish scale patterns and data transmitting devices could be set up on fishing vessels in order to automatically update the database and to obtain information about the real-time status of the fisheries.