Photoidentification allows the study of different species of marine mammals by identifying each animal individually. Generally this is done by studying the marks, scars, shapes of spots... present on the dorsal of dolphins or the tail of humpback whales.

This method allows to obtain several interesting information:

• study the social relations within groups of individuals;
• study the migration of species by recognizing the same animal in several places;
• determine and follow the demographic parameters of populations (abundance, reproduction, growth, mortality...) via what is called the "capture-mark-recapture" method.

In order to carry out these studies, it is often necessary to study catalogs of several hundreds or even thousands of photos. Generally this is done only thanks to the expertise and memory of scientists. However, computerized image analysis tools are becoming more and more necessary as these catalogs grow as they are shared between international organizations.

For example, the North Atlantic Humpback Whale Catalogue is the result of the participation of many managers and associations.

Recently, there is also the Flukebook website which does not only serves as a photo identification catalog but also allows to automatically recognize similar individuals between two photos thanks to a deep learning artificial intelligence software.