International audienceFrom May, 31st to June 3rd, 2017, an international conference was held at the Cerisy-la-Salle International Cultural Center, entitled “Aquatic animals and Monsters of the Northern Seas (Imagination, knowledge, exploitation, from Antiquity to 1600)”, organized by the Centre Michel de Boüard – Craham (UMR 6273, Université de Caen Normandie – CNRS). The introduction to the proceedings of this conference presents first the scientific context, and the research programs Dyrin (history of the Nordic fauna in the Middle Ages) and Ichtya (history of knowledge on fish from Antiquity to the Renaissance) in which the organizers of the conference are involved. A quick summary presents the state of art about studies on the history o...