Although the Great Cormorant is certainly a migratory bird, this contribution discusses the increase of its wintering population in France as a "sociological invasion". From this perspective, it is the descriptions made by the populations concerned by the "too" large influx of this bird which will be studied here in a socio-anthropological context. This will enable interpretation and analysis of the events and choices relating to this question during the last 15 years in France. This approach enables understanding of the complex relations between the world of leisure fishermen and fish farmers and that of the authorities in charge of managing this situation. This study does not attempt to tackle the reasons for incomprehension of the scientific results on the part of the French public, but to examine the reasoning of French society when, on the particular subject of the management of wild species, it interprets and even refutes the data produced by scientists.
Eastern France, cormorant, extensive fish farming, biological invasion/sociological invasion, mentalities.