In the framework of the CPER project of the Nord – Pas-de-Calais region on Phaeocystis blooms, an interrogation has started to emerge concerning the historical aspects of these blooms. Research-ers remember that these blooms exist since the 1980s, and even perhaps the end of the 1970s, with strong and regular occurrences. This remains to be confirmed by further historical research. The question we address here is to determine, through historical research, what is the time of first strong apparition of these blooms in the region. The results obtained will be useful information in the framework of the debate concerning the origin of the phenomenon : is it natural or partially determined by anthropogenic effects? Available sources are not numerous, and it is not easy to find information. A systematic con-sultation of local press (from Calais and Boulogne-sur-Mer) has been done, for interwar years as well as for post-WW2 years. The first clear mention (with a photography) of foams that can be identified as a Phaeocystis bloom dates 1977. In this paper we present the sources consulted and the results obtained. We will also discuss the works of Giard, founder of the Maritime Station of Wimereux (in 1874), and the absence of any mention of coastal foam in his numerous writings at the end of the XIXth century.
