Rusty french my footAccording to my very rusty French, 'Alerte' was a sort of rapid-response maritime aviation programme to which several types were designed (FBA, Paul Schmitt, etc).
I've done some further digging, and it seems (without guarantee, though) that these 'alerte' floatplanes were designed to patrol coastal waters nearing harbours to find out and drive off enemy submarines.
Read more HERE. Glad if it's of any help.