Reports have come in from some Yachts that have been stopped by the Gendarmerie Maritime for not having lights on the buoyancy aids used by their PWC guests..
It is believed that this regulation was introduced after the death of a jetskier near Saint-Mandrier in 2014 (read the report below).
http://www.europe1.fr/faits-divers/le-corps-de-la-jeune-femme-tombee-de-son-jet-ski-retrouve-2182313