The “Partner Port Charter” create a partnership between the Iroise Marine Protected Area (Iroise Marine Natural Park) and port areas of its territory. With this Charter, initiated in 2016, the MPA has implemented a model « Quality and Environnement Charter » process. It identifies potential environnemental impacts of port activities and defines priority areas and pollution reduction strategies. Since 2021, every 11 harbours of the MPA territory is commited to this charter. In 2010, a project based on the OSPAR protocol showed in the MPA a trend at the opposite of the national data : the main part of the macro-waste in Iroise Sea was of maritime origin (70 %). 13 % of that pollution was contributed by 'Industrial fishing', making it the most polluting activity. Macro waste from harbours became a target with a budget from of european projet (Preventing Plastic Pollution) and « France Relance » plan. The complementarities between these two key strategic tools permitted the MPA to implement a territorial policy to reduce plastic pollution at sea. The main pollution sources have been identified and characterized. We worked along with harbour managers and users to evacuate the current waste stock : 55 shipwrecks have been transported to a recycling center, 62 tons of macro-waste have been removed and we helped 3 fishing harbours to organise selective collection of used plastic fishing gear. The aim of these operations was to settle or support the implementation of a selective collection, transport and valorisation system for plastic harbour waste. To reduce and replace plastic, we work to use biosourced fishing nets and ropes experiments. As it is important to demonstrate the sustainability of these one-off aid measures over time, different steps of the project were combined with awareness raising, information and training of every category of stakeholders.