The UN member states agreed on a treaty for protecting marine life in international waters that lie outside the jurisdiction of any country.
No country is responsible for the management and protection of resources on the high seas.
How important are the high seas?
A marine protected area (MPA) is defined as a geographically defined marine area that is designated and managed to achieve specific long-term biodiversity conservation objectives and may allow, where appropriate, sustainable use provided it is consistent with the conservation objectives.
The 30x30 pledge was made by the historic Kunming-Montreal Global Biodiversity Framework (GBF), at the COP15.