Support measures
Install information boards at beaches about aquaculture (and fisheries) waste (how it does look like). Motivate the public to collect this kind of waste and to bring it to a municipal central location or directly to the owner. In parallel set up a sea-basin or international registration system to report waste: An easy to access online platform should give people information on the collected items (i.e. QR-code, number, etc.).
Technical support
Relevant type of aquaculture:
Relevant sea basin:
Relevant stage: