Theo, while the solutions you propose are worthwhile — IMTA (integrated multi trophic aquaculture) systems, in my opinion, are barely beginning to explore their potential for both productivity and eco-system regeneration.

The solution that you seemed to have skipped is the establishment and protection of Marine Protected Areas where fishing and other activities are strongly or completely restricted.

There is a great deal of data that by protecting areas of the ocean the overspill in fish in the surrounding areas increase overall fishing yields.

https://www.un.org/Depts/los/consultative_process/documents/6_roberts.pdf