I’m not aware of an industry where more subsidies have brought more sustainability. Certainly not the meat industry. Subsidies have brought mega-farms, more profits, and maybe lower prices. But not sustainability.

And for as long as we’re talking about raising carnivorous fish like salmon, I don’t see how it could ever be sustainable, given that carnivorous fish needs to eat food caught by very unsustainable fishing.

The only really sustainable aquaculture products are bivalves and seaweed: https://www.nature.com/articles/s41586-021-03889-2