Are fisheries guilty? Are regulators and governments guilty? I think the guilty side are end-consumers, particularly in rich countries, people themselves and their lifestyle (ex: https://en.wikipedia.org/wiki/Pet_food#Impact ) note: I haven't eat a gram of fish or meat since more than a decade (mostly because I don't feel the need, being already full with local products: fruits, plants, legumes, rice
Telling every customer to change their habits (or just feel guilty) sounds good, probably has some effect but it's not enough. Controlling e.g. the much smaller number of producers is a lot simpler. Also, taxing the product (the end product that the guilty consumers can buy) may also work. Most likely you need to apply multiple measures at multiple points in this process.
E.g. I think convincing the customers works best in the long run and more like for general purposes. I.e. understand that you should consume less, use a smaller footprint in general, as you mentioned. But that doesn't necessarily easily translate to "don't buy tuna and milk". It's easier to translate it into "vote for the guy who promises to handle this case even if it means tax raises". And then you can simply go to the store and expect that whatever you see there is OK to buy at that price. Yes, tuna will be say 10x more expensive and thus you'll buy it less frequently (and maybe not feed it to your cat).