Points 2 and 3 kind of contradict themselves though, as China doesn't have access to deep sea (at least until the invasion of Taiwan or if China manage to take control of their claimed share of South China Sea).

You can farm fish outside territorial and exclusive economic zone waters. But in any event China has substantial EEZ waters: https://www.marineregions.org/gazetteer.php?p=details&id=848... Taiwan isn't much of a hindrance. For one thing, the Strait is 100 miles wide. And China's coast is much, much longer than Taiwan.

They are doing both landlocked and mobile deep-sea methods farming with success. In typical Chinese fashion as they have done with Fruit and other food productions, I wouldn't be surprised if they could scale it 10x within 5 years. I doubt it will take away Norway's supply to Japan in the short term due to quality and trust issues. But export to China may be lowered.

China has the world’s largest distant-water fishing fleet, and Chinese vessels fish far beyond China's coastal waters like in South America, West Africa, Indian Ocean.

That's an interesting fact but that does not tell me anything about the possibility it has of raising salmon in its own waters