Earlier quoted context omitted.
(1) Informal norms among the fishermen as to how much fishing you should do. This system is not resilient to immigrants, who don't know the local norms (and may, not unreasonably, feel that the local norms already allot all of the fish to established fishermen), so fishing communities are often fiercely resistant to newcomers. "Informal" cultural norms operate as laws on a small scale, maybe a pre-industrial communit…
The ocean is all connected, but fish don't magically equalize their distribution by the law of fish gravity. If you double the number of ocean fishermen working out of Galveston, the supply of fish near Galveston will suffer. Cultural norms generally operate on a small group of people . In the modern day, it doesn't take very many people to catch a ridiculous number of fish. So depleting ocean fish is better handled…
That greatly depends on the type of fish and is not generally true. Many species of fish spend different parts of their lives at different locations. Tuna, salmon and many other pelagic fish travel pretty big distances.