[dark_lord]

Luckily this kind of thing tends to be self correcting, when there aren't enough fish to catch profitably we cut down on the catches (already are with many breeds we're now farming) this gives that fish time to recover population, which will eventually result in them being profitable for massive fishing again.

There is truth to what you say, but you are oversimplifying. What happens when you have government subsidized fishing? Then the fishing fleet fishes even in depleted waters, which can drive some species to extinction. Japan, for example, which does not tolerate unemployment well, may happily keep their fleet going using drift nets until vast areas of the ocean are turned into deserts. And they are not the only country that would prefer to keep their fishing fleets employed regardless of the catch. The PRC, for example, uses some (many) of its fishing vessals for intelligence gathering.

[discostu]

My understanding is the spy-trawlers don't catch much fish. What'll happen from Japan's activity is that they'll make the area unable to support fish and the fish will stop coming. The ocean's big, the Pacific is almost an entire hemisphere, lots of place for fish to hide. Subsidizing might tilt the scale but eventually even that becomes too expensive. We might lose a couple of species but that too is the natural course of things, extinction happens.