A typical capitalist analysis.

It totally ignores what really matters when harvesting a natural resource, namely, the biology of the organism. What is really important is the life cycle of the fish, not some accountant bullshit. Where do they spawn? In what season? Doesn't it make more sense to harvest them after they've reproduced than before, so there will be fish next year? At what age (size) do the fish spawn? Catching them while they've not had a chance to do so would rapidly deplete the stock, so it would make sense to set size limits or regulate net mesh. And what about the method used to harvest them? Some techniques, like trawls, destroy the bottom ecosystem so that you not only remove the fish, but everything they depend on and not only is the catch lost but the ability of the environment to produce more is crippled, sometimes irreparably.

Most fish stocks, properly managed, can recover from quite vigorous harvesting, and provide high yields year after year if the fishermen are regulated based on sound fisheries science and conservation practices. There is no need to stop eating fish, we just need to fish more intelligently. Not surprisingly, subsistence fisherman often do this subconsciously. They fish to support themselves, but it is a dangerous and expensive operation so there are incentives not to overfish. They tend to fish as much as they need to earn a good living, then stop. It provides a lot of employment for the number of fish taken. That may be inefficient, but it favors small businessmen and a thriving local industry, which is good, isn't it? Yields are smaller, prices higher, but the fishery is sustainable.

They also know the life cycles of their catch and self-regulate. Individual crabbers in Florida used to routinely throw back the females so there would be crab the following year. When seafood restaurants and fish wholesalers developed a lucrative commercial market for shedders (molting females just prior to their reproductive season) it became a rout and regulations and draconic enforcement had to be introduced to save the species from extinction.

It all changes when you go from use fishing to fishing for market.
Now, you never get enough catch, and when it starts declining, you borrow money and get bigger boats and bigger, finer mesh nets and go farther out and deeper down and fish longer seasons with fancy electronics and you become "more efficient". Family fishermen are small businessmen and will gladly cooperate to preserve their resource and their beloved lifestyle. When the big capital-intensive corporate-owned factory boats come in they just mine the ocean until its desolated, then they move on.

Individual fishermen, like farmers who love their land, are not likely to overstress their resource and threaten their own livelihood. They will gladly accept regulation if it is done for their benefit and the long term viability of the fish stock. But once they start borrowing money and making big investments in boats and gear and fuel, they become slaves to the banks and are under great pressure to increase yields. This tends to drive out the small operators and leads to bigger enterprises (boats or farms), operating on razor thin profit margins. The pressure will be on to just become more and more "efficient".

The most efficient fishermen in the world are those Asian factory ships that are now systematically mining the world ocean and have led to declining fish stocks all over the planet. The problem with the free market model is that fishermen don't make fish, they remove them. The biosphere does not participate in the economic calculations, it just bleeds to death.