Not owning the resource means there's little incentive to preserve it. Especially when you're competing with others to exploit it as effectively as possible. This is why there is little alternative in fisheries but to have vigorous regulation. A farmer who owns his own land will take care of it, but there is also a professional and personal side to the equation.

In my example of Tio Cheto, the waters of Tampa Bay were the commons, but the men who harvested those waters were also fishermen, they saw themselves primarily as fishermen. They were also shrewd businessmen, but they thought of themselves as watermen first, entrepreneurs second. Their tradition was one of respect for the resource; not a romantic and sentimental one, but because it represented their livelihood and the future and past of their families and of their colleagues. I'm sure that custom and self-policing as well as strong self-regulation evolved naturally in those communities, they would simply not tolerate those who abused the resource they all depended on.

Fisheries are a good laboratory to study this dynamic. As the stocks become scarcer, either through overfishing or natural causes, the financial pressure arises for the fishermen to become more efficient. They go into debt for bigger boats, better technology, they go further offshore, and they adopt fishing methods that are often destructive not only to their stocks but to the environment as a whole. All of these just aggravate the original shortages, and the problem feeds on itself. Soon, the industry is highly mechanized and very highly capitalized, and it is more dependent on outside financing and vulnerable to more organized corporate structures. It gets harder and harder for the individual entrepreneur to succeed, and the corporate factory ships manned by foreign crews soon start mining the offshore waters of everything that swims, while only the most profitable species are kept, the others simply thrown back dead over the side. There is an inverse correlation between the efficiency and the sustainability of the fishery. And one day, regardless of how much is invested, the fishery just collapses.

The parallels with our own agriculture, and with logging are obvious. Mining, of course, is non-renewable so it suffers different problems, but many of the same factors also apply.