Up in Alaska they fish for Pollock. It is a billion dollar industry. Now it is managed on a quota system and is one of the most, if not the most, sustainable fisheries anywhere. It didn't used to be that way.
It used to be run under what were called "olympic" or "derby" rules. The US Government set an annual catch allotment and then it was every man for himself. The results were disgraceful. Only 10% of the fish caught were turned into sellable products. Only the most valuable parts of the fish were kept and other parts, good, nutritious and sellable in their own right, but not as valuable, were chucked over the side. As sailors will recognize there is only a limited storage capacity on board a ship so it was desirable to keep the boat at sea as long as possible (you didn't want to fill your holds too fast) and come back with the most valuable cargo possible (fill up with roe and not fishmeal). Fish other than pollock were chucked at the very beginning and went back to the sea dead - the government didn't allow them being processed.
There were a lot of fish and there were a lot of boats chasing those fish. Based on the number of boats left after the quota system was imposed probably too many boats.
The companies employed a number of tactics, high grading - as described above was one. Keeping their fishing holes and tackle "secret" was another (like every other fisherman). They also put as many nets in the water as they could and scooped fish as fast as they were able. This scooping invariably resulted in the season closing early which, coupled with the really low yields, meant many boats struggled to pay their bills. If they had fished slower, processed more efficiently and co-operated more then more of them would have survived and the quota system would not have been imposed. But that wasn't how it worked.
The base line strategy was beggar thy neighbour. While there was fish in the water the purpose was to scoop them before the other guy could, even if you couldn't use them and had no intention of using them. You wanted to drive the competition out of business by denying them a revenue stream.