Each fisherman has an incentive to take out as many fish as possible, since any fish left will only be taken by the fisherman behind him. So a sufficient breeding stock is not left, and the population collapses. The only solution is some kind of international governmental regulation to limit the catch to sustainable levels. Fish is a very efficient protein source, and is being produced through a type of farming called aquaculture . Catfish, trout, and salmon are among the major species being produced this way.
Fish is a major part of the diet in poorer countries because it is cheap.
Much of the use of forests is for paper , but this does not use virgin forest any more, but trees that are grown on tree farms. This is called silviculture . In the industrial world paper, construction, and furniture are the major uses. But in poorer countries wood is used as a fuel. Deforestation is a major problem, since it may contribute to global warming both by the burning of trees and by the fact that growing trees remove CO2 from the atmosphere.