Since the 200-mile exclusive economic zone became nearly universally established in the late 1970s, fisheries management by catch quotas has become increasingly widespread. The 200-mile zone was an important precondition, because a limit on total catches from a fish stock requires control over the boats fishing that stock. When most fisheries took place outside national limits, fish quotas would have required acceptance by all nations that engaged in the fishery. If those that participated in a fishery on the high seas had agreed on a total fish quota, this could have been challenged by newcomers, who could have entered the fishery by virtue of free fishing on the high seas. Successful management by those who at one point in time participated in a fishery would have made that type of challenge all the more likely. In this chapter we shall discuss fisheries management by catch quotas, its advantages and challenges and what the main alternatives are.

Even in cases when a fish stock is entirely within the economic zone of one country, setting a total quota can be a challenge; there are often distinctly different interest groups involved, much like different countries fishing the same stock. Satisfying everyone's demands would most probably mean that the total quota would be much too high, threatening depletion of the fish stocks. Cutting through such competing claims can be difficult enough for a single government, and doing so when different countries are involved more difficult still, as the legal enforcement apparatus of the nation state cannot be relied upon; no country has jurisdiction on another's territory. The issue is even less tractable for stocks that migrate into the high seas, for reasons discussed in the previous chapter; it is more challenging to cooperate when the number of participants is large, let alone indefinite, and enforcement is more difficult on the high seas, where no country has jurisdiction except flag states over their own boats. Nevertheless, control by fish quotas has become quite widespread, even for fish stocks that are shared between a number of countries, including those that straddle into the highs seas.