We have in previous chapters seen why fisheries have to be controlled: fish catches must be limited in order to avoid fish stock collapses, fishing mortality must be limited in order to maximize long-term yields, and the selectivity of fishing gear must be controlled in order to take advantage of fish growth or smooth fish catches over time. Any such control requires jurisdictional authority, first to set the rules and regulations and then to ensure that they will be followed, ultimately applying the powers of the sovereign state to punish violators as needed to deter infractions.

This mechanism works best within the borders of the sovereign state; the same state apparatus then sets the rules and punishes the violators. But fish stocks move about in the sea and are not easily kept within the limits of any single state. Many, and possibly the majority, of the stocks migrate between the waters of two or more states, and some into international waters where no state has jurisdiction except over boats flying their flag. There are even stocks that reside in international waters over their entire lifespan. Fisheries regulations, therefore, often require agreements between different states, none of which has power to impose regulations in the entire area where the stocks will be located over their lifespan. The enforcement of rules, including such as may have been agreed with other states, is much easier within a state's jurisdiction, however, than on the high seas outside the boundaries of any state.

In this chapter the development of the international law of the sea will be traced, from its freedom of the seas stage to the exclusive economic zone that is the premise of modern fisheries management. It is a fascinating story with unexpected twists and turns and, like all political sausage-making, not necessarily the perfect one for achieving optimal results. Be that as it may, the arrangement we currently have has necessitated wide international cooperation in fisheries management, some of which is formalized in regional management fisheries organizations given a somewhat special status by a fisheries agreement under the auspices of the UN.