One of the fundamental features of Indonesia is that it is an archipelagic state. Large-format maps of Indonesia usually show the straight baselines that join the outermost points of the outermost islands, thereby enclosing within a single entity the thousands of islands that make up the country and all the ‘archipelagic waters’ within the baselines (see Map 2.1). These maps also show the territorial sea that, except in a very few areas, extends 12 nautical miles out from these baselines and the exclusive economic zone (EEZ) that in most areas extends 200 nautical miles out from these same baselines. As a consequence much of the territory of Indonesia is made up of water. More precisely, water makes up about 58 per cent of the total area of 4.5 million square kilometres over which the state asserts its sovereignty, namely the land and water within the baselines and the territorial sea extending out from the baselines. The country's EEZ, within which the government exercises sovereign rights over all the living and non-living resources in the water and both on and under the seabed, gives the government limited jurisdiction over a further 5.4 million square kilometres. The result is a massive country Indonesia is the world's largest archipelagic state and has the third largest EEZ in the world.

Indonesia has, it must be noted, a number of disputes with its neighbours over the precise boundaries of some of its claims to maritime territory. In the most prominent of these, Indonesia and Malaysia both claim jurisdiction over a section of sea off the east coast of Kalimantan known as the Ambalat block; in 2005 tensions between them reached a peak when naval vessels from the two countries confronted one another in this area. Leaving aside disputes over what are, in relation to the whole, small patches of sea, however, the lines on a standard map of Indonesia are accepted by its neighbours. These lines, moreover, conform to the principles set out in the United Nations Convention on the Law of the Sea, ensuring that Indonesia's status as an archipelagic state has international recognition.

The Japanese occupation of most of Southeast Asia from 1942 to 1945 had a devastating effect on fishing just as it did on most other economic activities. By the end of the war a great deal of equipment — boats, fishing gear, and ice plants — had been destroyed or badly damaged, imports of twine, nets, sail cloth, hooks, wire, and other materials needed for fishing had been cut off, transport and marketing systems had been disrupted, and the purchasing power of consumers had been greatly diminished. There is no direct way of measuring the course of catches during this period, but there are many indicators of the scale of the collapse. According to official statistics, fish landings in Malaya in 1946, when the industry had already begun to recover, amounted to 46,000 tons, as compared to an average of 85,000 tons in 1936–40. The number of trawlers operating in Manila Bay fell from seventy-one in 1940 to two by the end of the war. At Estancia subsistence fishing continued during the war, but commercial fishing came to a halt. Nearby on tiny Botlog Island “fishing activities … experienced a drastic change, since [the people] had to hide from time to time”. At Perupok fishing was severely disrupted, as the Japanese took people away (“the men with promise of work and the women as prostitutes”), paid little or nothing for the fish they wanted and appropriated much of the local rice harvest. The long-distance trade in fish products came almost to a standstill. Exports from Thailand fell from 17,000 tons in 1941 to 26 tons in 1945. The collapse in the long-distance trade meant that consumption of fish in areas such as Java and the west coast of the Malay Peninsula that had long depended on imports fell much more than the drop in local catches would suggest. At the same time the trade in salt, essential for the preservation of fish not consumed immediately after landing, virtually disappeared during the occupation. Exports of salt from Thailand fell from 139,000 tons to 2,000 tons between 1941 and 1945. Presumably the importation of salt from across the Indian Ocean ceased altogether right at the start of the war.

The Industrial Revolution generated a vast array of inventions that could be applied to the capture of fish. The most obvious of these was mechanical power. A boat powered by a steam engine or an internal combustion engine could be used to tow non-motorized boats to the fishing ground and to carry catches to market while the fishing boats remained at sea. When the fishing boat itself had mechanical power, the engine could supplement or even take the place of wind and muscle to carry fishers to their prey and power the boat as a fishing gear was being set or towed behind the boat. Mechanical power made it possible to think of using old fishing gears on a larger scale, modifying old fishing gears or even introducing new ones to take greater advantage of the potential it created. At the same time more efficient pumps, more powerful forms of lighting, and more powerful explosives created still more possibilities for exploiting marine resources. There was nothing automatic about the adoption of these new technologies, however. Whether fishers or investors made use of new technology largely depended on whether it brought sufficient profits to outweigh the cost of acquiring and operating it. This in turn depended on how much could be caught with the new technology, the size of the market, and the price of the product in that market. When an official suggested to a fisher in Kelantan “that he should buy an outboard motor which was not very dear” so that he could return home with his catch early in the morning rather than having to wait until noon for the sea breeze to come or to battle a headwind, “he told me he had insufficient money to purchase one”. On the other side of the Malay Peninsula one fish dealer experimented with a motorized fish carrier but gave it up after a year “as not sufficiently remunerative”, while another whose “motor boat was not decked and so dangerous when the sea grew even moderately rough” abandoned the experiment after a few months. In these circumstances states often took the lead in experimenting with new technologies or supporting private investors who wished to do so. The extent to which they did this varied greatly, however.

The late 1970s and early 1980s may be taken as an important turning point in the history of the extension of the frontier of fishing in Southeast Asian waters. It was at this time that the Indonesian government banned trawl fishing in most of the sea under its jurisdiction and that governments throughout Southeast Asia claimed their offshore waters as exclusive economic zones. Both events, arising as they did out of conflict over access to living marine resources, indicate that the period of freewheeling extension was ending. During the 1980s and into the 1990s the demand for fish products continued to grow rapidly. The population of Southeast Asia — the single most powerful source of demand — grew at 2 per cent a year to 480 million in 1995, while living standards rose as the economies of many countries, particularly Singapore, Malaysia, Thailand, and Indonesia, were restructured towards the export of manufactured goods. At the same time, the economic success of Taiwan and Hong Kong and the emergence of a class of rich business people in the People's Republic of China renewed the centuries’ old demand from China for the marine exotica of Southeast Asia, and the markets for tuna and shrimp continued to grow in Japan, North America, and Europe. At least in the short term this growing demand was matched by increasing catches. Between 1980 and 1997 nominal fish landings rose from 5.8 to 11 million tons, contributing (along with supplies from freshwater sources, aquaculture, and imports) to a general increase in the per capita supply of fish to the people of Southeast Asia. There were, however, limits to how much the sea could yield to meet the ever-increasing demand. During the 1990s total landings increased less rapidly than they had during the 1980s. In the Philippines, the first country to take part in the fish race, landings ceased to increase during the 1990s, while in Thailand, the second country to join the race, they increased much less rapidly than they had during the previous three decades. This slowing took place even though, as we shall see, large-scale operators in both countries landed large quantities of fish caught in the waters of other countries.

In 1850 Southeast Asia had a population of just forty million or so. The greatest concentrations of population were in Java (with perhaps a quarter of the total), Madura, Bali, the rice basins of the Menangkabau highlands of west Sumatra, the dry zone of the Irrawaddy, the flood plain of the Chao Phraya, the coast of Vietnam, Luzon, and southwest Sulawesi. There were pockets of population in the Straits Settlements of Singapore, Penang, and Malacca and numerous small sultanates in the island world from Aceh in the west to Ternate in the east. In contrast, large sections of Southeast Asia such as much of the area along both sides of the Straits of Malacca, most of Borneo, and most of the eastern island world were very sparsely populated. The great majority of the people of the region were peasant farmers, growing rice and other food crops for their own consumption and usually producing food and other goods for their overlords as well. A very small proportion of the population lived in cities and towns or worked in mines and plantations. The people of the region lived within or on the fringes of a very large number of political units in which power was, at least from our vantage point, highly decentralized, though less so in the few areas then under colonial rule such as Java, the Straits Settlements, Luzon, and the Visayas than in most of the rest of the region. In this world of scores of polities and thousands of islands a powerful unifying influence was the sea. It was by sea that people travelled long distances, and it was by sea that nearly all the long-distance trade was conducted, not only within the region but also with China, India, and Europe. Trade in sea-going sailing vessels and, by 1850, a tiny number of steamships was the lifeblood of such port cities as Singapore, Batavia, Surabaya, Makassar, and Manila.

And it was the sea that provided animal life that people exploited both for food for themselves and for products that they could trade with others. For many people the capture of marine life was not their main activity. They were primarily agriculturalists and fished when planting and harvesting did not demand their full attention. For others, however, fishing was their main source of livelihood.