Offshore Capture Fisheries

Indonesia's marine waters exhibit exceptionally high spatial and temporal variability, with each marine region possessing its own distinctive oceanographic characteristics. This diversity results from the interaction of major ocean basins extending east to west—the Indian Ocean and the Pacific Ocean—as well as marginal seas extending north to south, including the South China Sea, Sulawesi Sea, and Java Sea, whose circulation is also influenced by waters associated with the Humboldt Current system off western Australia. From a climatological perspective, Indonesian waters are strongly affected by large-scale atmospheric circulation. The Walker Circulation drives the Southeast Trade Winds and Northeast Trade Winds across the Indian and Pacific Oceans, while the Hadley Circulation governs the Asian and Australian Monsoon systems.

Indonesia lies at the crossroads of these oceanographic and atmospheric processes, making its waters one of the world's most complex marine environments. The interaction and mixing of these processes create unique environmental characteristics in each marine region. Areas located closer to a particular oceanographic or climatic driver tend to be more strongly influenced by that process, resulting in distinct physical, chemical, and biological conditions throughout the Indonesian seas.

These unique marine characteristics are among the most important factors affecting offshore capture fisheries. For fishing industries, identifying productive fishing grounds remains a significant challenge because fish distribution is highly dependent on local environmental conditions. Large fish aggregations (fish schooling) are primarily controlled by three factors: environmental conditions that support fish physiology, the availability of prey species within the food web, and fish stock abundance, which is influenced by fishing pressure.

Critical environmental parameters include oceanic fronts where different water masses converge, regions with strong sea surface temperature gradients, specific mixed layer depths, thermocline thickness, upwelling zones where deep nutrient-rich water rises to the surface, and turbulent regions generated by divergent ocean eddies. These parameters continuously change over daily, seasonal, and interannual time scales, with each marine region exhibiting its own unique patterns of variability.