Coastal upwelling along the west coast of Sabah and its impact on coastal aquaculture management

Abstract

The aquaculture industry in Malaysia is currently growing at nearly 9 percent per year and is generating more than 250,000 tons of production per annum. However, little commercial scale aquaculture is present along the west coast of the state of Sabah. Few if any studies have been conducted to investigate aquaculture site suitability along the west coast of Sabah and the wider west coast of Borneo from an environmental or coastal management perspective. To determine the site suitability for marine aquaculture and other coastal resource users there needs to be an improved understanding of the physical, chemical, and biological characteristics of the coastal environment. One year of data collection including the long-term deployment of Conductivity, Temperature and Depth (CTD) sensors, and bi-monthly water column and seabed sediment sampling was undertaken to provide an indication if the coastal waters between Kota Belud and Kudat are suitable for marine aquaculture purposes. The site provided an analogy for much of the west coast of Borneo, especially the west coast of Sabah, due to similar oceanographic drivers in the region. Results indicated that during the NE monsoon period there is dramatic decrease in water temperature due to the upwelling of cold dense nutrient rich water onto the west coast of Sabah's continental shelf from deeper offshore areas of the South China Sea. This large change in temperature will likely rule out the potential commercial marine grow out of such species as Asian Seabass and perhaps Tropical Spiny Lobsters. Other species such as Cobia, Grouper and Snapper which have a wider tolerance for temperature change will likely be suitable but at times will be stressed due to magnitude of the observed changes. Such observations have ramifications in regard to site suitability for future resource consent applications for open ocean and coastal aquaculture along the west coast of Borneo. In summary the study highlights how physical processes can impact on resource use and development in a coastal setting.