Dynamics of Thermal Fronts Distribution in the Flores Sea, Indonesia: An implication for locating potential skipjack tuna fishing ground

Flores Sea is one of the most productive fishing grounds within the Indonesian Fisheries Management Area 713 which has the unique physical structures such as topographic feature, the seasonal wind driven upwelling, and also the dynamics of frontal patterns. The purposes of this study were to map the dynamic spatial of the thermal fronts in the east and the second transition seasons, and to describe their implications to the skipjack fishery. We applied the satellite data of sea surface temperature (SST) for the period of June-October 2018 with spatial and temporal resolutions of 0.04 degree latitude and longitude and monthly, respectively. For fishery data, we used sampling data of skipjack tuna fishing ground distributions during this period. The thermal fronts were estimated using a Single Image Edge Detection (SIED) algorithm and the available fishing ground data were superimposed on the SST frontal maps. The results showed that the spatial distribution patterns of thermal fronts along Flores Sea tended to be different every month. However, the thermal fronts were consistently detected throughout the study period. Skipjack tuna fishing grounds started to develop in the eastern area of Selayar Island in June (before upwelling event) and reached a peak in October (after upwelling). During these months, the skipjack fishing grounds well formed around the thermal fronts with the distance of 0-40 km. It implies that the formation of the thermal fronts especially after upwelling gives a significant contribution on the development of skipjack fishery in the Flores Sea.