The Distribution of Oceanographic Parameter Conditions in the Swordfish (Xiphias gladius) Fishing Ground in the Southern Indian Ocean off Java

Abstract

The Southern Indian Ocean off Java is one of the potential locations for catching swordfish. One crucial factor in improving fishermen's productivity is the availability of information regarding the characteristics of waters related to potential fishing areas. This research aimed to determine the distribution conditions of several oceanographic parameters such as sea surface temperature, salinity, chlorophyll-a, and surface currents using remote sensing data at the swordfish (Xiphias gladius) fishing ground in the Southern Indian Ocean off Java. This research was conducted from April 27, 2022, to December 12, 2022, in the Indian Ocean. Data for several oceanographic parameters were obtained from the data.marine.copernicus.eu website from April 2022 to December 2022, and the coordinates of the swordfish (Xiphias gladius) fishing ground were obtained from KM Lulu Marina 08, which operates in WPPD 57. Data from data.marine.copernicus.eu are the result of reanalysis methods developed by the Copernicus Marine Service (CMS) using multisensor satellite images data such as MODIS-AQUA, NOAA20-VIIRS, NPP-VIIRS, and Sentinel 3A-OLCI. The spatial resolution of the data was standardized to 0.001 degrees using resampling techniques with B-Spline interpolation. The highest sea surface temperature (SST) at each fishing ground was recorded in April 2022 at the fishing ground ST 1, reaching 27.52°C. The lowest SST was observed in November 2022 at fishing ground ST 6, measuring 21.70°C. The lowest salinity values at each fishing ground were recorded in June 2022 at fishing ground ST 1, measuring 34.09 psu, while the highest salinity values were found in April 2022 at fishing ground ST 6, measuring 35.38 psu. The lowest chlorophyll-a concentration values at each fishing ground were recorded in December 2022 at fishing ground ST 6, measuring 0.062 mg/m3, while the highest concentration values were found in September 2022 at fishing ground ST 6, measuring 0.357 mg/m3. The lowest catch was recorded in September 2022, with only 2 fish caught, while the highest catch was recorded in November 2022, with a total of 42 fish caught. The optimal swordfish catch rate falls within the range of SST 23.47-24.74°C, salinity 34.45-34.78 psu, and chlorophyll-a concentration in the range of 0.079-0.124 mg/m3.