Although researchers have investigated the impact of Indian Ocean Dipole (IOD) phases on human lives, only a few have examined such impacts on fisheries. In this study, we analyzed the influence of negative (positive) IOD phases on chlorophyll a (Chl-a) concentrations as an indicator of phytoplankton biomass and small pelagic fish production in the eastern Indian Ocean (EIO) off Java. We also conducted field surveys in the EIO off Palabuhanratu Bay at the peak (October) and the end (December) of the 2019 positive IOD phase. Our findings show that the Chl-a concentration had a strong and robust association with the 2016 (2019) negative (positive) IOD phases. The negative (positive) anomalous Chl-a concentration in the EIO off Java associated with the negative (positive) IOD phase induced strong downwelling (upwelling), leading to the preponderant decrease (increase) in small pelagic fish production in the EIO off Java.

We analysed the variability of sea surface temperature (SST) and chlorophyll-a concentration (Chl-a) in the eastern Indian Ocean (EIO). We used monthly mean Chl-a and SST data with a 4-km spatial resolution derived from Level-3 Aqua Moderate-resolution Imaging Spectroradiometer (MODIS) distributed by the Asia-Pacific Data-Research Center (APDRC) for the period 2002–2017. Wavelet analysis shows the annual and interannual variability of SST and Chl-a concentration in the EIO. The annual variability of SST and Chl-a is influenced by monsoon systems. During a southeast monsoon, SST falls while Chl-a increases due to upwelling. The annual variability of SST and Chl-a is also influenced by the Indian Ocean Dipole (IOD). During positive phases of the IOD (2006, 2012 and 2015), there was more intense upwelling in the EIO caused by the negative anomaly of SST and the positive anomaly of Chl-a concentration.

No abstract

Kami menggunakan data harian sensor satelit Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) untuk pemetaan distribusi kapal-kapal ikan yang menggunakan cahaya untuk operasi penangkapan ikan selama periode 2015-2017 di Laut Jawa. Tujuan dari penelitian ini adalah untuk menganalisis perbedaan distribusi kapal-kapal ikan yang menggunakan cahaya untuk operasi penangkapan ikan antara fase  bulan terang dan fase bulan gelap. Survei lapangan dilakukan untuk mengetahui jenis kapal ikan yang menggunakan cahaya lampu untuk operasi penangkapan ikan. Kami menganalisis perbedaan distribusi kapal penangkap ikan antara bulan terang dan bulan gelap di Laut Jawa. Hasil penelitian menunjukkan bahwa jumlah rata-rata kapal penangkap ikan menggunakan lampu untuk operasi penangkapan ikan di fase bulan terang badalah 230 unit sedangkan fase bulan gelap adalah 1.118 unit. Analisis statistik uji-t menunjukkan ada perbedaan yang signifikan secara statistik antara rata-rata jumlah kapal ikan pada fase bulan terang dan bulan gelap.

We analyzed the distribution of Purse seine fishing vessels using fishing lamps derived from the Day/Night Band Visible Infrared Imaging Radiometer Suite (DNB-VIIRS) sensor and Vessels Monitoring System (VMS) platform in the Java Sea. The data of fishing vessel distribution derived the DNB-VIIRS sensor and VMS platform was provided by NOAA Center for Environment Information and Global Fishing Watch respectively. The intensity of lights during the fishing operation was measured by a lux meter. The fishing vessel types that used light during fishing operations were small (< 15 units lamps) and large vessels (>15-unit lamps). The intensity of light in the big vessels (> 2,000 Lux) was higher than the small vessels (< 2,000 Lux). The average number of fishing vessels operating during the Southeast monsoon were more than those of the Northwest monsoon. The distribution of fishing vessels derived from the DNB-VIIRS sensor has a similar pattern with the VMS platform. Generally, the fishing vessels are concentrated along the southern coast of Borneo but in the Northwest monsoon shift towards the northwest of Java approaching the island of Sumatra.