Uncovering the Effects of the Southwest Monsoon on Fishing Activity in the Indian Ocean with VIIRS Boat Detection Data

Abstract

In 2015, the Earth Observation Group (EOG) created the VIIRS Boat Detection (VBD) product, which is now employed by various fishery agencies to oversee fishing activities and ensure compliance with closures. VBD data offer real-time insights into the movements of fishing vessels, aiding in the detection of illegal fishing practices within restricted areas and intrusions into exclusive economic zones (EEZs). The Indian Ocean, a critical hub for global fisheries contributes over 14% of the world's wild-caught fish production. The fishing grounds in the Indian Ocean region are amorphous clusters, which depict cyclical patterns in the number of boat detections, corresponding to the monsoon season from June to September, and fishing restrictions imposed by the government. An exponential increase in boat detections was also observed since October 2016. Contrarily, the vessels detected at the anchorage are predominantly shipping vessels, and their temporal pattern shows less pronounced cyclical variation compared to fishing grounds. Employing the 'Pelt' algorithm to detect change points in monthly boat counts for the anchorage from 2012 to 2022 revealed a significant change in the average number of boat detections per month in October 2018. This study highlights the utility of VIIRS boat detection data in monitoring fishing activity and its response to seasonal and regulatory influences in the Indian Ocean, ultimately contributing to more effective fisheries management and conservation efforts.