Mapping and Tracking Nighttime Fishing Activities within Japan EEZ using VIIRS Boat Detection

Wataru Takeuchi*, Yiwei Huang

Abstract

Nighttime fishing is one of the most efficient methods used in modern fisheries. About one quarter of Japanese annual sea surface fishery production is caught by fishing boats that use powerful light to attract fishes, based on their phototaxis. This study explored the potential application of the nighttime boat detection data, extracted from the Visible Infrared Imaging Radiometer Suite Day/Night Band (VIIRS DNB) images, for monitoring fishing activities. Nightly boat detection data from 2016 to 2020 were used to examine spatiotemporal patterns of nighttime fishing activities. Using Hierarchical Density-based spatial clustering of applications with noise (HDBSCAN), 127 clustered area were identified. The clustered area had different seasonality, reflecting differences in lighting sources and fishing methods. Within 127 clustered areas, 97 areas were identified as potential fishing area based on their seasonality and vessel density distribution inside. The results of spatiotemporal analysis showed good consistency with pelagic fish distribution in the East China Sea, Japan Sea and Pacific. Monitoring spatiotemporal pattern changes of fishing activities by firstly identifying high vessel density areas from VIIRS Boat Detection data is demonstrated to be an effective approach.

Keywords: Nighttime Fishing; Remote Sensing; VIIRS Boat Detection

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