Use of Space-Time Cube Model and Spatiotemporal Hot Spot Analyses in Fisheries-A Case Study of Tuna Purse Seine

Katsuwonus pelamis, or skipjack, is a vital resource in purse seine fishing across the Central and Western Pacific. Identifying skipjack distribution hotspots and coldspots is crucial for effective resource management, but the dynamic nature of fish behavior means these spots are not constant. We used Chinese fishing logbook data from 2010 to 2019 to analyze skipjack resource hotspots and coldspots in a space-time cube. The study revealed 13 spatiotemporal patterns in skipjack Catch per Unit Effort (CPUE). Hotspots (36.53%) were concentrated in the central area, predominantly showing oscillating hotspots (21.25%). The significant effect of the eastern oscillating hotspot continues to be enhanced and extends to the east. Coldspots constituted 63.47% of the distribution, mainly represented by intensifying coldspots (25.07%). The no-pattern-detected type (10.53%) is distributed between coldspots and hotspots. The fishing grounds exhibited longitudinal oscillations of 3 degrees-6 degrees and latitudinal oscillations of 1 degrees-2 degrees. The spatial autocorrelation of cold and hot spot distribution was strong, and the spatiotemporal dynamic changes in skipjack resources were closely related to the El Nino-Southern Oscillation (ENSO) phenomenon. Notably, during 2011-2016, hotspots exhibited an eastward expansion trend, which continued from 2017-2019 due to the influence of fishery management measures, such as the Vessel Day Scheme (VDS) system.