Sometimes the downloadable fishing effort data for an individual MMSI adds up to more than 24 hours per day. This is due to how Global Fishing Watch assigns time to AIS positions, which is based on the time since the vessel’s previous AIS position. However, due to uncertainty, we never assign a single position more than 24 hours. Sometimes a vessel’s first AIS position of the day will be assigned time from the previous day, resulting in a vessel’s total activity for a day exceeding 24 hours (but not to exceed 48 hours).
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- Why do some MMSI’s downloadable fishing effort data add up to more than 24 hours?