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What is a vessel encounter?

What is a vessel encounter?
1

Encounters may indicate potential transshipment activity between two vessels that both appear in the automatic identification system (AIS) data source Our algorithm estimates an encounter event when two vessels were within 500 meters for at least two hours, and traveling at a median speed < two knots, while at least 10 km from a coastal anchorage.

We cannot know exactly what these vessels did during this encounter, but in many cases they are exchanging catch, supplies, or crew.

You can read more about transshipment behavior from our report or scientific publication.

In our map and carrier vessel portal, we focus on encounter events between carrier and fishing vessels. Interpret the data by clicking on a cluster of encounters or zooming in to the map. Click on any event of interest to view the vessels that encountered each other along with the date and time this took place. If available, click on the link to the carrier vessel portal for more information. In the carrier vessel portal, for both encounters and loitering events, the duration can be filtered between 1 hour and greater than 48 hours based on your preference. This filter can enable you to restrict possible transshipment events to those you consider more likely based on duration of transshipment events.

In a few limited cases for the map and carrier vessel portal, we include encounter events between purse seine support vessels and fishing vessels. Contact support@globalfishingwatch.org for more information.

In some specific API integrations, we send encounter events data for all vessel types. Contact support@globalfishingwatch.org for more information.

 

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