2024 October – What does the port visit data update mean for previously downloaded data?

In October 2024, Global Fishing Watch released two important improvements to port visit data to resolve errors.

1. Port visit data error

We identified an error affecting a small percentage of confidence 4 level port visits shown on vessel tracks in our APIs and Global Fishing Watch and TMT Vessel Viewer. Some false confidence 4 port visits were created when a vessel moved for >4 hours near anchorages but was not stopping at the anchorage directly. It was common to trigger false port visits in areas where anchorage density is high, for example, if a vessel is transiting through a river system slowly past many anchorages. The fix removed these instances of lower confidence port visits, meaning they are no longer available through the platform but accessible using Global Fishing Watch APIs. About 1.5% of port visits were impacted by this change.

For reference:

• Our Map displays only high-confidence port visits (referred to as confidence level 4)
• Our Public API allows users to access lower confidence levels of port visits.
• Our Data Download portal is not impacted by this fix since it still uses the previous data pipeline (more details on the latest pipeline version and updates).

2. Improved calculation of port visit location and accuracy

Previously, the location of a port visit was based on the average location of the port events that make up a port visit (see definition). Upon review, this could cause an inaccurate location in some instances. Now, we use the intermediate anchorage location, the first Port Stop or Port Gap if a Port Stop does not exist, to provide a more precise location estimate of the actual port visit by the vessel. 

For reference:

• Our Map: from October 2024, use the new way to calculate the location of a port visit.
• Our Public API: You can decide which calculation method to use depending on the version of the API dataset. By default API and gfwr, use the new calculation. For more details, please refer to the API dataset information in the API Portal.
• Our Data Download portal is not impacted by this fix since it still uses the previous data pipeline (more details on the latest pipeline version and updates).

This can be seen in the example vessel Yue Ma Yu 6888:

• After this change, the port visits are correctly shown in precise coastal location.
• Before this change the port visit was displayed on land.