Definition
AIS is the automatic identification system for ships: a transponder that broadcasts by radio, every few seconds, the vessel’s identity, position, course and speed. It was created to prevent collisions and is now the basis for tracking maritime traffic.
Under the international SOLAS convention it is compulsory for ships of 300 gross tonnage or more on international voyages and for all passenger ships. The signals are received by other ships, coastal stations and satellites, which makes it possible to follow the world fleet almost in real time.
Those positions are used to produce statistics that did not exist before: daily calls at each port, transits through straits and canals, or estimates of the cargo each ship carries according to its type and draught. That is what IMF PortWatch does, the source of the figure that accompanies this page. They are estimates, not records from customs or from the port authorities.
The figure · 25 September 2026
Estimated cargo · Spanish ports (7-day average)
1.04 million tonnes a day
Daily calls (7-day average)
122 calls a day
Transits through the Strait of Gibraltar (7-day average)
133 transits a day
Spanish ports tracked
38 ports
Daily activity of Spanish ports by satellite
Spanish ports handled an average of 1.04 million tonnes a day in the week ending 25 September 2026, according to IMF PortWatch’s satellite estimate, 9.6% less than in the same week of 2025. They recorded an average of 122 calls a day.
The full ranking, the trend and the table are in the indicator Daily activity of Spanish ports by satellite. To explore the data in detail, see Maritime Radar.