Ports are essential facilities for the functioning of our globalised economy, as well as for the territories they supply. Monitoring port activity is therefore a relevant way of assessing the economic intensity they generate, and enabling regional analyses of their relative weight, their areas of activity and their development trajectories. However, comparative analysis of port activity is hampered by the variable quality and uneven distribution of the data produced by port authorities, which is far from being homogeneous, which makes comparative approaches difficult. In this paper, using vessel positioning data obtained through the Automatic Identification System (AIS), we propose a method for the extraction, quantification and qualification of port calls. We apply this method to a dataset in the Caribbean, covering the whole of 2019. Our method was able to describe the activity of 101 ports (in the sense of port areas) in the Lesser Antilles, by identifying 171,626 calls and their duration, by 5,907 ships of various type, size, age or flag. A comparison with the statistics published by a number of reference ports authorities and by the UNCTAD (United Nations Conference on Trade and Development) shows that the median difference of computed port calls is about 11%, thus validating the proposed approach. By qualifying the type of vessel that passes through port waters, according to its characteristics, this approach based on the number of calls makes it possible to observe the capabilities and the infrastructural quality deployed in the ports in terms of vessels, and, stemming from it, to develop the hypothesis of port vulnerability, that is a perspective for our future work.