By Graham Pilgrim, Emmanuelle Guidetti and Annabelle Mourougane, OECD Directorate

PARIS - Rising uncertainties and geo-political tensions, together with more complex trade relations have increased the demand for data and tools to monitor global trade in a timely manner. At the same time, advances in Big Data Analytics and access to a huge quantity of alternative data – outside the realm of official statistics – have opened new avenues to monitor trade. These data can help identify bottlenecks and disruptions in real time but need to be cleaned and validated.

One such alternative data source is the Automatic Identification System (AIS), developed by the International Maritime Organisation, facilitating the tracking of vessels across the globe. The system includes messages transmitted by ships to land or satellite receivers, available in quasi real time. While it was primarily designed to ensure vessel safety, this data is particularly well suited for providing insights on trade developments, as over 80% in volume of international merchandise trade is carried by sea (UNCTAD, 2022). Furthermore, AIS data holds granular vessel information and detailed location data, which combined with other data sources can enable the identification of activity at a port (or even berth) level, by vessel type or by the jurisdiction of vessel ownership.

For a number of years, the UN Global Platform has made AIS data available to those compiling official statistics, such as National Statistics Offices (NSOs) or International Organisations. This has facilitated the development of new methodologies, for instance the automated identification of port locations (Irish Central Statistics Office, 2022). The data has also been exploited by data scientists and research centres to monitor trade in specific commodities such as Liquefied Natural Gas (QuantCube Technology, 2022) or to analyse port and shipping operations in a specific country (Tsalamanis et al., 2018). Beyond trade, the dataset has been used to track CO2 emissions from the maritime sector (Clarke et al., 2023).

New work from the OECD Statistics and Data Directorate contributes to existing research in this field in two major ways. First, it proposes a new methodology to identify ports, at a higher level of precision than in past research. Second, it builds indicators to monitor port congestion and trends in maritime trade flows and provides a tool to get detailed information and better understand those flows.

A new OECD AIS Tracking Dashboard lets users visualise key indicators on ports and maritime trade, and is available here ( .

Indicators still need to be refined, by complementing the AIS database with additional data sources, but already provide a useful source of information to monitor trade, at the country and global levels. Two indicative examples are provided below.

Signs of a stabilisation in maritime trade for 2023

The number of vessels and port capacity – the sum of Dead Weight Tonnage (DWT) of all the vessel visiting ports – provide some indication of trends in maritime trade. Although the indicator levels cannot be interpreted as levels of trade flows, an increase is likely to coincide with a rise in maritime activity, which in turn is positively correlated with global trade. As such, these data can provide timely indicators of sudden changes in global trade, together with information on the type of vessels.

Changes in estimated maritime export and import volumes in 2023 display some common features across most developed economies, suggesting little growth on average over the year in global trade. Though volume changes can reveal a trend, they do not account for what is traded and do not give a precise estimate of the value of those flows, meaning these numbers need to be interpreted with caution.

Volume measures of containers point to a stabilisation, many countries in Europe and in America experienced a slowdown in imports in the latter part of the year while exports have remained broadly stable or picked up slightly during that period (Figure 1). Developments in Asia differed from what was observed for Europe and North America. In particular, there are indications that exports, via containers, have continued to expand and imports via bulk dry vessels have increased in China. Imports in the region have stayed flat.

Vessels rerouting from the Suez Canal to the Cap of Good Hope following the Houthi attacks

AIS information can help cast light on topical issues in a very timely manner. For instance, the Houthi attacks on vessels since October 2023 have restricted container ships heading to Europe via the Suez Canal as they avoid passing the Bab el-Mandeb Strait and reroute via Southern Africa and the Cape of Good Hope. This has raised concerns of lengthening delivery times for supplies, increasing supply-chain bottlenecks and rising prices.

Tracking information from AIS, using a simple approach to estimate traffic at choke points, can help assess the magnitude of these effects, provide detailed information on the type of the vessels which would be most affected and monitor the situation in quasi real time. A caveat is that vessels may switch off their emitters for fear of being spotted, which can lower the reliability of AIS signals.

The switch in vessel routes since the first Houthi attack on 19th October is clearly visible, with a dramatic fall in daily traffic in the Red Sea and a mirrored rise in the Cape of Good Hope (Figure 2). All types of vessels altered their routes but comparing the number of vessels in January 2024 from the count in January 2023, the number of containers passing by the Suez Canal was halved.

Like many ‘Big Data’ sources, the AIS was not originally intended for statistical purposes, making it necessary to acknowledge and attempt to resolve some of its shortcomings. A number of techniques were applied to address some of those. However, additional research will be needed to improve further the exploitation of this rich source of information.