According to a study, there is no publicly available data for around three quarters of all trips by larger fishing vessels. This is the result of an analysis of satellite images from the period 2017 to 2021. The activities discovered could provide clues to possible illegal fishing, writes a research team led by Fernando Paolo from the non-profit organization Global Fishing Watch in the journal “Nature”. For comparison: Only about a quarter of all trips on transport ships cannot be tracked.
“More than a billion people rely on the sea as their main source of food, and 260 million people are employed in global marine fisheries alone,” write the study authors. However, many stocks of marine life are considered to be overfished, including through illegal fishing.
Since 2000, the Automatic Identification System (AIS) has been a binding standard of the International Maritime Organization (IMO), which is intended, among other things, to improve the safety of maritime transport. However, not all vessels are required to use AIS devices as regulations vary depending on country, vessel size and activity. An AIS system can also be switched off, for example to conceal illegal fishing.
To get a more complete picture of human activity at sea, Paolo and colleagues analyzed 67 million sections of satellite images. From this, the team created maps that have a resolution of 15 to 20 meters and on which they were able to identify various objects on the oceans – from ships to oil rigs to wind turbines. By comparing them with the publicly available AIS data, the authors then identified those ship sightings in which AIS systems were not used.
Industrial fishing in Asia is more extensive
If you only look at the AIS data, fishing activities off the European coasts are about the same as those off the Asian coasts. However, satellite data shows that industrial fishing around Asia is significantly more extensive. Accordingly, Asian fishing fleets account for around 70 percent of all fishing vessels worldwide. In the waters around China alone, these ships account for around 30 percent globally.
In a commentary also published in Nature, Konstantin Klemmer from Microsoft Research New England in Cambridge and Esther Rolf from Harvard University in Boston (both in the US state of Massachusetts) write that the new maps enable a more comprehensive inventory of human activity on the seas than ever.
