Tracking the global footprint of fisheries

About

Agriculture, forestry, and fishing are three of the main activities by which humans impact the environment. Advances in satellite-based observation have allowed high-resolution monitoring of forestry and agriculture, creating opportunities such as carbon management, agricultural forecasting, and biodiversity monitoring on a global scale. In contrast, we lack a precise understanding of the spatial and temporal footprint of fishing, limiting our ability to quantify the response of global fleets to changes in climate, policy, economics, and other drivers. Although fishing activities have been monitored for selected fleets using electronic vessel monitoring systems, logbooks, or onboard observers, these efforts have produced geographically limited and incohesive data. As a result, the global footprint of fishing activity, or “effort,” could be inferred only from disaggregated catch data.

Recent expansion of the automatic identification system (AIS) vessel tracking technology presents an opportunity to fill this gap and quantify the behavior of global fleets down to individual vessels. Although AIS was originally designed to help prevent ship collisions by broadcasting to nearby vessels a ship’s identity, position, speed, and turning angle every few seconds, these messages are also recorded by satellite- or land-based receivers. In our inaugural partnership with Global Fishing Watch, we used AIS data to directly map global fishing activity.

Approach

We processed 22 billion automatic identification system (AIS) messages and tracked more than 70,000 industrial fishing vessels from 2012 to 2016, creating a dynamic, global footprint of fishing effort with a spatial and temporal resolution two to three orders of magnitude higher than that of previously existing datasets.

Key findings

Our data show that industrial fishing occurs in more than 55% of ocean area and has a spatial extent more than four times that of agriculture. We find that global patterns of fishing have surprisingly low sensitivity to short-term economic and environmental variation, and a strong response to cultural and political events such as holidays and closures. Over the course of 1 year (2016), our data set captured 40 million hours of fishing activity by vessels that consumed 19 billion kWh of energy and covered a combined distance of more than 460 million km, equivalent to traveling to the Moon and back 600 times.

The spatial footprint of fishing, as determined with AIS, is unevenly distributed across the globe. Global hot spots of fishing effort were seen in the northeast Atlantic (Europe) and northwest Pacific (China, Japan, and Russia) and in upwelling regions off South America and West Africa. Areas with minimal fishing effort included the Southern Ocean, parts of the northeast Pacific and central Atlantic, and the exclusive economic zones (EEZs) of many island states, forming conspicuous “holes” in the global effort map.

Partners

This project was a collaboration with Global Fishing Watch, made possible by funding from the National Geographic Society.