Science publishes Tracking the Global Footprint of Fisheries

Data on fishing activity out at sea has traditionally been imprecise, difficult to access, and spread between many different regulating authorities. With the publication today of “Tracking the Global Footprint of Fisheries” in Science and the release of a public dataset of global fishing effort we hope to enable researchers and fisheries managers to fully take advantage of AIS tracking data for ocean conservation. (Read this excellent article on the work in The Washington Post.)

The data and analysis presented in this paper have been the result of a long-term collaboration between researchers at SkyTruth, Global Fishing Watch, Google, and universities in the United States and Canada. The research has been led by David Kroodsma, research program manager at Global Fishing Watch. Other authors from the GFW and SkyTruth teams are Paul Woods, CTO of GFW, Nate Miller, SkyTruth research analyst, Tim Hochberg, machine learning engineer at GFW, and myself, an analyst at SkyTruth. Along with other academic researchers we have worked to characterize the population of vessels broadcasting AIS and to assess the limitations in AIS coverage and reception.

Central to the work being presented is a description of the data pipeline and modeling used to process the vast quantity of AIS data broadcast by the over 70,000 vessels now tracked in Global Fishing Watch. Machine learning was used to classify the tracks of these vessels and infer both where they were fishing and what type of fishing gear they were likely using. Based on vessel movements, models could even predict vessel characteristics like length and engine power.

The temporal and spatial precision of this new global fishing effort dataset highlighted some surprising regional variations. Weekends are often taken off by fishermen in Europe and North America. This is not the case on the Chinese coast where fishing is only interrupted by the Chinese New Year and a summer fishing moratorium. This can seen by comparing Chinese and non-Chinese fishing vessels in this data visualization from Global Fishing Watch.

The most distinct spatial patterns of fishing effort can be seen to result from differences in regulation.  More subtle effects are seen from variables like sea surface temperature and net primary production. Below, you can see 2016 fishing effort off the coast of Patagonia, which shows both intense fishing activity by foreign vessels just outside the EEZ boundary and a checkerboard pattern within the EEZ due to Argentine regulation of the hake fishery.

The data appearing in the image above is part of the public dataset that is being released along with our paper. Researchers can select maps for different regions or fishing gear types and also download the raw data underlying the images. To learn more about the study and to access the data, click here.

This publication and data release is a milestone for our analysis of the global AIS dataset for fishing vessels but we still have a lot learn about the patterns of vessel movements we have characterized here. We hope our work can spur an increase in the use of AIS tracking data for fisheries research and regulation and we look forward to working with more partners to better understand this new data resource for marine conservation.


Watch CNBC’s Oceans of Crime, featuring Bjorn Bergman

In case you missed it, you can catch the CNBC documentary Oceans of Crime, about human trafficking and other illegal practices that go into providing the world’s seafood here. SkyTruth ocean analyst Bjorn Bergman is featured in the final 20 minutes of this riveting investigative piece. (If you are having trouble viewing the entire episode, there’s a shorter clip of Bjorn and SkyTruth here.)

Read more about Bjorn’s work that lead to this investigation in these blog posts:

Unusual Vessel Behavior in the MH370 Search Area

Update on Fishing Fleet at MH370 Search Site

[Updated] Fishing Fleet at MH370 Search Site May Have Moved North

The Search for Sanchi

On January 6th, a tanker named the Sanchi collided with a cargo ship called the CF Crystal in the East China Sea causing a fire which killed nearly all of the crew and eventually sank the Sanchi. While the CF Crystal (which survived the collision) was only carrying grain, the Sanchi was carrying natural-gas condensate. This ultra-light oil is highly flammable which no doubt contributed to the blaze that prevented any rescue of the crew. Though there was originally hope it would evaporate quickly, there have been reports of it approaching the Japanese coastline. More persistent heavy bunker oil from the ship’s fuel tanks might also be leaking, compounding the problem.

Usually, we use radar imagery collected by the European Space Agency’s Sentinel 1 satellite to track and monitor oil slicks, but, in this case, the area is not completely covered by Sentinel 1, and what imagery we have seen has been washed out by strong winds that make it difficult to see slicks. We’ve been relying on multispectral imagery from Sentinel 2, but heavy cloud cover in the area has made it difficult to locate the slick and monitor the cleanup and salvage operations.

These Sentinel 2 images do not show the slick as clearly as radar images would. Because we are working in the visible spectrum, we can only see a faint difference between the ocean and the lighter-than-usual slick. We’ve done our best to boost the contrast to highlight the slick, so the color of the water might seem a little brighter than usual.

Sentinel 2 image taken on January 18, showing vessels and slick around site of Sanchi wreck. We inferred the location of Sanchi based on the movements of response vessels, reconstructed from their AIS tracking broadcasts.

We can see two vessels which appear to be either spraying chemicals to disperse the slick or deploying oil-skimming gear, from booms extending from either side, as shown in this zoomed image:

Closeup view of the previous image, showing cleanup vessel in greater detail.

This Planet image, also taken on January 18, showing part of a larger area of slick east of the Sanchi.

Thanks to Planet and their fleet of Dove satellites, we can see that the slick extends further to the east. We are also able to see the vessels in more detail:

This collection of close-up shows views of oil spill response vessels in the area from the previous image.

We have been following the ships in the area via their Automatic Identification System (AIS) broadcasts, and have seen a variety of Chinese and Japanese vessels come and go, including the Koyo Maru and Koshiki, Japanese patrol boats; the Dong Lei 6, a cleanup tanker; the Shen Qian Hao, a Chinese diving vessel; the Hai Xun 01, a Chinese Patrol Boat; and the Dong Hai Jiu 101, a Chinese Search and Rescue boat.  Based on the movements of these vessels, we’ve inferred the location where the Sanchi likely sank and is the source of this ongoing spill.

We are doing our best to monitor this area as the clean-up continues.

Monitoring Update: Oil Rocks In The Caspian Sea

The Oil Rocks (Neft Daşları)  is a massive offshore oil complex in the Caspian Sea. The complex was constructed in the late 1940’s by the Soviet Union and has been producing oil consistently since 1951. The area around the Oil Rocks has experienced catastrophe in the past, when a fire at a nearby platform was responsible for the death of 32 workers and a particularly nasty oil spill in December 2015.

As part of SkyTruth’s Watchdog program, we keep an eye on locations such as this. Over the past 2 months, we estimate that over 380,000 gallons of oil have leaked into the Caspian Sea, based on our assumption that the slicks we are observing are 1 micron (1/1000th of a millimeter) thick.

Above: The European Space Agency’s Sentinel 1 radar satellite captured this image on December 9th revealing a 306 square kilometer oil slick surrounding the Oil Rocks complex.

Above: Sentinel 1 collected this image of the Oil Rocks with a much smaller oil slick (23 square kilometers) on December 21, 2017.

Wind speeds in the Caspian Sea were as strong as 35 knots toward the south on December 21st and may have dispersed an additional volume of oil on the water’s surface.

Above: Sentinel 1 imagery from January 7, 2018 reveals the Oil Rocks leaking oil. The slicks cover a total area of 34 square kilometers.

Wind speeds were very low (between 0-15 knots) on January 7th heading southward, allowing the oil to form slicks around the complex.

And on January 13th, they were between 20-30 knots also heading southward. Similar to the image from December 21st, the high wind speeds may have contributed to dispersing the oil.

Above: The most recent Sentinel 1 image collected on January 19, 2018 reveals a massive oil slick emanating from the Oil Rocks complex, covering an area of 1094 square kilometers and containing at least 288,940 gallons of oil.

For context, 50,000 gallons of oil leaked from the SOCAR#10 platform during a fatal fire in 2015 mentioned above. And this massive Azerbaijani complex has a consistent leaky history on satellite imagery. Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan, the five countries surrounding the Caspian, all have efforts to tap into the Sea’s 44 billion barrel reserve. But this most recent satellite image from January 19th suggests a troubling future for the environment of the Caspian Sea.