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Technological breakthroughs are changing how researchers observe the world’s fishing fleet

A bucket of fish at a market in Labuan Bajo, Indonesia. Image by Rhett A. Butler for Mongabay

A bucket of fish at a market in Labuan Bajo, Indonesia. Image by Rhett A. Butler for Mongabay

  • Three new scientific papers describe methodologies for working with automatic identification system, or AIS, signal data, and what the information reveals about global fishing activities.
  • Two of the studies analyze how AIS data can be used to observe transshipment, which is when a fishing vessel transfers catch onto another vessel instead of bringing it into port itself.
  • A third paper uses AIS data to shine new light on which countries dominate industrial fishing and in what areas they’re particularly active.

For decades, researchers studying the global fishing industry had to cope with minimal data about what goes on out at sea. The ocean’s surface is so vast that most of what vessels do, especially once they are in international waters, goes unrecorded. Or at least, it’s not recorded in a way that’s available to scientific and public scrutiny.

Technological breakthroughs in recent years are putting an end to that. Marine scientist Boris Worm from Dalhousie University in Canada, who looks back on 20 years of research in this field, calls the trend “one of the biggest revolutions in fisheries.”

What has changed is that more and more fishing vessels are equipped with a device that regularly sends out a so-called automatic identification system, or AIS, signal. The signal carries information about the vessel, like its name, country of origin, speed and position. More and more satellites in the sky, shot into orbit by companies like Spire and Planet Labs, exist to gather these messages. Today, the sector has reached a point where there is a pretty complete picture of where vessels are and where they’ve been, at any given time, encapsulated in billions of individual AIS signals. At the same time, advances in machine learning and artificial intelligence are making it possible to see patterns in this glut of data.

“I felt right away this was a game changer,” Worm said, recalling when a grad student in his lab proposed studying AIS signals. Worm and his team subsequently learned that other researchers were on the same track, and they began comparing notes.

Now, a wave of scientific papers is coming out that describe methodologies for how to work with AIS data, and what the information reveals about global fishing activities. One group in particular, a collaboration between environmental watchdog SkyTruth, Global Fishing Watch and Google, has been instrumental in laying the groundwork for AIS data analysis. The group has created algorithms that can be applied to large amounts of data to show the type of fishing activity, location or travel path of vessels, and made some of this data accessible in the form of an interactive map.

Hundreds of fishing vessels (blue lights) plying the waters between Taiwan (center foreground) and China are seen from a satellite orbiting the earth. Image courtesy of NASA Johnson/Flickr.

One of the group’s recent studies, published in Frontiers in Marine Science, looks at one phenomenon in particular: a practice called transshipment, when a fishing vessel transfers catch onto a transport vessel with coolers on board instead of bringing it into port itself. Transshipment generally isn’t illegal per se, but the practice makes it more difficult to bring oversight into global fishing supply chains and curb illegal fishing and illegal labor, especially if transshipment events are not declared. Fishing vessels that transship their catch can stay out at sea for a long time without ever returning to shore, potentially trapping workers on board for months. If a refrigerated vessel makes multiple stops, the catch gets mixed up and its origin is obfuscated.

Just based on AIS signals, the researchers could see where high volumes of transshipment occur, and the countries of origin of vessels that tend to be involved in the practice.

One area of interest lies in the southern Atlantic Ocean, within the South East Atlantic Fisheries Organisation convention area, says SkyTruth’s Nathan Miller, one of the researchers leading the study. The AIS signals show that transshipment events appear to be occurring in this region, though it is illegal under the convention.

Another cluster of transshipment activity Miller points out is in the northwest Indian Ocean, a region recently reported to host a growing, unregulated fleet of Chinese squid vessels.

Knowing the areas in which high volumes of transshipment occur can help authorities act, for example by checking up on vessels as they come to shore. But the unprecedented level of transparency around activities like transshipment becomes even more relevant if you “turn it around,” Miller says. Fishing companies that commit to clean practices can use the data to prove their track record, and those that continually have huge gaps in their records would need to justify this.

“We can map entire networks and communities of good actors and bad actors, that’s what we’re thinking about now,” Miller says.

The study at Worm’s lab, published in Science Advances at the end of last month, also used AIS data to look at transshipment. It complements the work of Miller’s team by adding more detail on the types of ships involved in this practice, which can help identify what types of fish they likely had on board.

The paper includes a detailed case study on tuna, tracing the voyage of albacore tuna “from the hook to a retailer’s shelf,” according to the authors.

“In this case, individual fish travel roughly 17,000 km [10,600 miles] after catch, over a time span of about half a year, changing boats, owners, and processing facilities several times,” the authors write.

The path of albacore tuna from fishing location to retail shelf is shown. Reefer and fishing vessel tracks are in purple and blue, respectively; the area of fishing and transshipment is denoted by a dashed black rectangle; and EEZ boundaries are in light gray. Top left: Fishing and transshipment off Mauritius, port call into Port Louis. Top right: Close-up of transshipment event (dashed red circle). Above: Tracks of three reefers and 13 fishing vessels from January 2017 to February 2018. (1-A) and (1-B) (dashed rectangles) denote fishing and transshipment areas; (2) ports (asterisks) where reefers landed whole fish and fish is cut; (3) transport to reprocessing and canning facilities; and (4) transport of final product to retail.

Worm and his team were able to compare and supplement their findings with data supplied by the industry. “Ideally, every step of this complex supply chain is documented and recorded electronically, at sea and in port,” Worm says.

He says he hopes this type of work will eventually lead to a reform in the fishing industry and help curb fraud, which is prevalent in seafood everywhere in the world. In Canada, where Worm is based, roughly 40 percent of fish is mislabeled, he says. “Tuna in sushi is often not tuna; it’s escolar, a bycatch species. And what’s labelled snapper can be tilapia, a farmed fish.”

But with AIS tracking, Worm says, the days of easy seafood fraud could be over. “[Fisheries] will be more like agriculture. When you buy coffee or tea you can trace it back to the plantation where it was grown. Eventually, every fish can be traced back to where it was caught,” he says.

A third paper, also released in Science Advances last week, adds another dimension to the work with AIS data.

It doesn’t specifically look at transshipment, but at which countries dominate industrial fishing and in what areas they’re particularly active.

For example, it found that vessels registered to relatively wealthy countries like China, Japan and Taiwan are responsible for the vast majority of the trackable industrial fishing on the high seas beyond the borders of any nation. But they also dominated industrial fishing within the domestic waters of less-wealthy countries, pointing to a lopsided exploitation of resources. Especially on high seas this is a concern, because high seas fishery resources do not belong to a single nation, but rather are viewed as an international resource that is to be shared.

Knowing more about global fishing patterns can help inform policymakers and consumers, Worm says. And research is just getting started in this field. “We are just publishing these methods now,” he says. “AIS tracking is going to increase and become more elaborate.”

Banner: A bucket of fish at a market in Labuan Bajo, Indonesia. Image by Rhett A. Butler for Mongabay.

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