Use case explained: Illegal fishing monitoring


Thanks to everyone who participated in the first-ever SAR Use Case Tournament, an Ursa Space, March Madness-inspired event to spotlight the array of real world problems that can be solved using synthetic aperture radar (SAR).

The winner was… Illegal Fishing Monitoring. This use case dominated a tough field, beating out Sanctions Enforcement, Deforestation and Flood Mapping. Check out the bracket below.

2021 SAR Use Case Tournament Round 4 Winner-1

There will be another chance to let your voice be heard. We plan to organize a sequel tournament with a fresh selection. Stay tuned for more!

As promised, let’s take a closer look at the tournament winner, a use case with significant economic and ecological consequences.

What is Illegal Fishing Monitoring? 

The term illegal fishing is often used as shorthand for a broader category that also includes “unreported” and “unregulated” activity.

Examples include:

  • Fishing without a license
  • Catching above a quota
  • Using prohibited gear
  • Not reporting or under-reporting catch
  • Fishing in a restricted area
  • Catching a prohibited species

Illegal fishing undermines sustainable fisheries, causes marine habitat destruction, and hurts local economies that rely heavily on legal fishing as a source of jobs and revenue.

It’s estimated that Illegal fishing accounts for approximately 30% of all fishing activity worldwide, equal to roughly 26 million tons of fish caught per year, and costs the global economy more than $23 billion annually.

Why do people do it? 

A growing demand for seafood worldwide has created a fishing boom. With the exception of 2020 when COVID-19 caused a downturn, the number of fishing vessels has increased every year since 2012, according to Global Fishing Watch.


Unfortunately, not everyone chooses to play by the rules. There is the widespread perception that the “rewards” of selling ill-gotten fish outweigh the risks of getting caught.

The risks are seen as relatively low in the territorial waters where fishing laws are lax and/or lightly enforced. The international community continues to draw attention to the issue, urging stakeholders to adopt best practices, but these efforts require full cooperation by Coastal States and Flag States that register vessels.

Another component is demand. Efforts are underway by consuming nations to prevent illegally harvested fish from reaching stores.

The United States, which is the world’s largest single-country market for fish and fish products, has programs in place to combat illegal fishing, including one that requires importers to provide key data allowing the catch to be traced back to the point of harvest.

How can illegal fishing be monitored? 

Monitoring fishing activity, in general, is an enormous task for any country. States exercise sovereign rights and exclusive fishery management authority over their Exclusive Economic Zone, which can extend 200 nautical miles (370 kilometers) offshore.

One tool that helps is the electronic tracking devices onboard vessels that transmit information on the ship type, size, location, course and speed.

How does AIS work? 

The International Maritime Organization (IMO) requires vessels of 300 gross tonnage and above to be equipped with an automatic identification system (AIS).

The intended purpose of AIS is collision-avoidance, but the technology has had a major side effect. It is now possible to know the whereabouts of any vessel in the world, as long as its AIS signal is turned on. Popular websites have even sprung up allowing anyone to track ships using a map-based interface.

However, the view displayed on the computer screen doesn’t capture the real situation with 100% accuracy. Some vessels “disappear” if the ship captain turns off the AIS signal.

The reasons for doing so varies. Ship captains are known to turn off AIS signals when transiting waters where piracy occurs to become less visible.

In other cases, “dark ships” have been found to be doing something illegal or questionable, including acts of illegal fishing.


How can SAR help catch illegal fishing activity? 

Satellite imagery can help close the information gap that exists when relying solely on AIS signals, since dark ships don’t actually disappear from the water. But which type of satellite imagery?

One of the main reasons why illegal fishing monitoring is considered a SAR use case is that SAR technology works in any weather, 24/7.

That’s in stark contrast to optical imagery, which only works without cloud interference during daylight hours.

The limitations posed by clouds make it impossible to reliably monitor the earth using optical imagery alone. Some 67% of the world is typically covered by clouds, with only 10% of the area over the oceans completely free of clouds at any given time.

It’s not to say that people aren’t trying to use optical imagery to monitor dark ships. Its availability and ease of use makes optical imagery a tool that can be leveraged by journalists and others with an interest in the topic, who from time to time document an example of illicit activity.

However, this approach doesn’t work when a more reliable and comprehensive product is required.

Having to wait days, weeks or even months until the weather improves can be unacceptable. Nor is everyone content to receive an occasional anecdote. They want to monitor specific ships, perhaps dozens of them at a time, wherever they sail, or to keep tabs on specific bodies of water, knowing about every ship that comes and goes.

Ursa Space is building and delivering solutions that satisfy these difficult requirements, leveraging our extensive network of satellite providers and data fusion expertise.

What is data fusion? 

The most effective technique to monitor illegal fishing, and more broadly, dark ships, combines SAR with other data sources (e.g., AIS).

That’s why we work with Spire, which detects AIS signals from over 200,000 vessels to provide real-time vessel tracking.

Incorporating AIS data helps identify potentially illegal behavior. A ship turning off its AIS raises a red flag, especially when the ship’s location before and after rouses further suspicion.

Dark Vessels 2

In a report by Oceana, an international conversation group, the authors found examples of ships turning their AIS off before entering protected marine parks and restricted national waters, raising concerns about possible illegal fishing.

Adding these types of clues greatly improves the odds of catching the illicit acts. They can help  figure out where and when to focus SAR imagery collection.

We work with select clients to help them answer questions related to illegal fishing and dark vessels. If you’re interested, email us at We’d love to have a chat.




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