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  • Writer's pictureTravis Turgeon

Is IUU Fishing Really That Hard To Stop? How One Ship Evaded Capture for Over a Decade

"The STS-50 grew notorious for its part in poaching operations for the Antarctic and Patagonian Toothfish - both lucrative cod species from the Southern Ocean."

For those who keep a close eye on the state of modern-day commercial fishing, one organization is sure to ring a bell of familiarity - Sea Shepherd Global. The Sea Shepherd Conservation Society is an international organization whose mission is to protect and conserve the world’s oceans and marine wildlife, and a big part of this mission is to help regulate commercial shipping and minimize the threat of Illegal, Unreported, and Unregulated (IUU) fishing. The organization works to defend all types of marine habitats and wildlife, from large animals like whales and sharks to smaller animals that comprise the base of marine ecosystems.

According to data from Sea Shepherd Global, approximately 20% of the fish taken from the sea comes from IUU fishing operations, and without a strategic approach, these numbers could very well rise faster and faster, eventually reaching a “point of no return” in terms of remediation.

Sea Shepherd has numerous vessels that make up its fleet, which are tasked to governments and maritime authorities worldwide to enforce fishing laws and track down and capture illegal fishing vessels. One of these vessels is the Ocean Warrior - an $8-million custom vessel built in 2016 to help mitigate IUU fishing in the Southern Ocean.

The Ocean Warrior is a 54-meter-long vessel equipped with four engines, long-distance fuel tanks, a landing pad for helicopters, and a water cannon that can target ships with around 20,000 liters of water a minute. All in all, the vessel is well-equipped to handle most open-water IUU fishing enforcement tasks.

The Ocean Warrior was initially built to help pursue Japanese whaling vessels in the Southern Ocean, but in 2018, it was tasked with patrolling duties off the coast of Tanzania to help capture illegal fishing boats.

However, in the first days of its patrol, the crew aboard the Ocean Warrior received a call for help from the Tanzanian authorities. As it would turn out, a notorious and long-sought-after illegal fishing vessel - the STS-50 - had escaped from a port in Mozambique, where maritime authorities were meant to be guarding the ship.

This is where our story begins…

A Brief History of the STS-50 and Its Role in IUU Fishing

The STS-50 is a 450-ton longliner vessel originating from Japan. The ship has taken many names throughout its history, including the Andrey Dolgov, the Sea Breez, and the Ayda. During the 2000s and 2010s, the vessel was part of a global campaign for illegal fishing and was one of Interpol’s most wanted ships.

* For the sake of this article, we will refer to the ship at all points in time as the STS-50

The STS-50 grew notorious for its part in poaching operations for the Antarctic and Patagonian Toothfish - both lucrative cod species from the Southern Ocean. According to data and incidences from numerous maritime authorities, the STS-50 had been running illegally for around 10 years, taking as much as $50 million in unlawfully captured fish. And while Interpol had issued international warnings and requests for information about the ship’s activity, the vessel’s owner and crew had been evading capture by using a variety of evasion tactics, which included:

  • Flying flags of convenience

    • Registering the vessel to fly flags from nations with lax maritime laws

  • Obscuring ownership with shell companies

  • Falsifying documents

  • Spoofing and Dark Shipping

    • Displaying false location and identification data or turning off AIS monitoring systems to avoid capture

The captain of the STS-50 was also well-versed in evasion and escape. When the ship managed to leave the port in Mozambique in 2018, it was the third time the captain had evaded capture in the past decade.

We outline a brief timeline of operations for the STS-50 below.

IUU Fishing Timeline and Capture of the STS-50


Operating as an illegal fishing vessel and sailing under numerous names, the STS-50 (Andrey Dolgov at this time) was engaged in IUU fishing operations in the Pacific Ocean, Indian Ocean, and Southern Ocean. During this time, authorities approached the vessel numerous times, at which point the ship would make a beeline for international waters where maritime authorities had no jurisdiction. Once in international waters, the STS-50 would unload its unlawful catch, mainly in Asian countries, and skew its reports regarding the number and types of fish caught to avoid fishing laws and sanctions enforcement.

Between 2008 and 2015, the vessel regularly changed its registry to fly “flags of convenience” and was reconfigured to participate in the lucrative catch and trade of illegal Toothfish. During this time, the vessel was estimated to take around $6 million worth of Toothfish per journey.


The STS-50 (Andrey Dolgov) was caught unloading illegal Toothfish in China, but before any sort of investigation began, the ship fled from China and headed for the Indian Ocean. After its escape, the STS-50 was listed as “IUU” - an international label used to mark fishing vessels as likely involved in Illegal, Unreported, and Unregulated (IUU) fishing.

At some point in 2016, the STS-50 (Andrey Dolgov) attempted to dock in Mauritius but was denied entry due to its “IUU” status. After this event, the ship’s name was changed to Sea Breez 1.


The STS-50, now operating as the Sea Breez 1 and flying under the flag of Togo, bounced around from port to port, unloading its catch and forging documents to evade capture. Eventually, Togo removed the ship from its registry, and its name was changed to the Ayda. While operating as the Ayda, the vessel changed registry and flew the flags of up to eight countries to confuse authorities and evade capture.

In January 2018, Interpol issued a “Purple Notice” for the STS-50 (Ayda), indicating that the ship was wanted for its role in IUU fishing.


In February, authorities in Madagascar were alerted that the STS-50 (Ayda) was docked at a port nearby. At this time, the ship was docked under the vessel’s final name, the STS-50, using a falsified IMO number and possessing forged documents. While all this information was known then, the ship still managed to escape and avoid detainment.

After escaping Madagascar, authorities attempted to track the vessel using its Automatic Identification System (AIS). However, the ship was using an evasion tactic called “spoofing” - in which a vessel transmits a number of false data signals to hide its actual location. In some moments during the pursuit, the STS-50 was displaying data points in approximately 100 different areas - making it nearly impossible to pursue the vessel with confidence. The ship managed to, yet again, evade capture.

In March, the vessel was spotted in Maputo, Mozambique, while anchored in Maputo Bay. This time, authorities managed to capture the ship. Yet again, however, the crew aboard the STS-50 regained control of the ship and escaped Mozambique.

Flashback to the beginning of our story, and this is where the Ocean Warrior - the Sea Shepherd vessel sent to the African Coast to help manage fisheries in Tanzania - was called into action.

While the Ocean Warrior was well-equipped to pursue the STS-50, it ran out of fuel, approximately 1600 km into the pursuit in the Indian Ocean. The Ocean Warrior was called back to shore, and, again, the outlook was bleak for the capture of the notorious IUU fishing vessel.

After yet another escape, several countries and organizations prioritized capturing this long-sought-after IUU fishing vessel. Eventually, the ship appeared on AIS radar, and shortly after, Sea Shepherd’s Ocean Warrior and the Tanzanian Navy were again in pursuit.

For three weeks, the vessel fled across the Indian Ocean, eventually reaching the territorial waters of the Seychelles. Since the area was out of Tanzanian jurisdiction, the navy could not pursue it further.

However, the Ocean Warrior and vessels from the Tanzanian Navy collected AIS data on the ship’s speed and heading, and the data was passed to other groups - eventually reaching the hands of the Indonesian Navy (the expected location of the ship based on its AIS data).

The STS-50 eventually entered the Malacca Straits - an area that is considered one of the world’s busiest trade routes and is currently booming with ships from all parts of the world. Since the area is so congested with ships, the STS-50 was lost among the AIS signals.

Still, the AIS data collected by Sea Shepherd and the Tanzanian Navy played a valuable role and led the Indonesian Navy to a spot where they could intercept the ship. On April 6th, the STS-50 was captured by Indonesian authorities approximately 60km off the coast of Weh Island.

Upon capture, 20 crewmembers were found onboard, coming from three countries: Russia, Ukraine, and Indonesia. Upon investigation, many Indonesian crewmembers said they were unaware that the ship was wanted or operating illegally, pointing to a likely possibility that they were forced laborers - a common tactic used in illegal fishing operations to obtain cheap or free labor. Upon further investigation, authorities uncovered that the ship was tied to organized crime in Russia, which may signify why the ship has had sufficient resources to evade capture for so many years.

How Alternative Earth Observation Strategies Can Help Mitigate Similar Situations in the Future

For over a decade, the STS-50 was able to avoid capture using a variety of evasion tactics and strategies. We outlined these tactics above, but the primary evasion techniques involved AIS data.

AIS data, while useful for several applications, has significant downfalls in vessel monitoring and capture. Not only can a ship simply turn off its AIS systems and stop transmitting its location data (dark shipping), but these systems can also be manipulated so that a ship appears to be in locations it is not (spoofing).

However, AIS data is not the only method for monitoring, locating, or pursuing ships of interest. AIS data can be used alongside other technologies to make it a far more valuable tool for maritime monitoring.

Companies like Spire Global, ICEYE, and Planet Federal know the limitations of AIS data and offer alternative space-based monitoring services that can help bypass some of the biggest drawbacks of AIS monitoring.

One of these methods is using Radio Frequency (RF) data to locate a ship of interest, even when that ship is not transmitting data on AIS. RF data is a broad term that describes the energy emitted (radio waves) from large objects like ships, cars, and machinery. When used alongside AIS data for validation or invalidation purposes, it can provide deep insight into a ship's movements or whereabouts and help identify and capture vessels involved in IUU fishing.

Space-based data providers like Spire Global help users monitor large areas of the ocean using small satellites in orbit. The RF data collected can be geolocated and traced back to the source, and the data can be further filtered by using AIS data, satellite imagery, and other open-source information to confirm or validate a ship’s position.

RF data is far harder to manipulate, and RF data collection is not hindered by cloud cover, foul weather conditions, or night - all of which make it hard to track vessels solely using AIS.

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