Scientists, AI, and Satellites in the Fight Against Illegal Fishing

Agreements designed to curb illegal fishing are still as full of holes as the meshes in fishing nets, a new study published by Stanford University’s Center for Ocean Solutions and Oceana analysts reveals.

Illegal, unreported, and unregulated (IUU) fishing generates annual economic losses of up to $25 billion, leads to significant damage to aquatic life, and is linked to human rights violations, warn scientists publishing their findings in Science Adviser.

Almost everyone poaches. Satellite surveillance of fishing vessels is a deterrent to poachers. Stanford University researchers claim that “vessel tracking using the Automatic Identification System (AIS) is a powerful tool in the fight against IUU.” However, they are aware that in many cases, AIS transponders are disabled. This reduces the effectiveness of this tool as an effective surveillance tool.

Scientists’ research and analysis of data on AIS deactivation in commercial fishing indicate that fishing vessels fish illegally for many millions of hours each year with their identification systems disabled. Exclusions most often occurred near the exclusive economic zones (EEZs) of Argentina and West African countries, and in the northwest Pacific Ocean. These are the areas most frequently targeted by fishing poachers.

Chinese Dominant Global Fishing

“New analysis by Oceana revealed the global scale of illegal fishing by Chinese fishing fleet vessels in June of this year,” reports Megan Jordan of Oceana. Oceana has published an analysis of China’s global fishing activity from 2022 to 2024. The analysis shows that “57,000 Chinese industrial fishing vessels dominated 44% of visible fishing activity globally during this period.”

Here are some key findings from Oceana’s research on Chinese fishing activity over the three-year period from January 1, 2022, to December 31, 2024: Fifty-seven thousand fishing vessels, primarily trawlers, flying the Chinese flag, fished for over 110 million hours. Chinese fishing vessels accounted for 44% of global fishing activity during this period.

Chinese vessels accounted for 30% of all high-seas fishing activity, fishing for over 8.3 million hours. They were most active offshore in South Korea (11.8 million hours), Taiwan (4.4 million hours), Japan (1.5 million hours), Kiribati (nearly 425,000 hours), and Papua New Guinea (over 415,000 hours). China fished in the waters of more than 90 countries for over 22 million hours.

Source: Science Advances

Illegal Fishing Plagues

The analysis used data from Global Fishing Watch (GFW). It cautions that the analysis only partially reflects Chinese fishing activity during this period, as it only includes vessels flying the Chinese flag and transmitting Automatic Identification System (AIS) data, making them visible to public tracking systems.

Dr. Max Valentine, Director of Illegal Fishing and Transparency Campaigns and Senior Scientist at Oceana, commented on the research findings:

“To protect our oceans and fisheries, we must know who is fishing where. It is crucial that we monitor the seas, paying close attention to the world’s largest fishing fleets, especially the Chinese fleet, which have been linked to illegal, unreported, and unregulated fishing and human rights abuses at sea.”

Illegal, unreported, and unregulated (IUU) fishing is a low-risk, high-return activity, particularly on the high seas, where fragmented legal frameworks and a lack of effective enforcement allow it to thrive. Oceana analysts note that “IUU fishing can include fishing without a permit, exceeding catch limits, operating in closed or protected areas, hunting protected wildlife, and fishing with prohibited gear.”

The impacts of illegal fishing are devastating for the marine environment. It emphasizes that “these illegal activities can destroy important ocean habitats, severely deplete fish populations, and threaten global food security. These activities not only contribute to overfishing but also give illegal fishermen an unfair advantage over those who play by the rules.”

Fishermen vs. Ecosystems

“The massive scale of China’s high-seas fleet has a profound impact on marine ecosystems worldwide. Transparency at sea is essential not only to track high-seas fleets but also to hold violators accountable, protect vulnerable communities, and ensure the sustainability of our oceans for future generations,” notes Dr. Marla (Max) Valentine.

Stanford University’s Center for Ocean Solutions revealed that “AIS shutdowns are most common near transhipment points and EEZ boundaries, particularly in disputed waters.” Links have also been noted between AIS shutdowns and concealing vessel locations from competitors and pirates.

Poaching also occurs in waters within the EU and neighboring jurisdictions. Over two years ago, on September 20, 2023, the European Parliament’s Fisheries Committee published a report showing that Chinese fishermen are leading poaching on a near-global scale. MEP Pierre Karleskind titled the report simply: “The Chinese fishing industry: a global threat to fish stocks that must be countered.”

  SOurce: EU Commision

A Fleet with Minimal Transparency

A report by Stanford University researchers states that “China’s distant-water fleet—the world’s largest—operates with minimal transparency, benefiting from massive government subsidies and often in unstable or poorly regulated maritime zones, particularly off the coasts of West Africa, the Pacific Islands, and Latin America.” The real threat of overfishing due to illegal fishing was recently reiterated by Olivier d’Auzon, Advisor on Maritime Security and Shipping and a legal expert on transport at the European Union and the World Bank.

Olivier d’Auzon states categorically:

“While European, African, and Latin American fleets adhere to sustainable development principles (quotas, inspections, traceability), China’s distant-water fleets often operate unchecked, without independent monitoring or reliable catch reporting—and sometimes under operating conditions that violate international standards.”

Illegal fishing has negative economic and ecological consequences. First, poaching creates unfair competition in fishing. From an ecological perspective, IUU fishing destroys fish stocks and hinders population recovery. D’Auzon notes that “from a logistical perspective, it introduces a hidden loop into the seafood supply chain.”

Inconsistent Standards

A study published in Science Advances warns that inconsistent standards applied to foreign and domestic fleets potentially undermine the treaty’s effectiveness. Adopted in 2016, the Port State Measures Agreement (PSMA) requires signatories to designate specific ports for foreign vessels, conduct standard inspections, and deny entry to vessels carrying illegal catches. To date, 83 countries and the European Union have signed up.

Using satellite data from Global Fishing Watch, the researchers estimated that landings at PSMA ports doubled between 2016 and 2021. They also found that vessels now have to travel almost twice as far to reach a non-PSMA port, raising costs for those trying to avoid inspection.

“One of the most promising tools we have is the Port State Measures Agreement (PSMA), the first global agreement aimed solely at combating illegal, unreported, and unregulated fishing,” said Elizabeth Selig, lead author of the study and managing director of Stanford University’s Center for Ocean Solutions.

Fishermen Under the Eyes of Port Inspectors

Selig explained the research: “We wanted to examine how vessels fishing in international waters have behaved since the treaty entered into force to understand what parties to the agreement could do to strengthen its implementation.”

“All fish caught by industrial fishing vessels must pass through port at some point to be landed and incorporated into the seafood supply chain after being caught, reaching market countries,” Jaeyoon Park, Senior Data Analyst for Research and Innovation at Global Fishing Watch and co-author of the study, explained the nature of the inspections.

In his opinion, “ports are often the last checkpoint where fish can be clearly linked to the vessel that caught it, and therefore offer one of the best and most cost-effective opportunities to identify, sanction, and prevent illegal fishing.”

Olivier d’Auzon believes that “the problem is not limited to uninspected fleets.” The goal is to shape a new era of global ocean governance, in which marine biodiversity, food security, and fair trade are intertwined, both at sea and on land. He believes that the future of the deep-sea fishing industry depends on transparency, compliance, and cooperation.

Therefore, full implementation of the 2022 WTO agreement on harmful fisheries subsidies is essential. Tighter requirements for source control of seafood imports are also essential. The inclusion of restrictive social and environmental clauses in trade agreements is also advocated. Closer cooperation with coastal states and regional fisheries management organizations is also essential.