Joint Fish Stock Assessment In The South China Sea: Sustaining A Good Catch – Analysis

July 8, 2026 
By Lucio Blanco Pitlo III

Key Takeaways

Fish Stocks Ignore Borders — Highly migratory species like tunas, mackerels, and squids require regional cooperation. Joint stock assessments provide essential scientific data for sustainable management in the South China Sea.

Ongoing Practical Cooperation — The Common Fisheries Resource Analysis (CFRA) has completed two rounds of assessments (skipjack tuna and little tuna) with a third (squids) underway, involving scientists from China, Indonesia, Malaysia, Philippines, and Vietnam.

Low-Politics Success Model — CFRA avoids sensitive sovereignty issues, uses voluntary participation and shared methodologies, and demonstrates that science-based collaboration can build trust and prevent overfishing despite territorial disputes.

Analysis

Fish knows no boundaries. Straddling and highly migratory commercial species like tunas, billfishes, mackerels, and squids do not recognize artificial lines drawn on the sea. Hence, managing such transboundary stocks requires regional, if not international, cooperation. And one cannot manage something one cannot measure. This highlights the significance of conducting joint fish stock assessments to gauge the health, size, and factors affecting wild marine catch. Although less known, two rounds of joint fish stock assessments have already been conducted in the South China Sea (SCS), with the third underway. Hence, while the sea’s reputation as a flashpoint gets more limelight, coastal states continue to pursue practical cooperation, quietly but effectively.

Joint fish stock assessments help science, industry, and diplomacy. They provide a basis for data-driven solutions to manage commercial fisheries bounty that defies borders. They foster collaboration between marine scientists and policymakers of neighboring coastal states. This partnership can prevent a tragedy of the commons, in this case, the collapse of rich fishing grounds beyond the point of recovery. It creates a platform for non-sensitive, pragmatic, and science-based cooperation without prejudice to competing sovereign claims. Years of sustained work can gradually build trust and confidence. Along with economic impetus, it can help set the stage for bigger undertakings, such as fisheries arrangements or maritime boundary delimitation. Joint fisheries surveys are not unprecedented, with ample extant cases offering valuable references.

Precedents and success stories

The North Sea has one of the most institutionalized fisheries cooperation. Stock assessment is conducted by the International Council for the Exploration of the Sea (ICES), while management decisions are negotiated jointly by the European Union, the United Kingdom, and Norway. ICES, founded in 1902 by eight Northern European coastal countries, provides advice on sustainable catches. It now has 19 member countries, and its geographic coverage has expanded to other areas of the Northeast Atlantic. Economics is a key motivation. North Sea’s approximate annual fisheries landed value alone is $3-4billion, an industry too big to be lost to unchecked fishing.

Considered a gold standard in fisheries cooperation amid overlapping maritime claims is the one between Norway and Russia in the Barents Sea. Their Joint Fisheries Commission meets annually to determine total allowable catches (TAC) and allocate quotas for their fishermen and for those of third countries. Cooperation on fisheries research between the two sides has a long history dating back to the 1900s, becoming more organized in the 1950s and formalized through agreements reached in 1975 and 1976. The joint management prevents overfishing and ensures the sustainability of a billion-dollar annual catch of cod, haddock, and capelin. Last year alone, $2 billionworth of cod and other seafood landed in Norwegian ports. In 2010, the two countries agreed to demarcate their maritime boundaries. Even after this, the Joint Fisheries Commission continues to serve as a coordination framework for setting TACs and quotas for transboundary fisheries.

Taking cues and localizing

In contrast to long historical and formal fisheries cooperation in northern Europe, management of straddling and highly migratory fish stocks in East Asia’s waters remains fragmented. This is despite the region’s semi-enclosed seas, such as the SCS, being home to some of the most biodiverse and abundant commercial marine catches. The absence of bodies like ICES led to weaker scientific coordination, a higher risk of overfishing, greater exposure to illegal, unreported, and unregulated (IUU) fishing, uncertain long-term viability of the capture fisheries industry, and heightened political tensions. Some countries have entered into fisheries agreements, but these have yet to lead to regular joint scientific work and comprehensive stock surveys. For instance, China has entered into fisheries pacts with Japan (signed in 1997 and entered into force in 2000) in the East China Sea and with South Korea (signed in 2000 and took effect in 2001) in the Yellow Sea.

The fisheries accord between China and Vietnam in the Beibu Gulf, signed in 2000 and entering into force in 2004, is probably among the most advanced in the region. Unlike those reached by Beijing with Tokyo and Seoul, this deal came with a maritime boundary delimitation. The agreement established a joint fisheries committee and facilitated joint stock assessments. It capped the number of fishing vessels allowed to operate in the Common Fishery Zone and included a provision for setting allowable catch based on joint surveys.

In the Sulu-Sulawesi Seas, a subregional governance framework is evolving, promoting joint identification of transboundary fishery issues, collaborative scientific work, ecosystem-based fisheries management, data sharing, and harmonization measures. These developments, though relatively new, are promising and offer hope for future management of transboundary fisheries in choppy waters.

Defying the odds

Joint stock assessment in the SCS is done through the Common Fisheries Resource Analysis (CFRA), a groundbreaking initiative. Like the North Sea, SCS is a semi-enclosed sea bordered by multiple countries. But unlike the Mediterranean or Black Seas, there is no dedicated regional fisheries management organization (RFMO) for SCS. Coastal states surrounding the marginal sea neither have formal delimitation nor fisheries agreements, except in the Beibu Gulf between China and Vietnam. Hence, CFRA’s ability to thrive despite the lack of a sturdy anchor is commendable. As a pioneering undertaking in SCS, CFRA can lay the foundation for greater fisheries cooperation in the future. Hosting 12% of the world’s total catch estimated at $21.8 billion, the stakes are high in promoting sustainable fishing in SCS.

CFRA is a voluntary scientific partnership involving participants from China, Indonesia, Malaysia, Philippines, and Vietnam. More than 100 scientists and policymakers gathered for a series of workshops from 2018 to 2022 to develop shared evidence to inform cooperative management of the sea’s bounty. An informal SCS Fisheries Working Group was formed. A uniform methodology, the length-based spawning potential ratio (LBSPR), was adopted to assess the status of selected species.

The first CFRA result on skipjack tuna was published in a simultaneous event in Manila and Beijing in 2022. Former Philippine National Security Adviser Dr. Clarita Carlos delivered the keynote speech, where she stressed the importance of pursuing low-politics cooperation to build trust and confidence. The second round focused on the little tuna, and the findings were shared in a seminar in Qingdao in 2025. The third iteration is looking at the Mitre squid and the Indian Ocean squid. As squids are particularly sensitive to changes in water temperature, the third survey can also reveal the effects of global warming and climate change on SCS’s capture fisheries.

CFRA demonstrated the possibility and salience of continued cooperation among state-affiliated scientists and experts to provide a big-picture perspective on a specific fisheries resource that no single country can provide. Certain common standards, including a shared method for assessing a particular transboundary stock, were embraced. Its success can be attributed to several features. First, participation in the process was voluntary, and policymakers were involved. Second, territorial disputes and other sensitivities were avoided. Third, the sharing of raw data or other sensitive information was not required. In the early stages, fisheries managers, diplomats, and government officials convened to create a shared strategy. A reputable international non-government organization, the Swiss-based Centre for Humanitarian Dialogue, was a key player, serving as the secretariat and facilitator.

In sum, joint fish stock assessment in SCS is a good start worth sustaining. Collaboration among marine scientists can provide valuable advice in managing transboundary fisheries, averting a tragedy in the maritime commons. Joint capture fisheries surveys can recommend maximum catches, prohibit certain fishing practices, and suggest a common closed fishing season to allow stocks to replenish naturally. Coastal states can also cooperate to restock overfished areas. That such joint surveys are now in their third round shows that coastal states can rise above the noise and still carry on practical cooperation quietly but effectively.

As the history of the North and Barents Seas revealed, preserving the economic value from capture fisheries wealth can move states to cooperate even without delimitation or formal fisheries agreements. That said, it helps if such worthy scientific activities are spared from political or diplomatic turbulence.

About Lucio Blanco Pitlo III
Lucio Blanco Pitlo III is a Research Fellow at the Asia-Pacific Pathways to Progress Foundation. He was a lecturer at the Chinese Studies Program at the Ateneo de Manila University and the International Studies Department at the De La Salle University and contributing editor (Reviews) for the journal Asian Politics & Policy. He is also a member of the Board of Directors of the Philippine Association for Chinese Studies. He obtained his Master of Laws from Peking University and a MA International Affairs at American University in Washington D.C.
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