Guest Blog: Harvest Strategy for Yellowfin Tuna for the Western and Central Pacific? Projected benefits abound among possible future scenarios

August 23, 2023

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Nilmawati
Regional Sustainable Tuna Policy Coordinator, WWF Coral Triangle Program
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This week, as the 19th Scientific Committee (SC) of WCPFC convenes, a new study can help inform the ongoing evaluation of proposed management measures for skipjack, bigeye and yellowfin tuna in the Western and Central Pacific Ocean (WCPO).

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With the landmark adoption of a harvest strategy for skipjack last year, the Scientific Committee for the Western and Central Pacific Fisheries Commission (WCPFC) can continue the momentum to ensure sound harvest strategies are similarly applied for other key tuna stocks in the WCPO – notably for bigeye and yellowfin. 

Yellowfin tuna is a highly-valued economic commodity for many countries in the Pacific. In 2020, the Philippines exported a total of 186,166 metric tons of tuna product, of which yellowfin comprised 40%, while 48% of all tuna caught in Indonesia’s archipelagic waters were yellowfin. Meanwhile, yellowfin tuna became Vietnam’s most important wild-capture export product in 2022 (nearly 18,000 metric tons). 

As harvest strategies may call for catch reductions at times, it is important to acknowledge and understand the multi-sectoral implications of implementing such harvest strategies, especially for the livelihoods of millions of fisherfolk (over 90% of the fisherfolk in Indonesia and Philippines are considered small-scale) many of whom rely heavily on tuna fisheries, as well as Member States’ economies.  As a highly migratory species, the yellowfin tuna stock that spawns and feeds in the archipelagic waters of Indonesia and the Philippines travels a vast range that encompasses most of the Western and Central Pacific Ocean, adding additional complexity to their management.

With little known about the potential costs and benefits of implementing harvest strategies for the Southeast Asian countries, WWF worked with a team of modelling experts led by Dr Megan Bailey of Dalhousie University to model the impact of four potential approaches to fishery management that would help sustain and rebuild bigeye and yellowfin tuna stocks. The four candidate harvest strategies are:

1. restrictions on the use of fish aggregation devices (FAD) to reduce juvenile catch of yellowfin and bigeye
2. overall reduction in fishing effort of bigeye and yellowfin tuna to rebuild both stocks
3. limits to beach seining to ensure the sustainability of prey, and 
4. overall reduction in skipjack fishing effort by 10% by: (a) Indonesia only; (b) Indonesia and the Philippines; and (c) Indonesia, the Philippines and Vietnam.

By modelling the multi-species and multi-gear fisheries in WCPFC’s jurisdiction, the study seeks to help stakeholders understand the “true costs” and ensuing trade-offs intersecting socio-economic, biological and ecological impacts of a harvest strategy, as a first step to preparing for them. This can then lead to recommendations on how to address the potential trade-offs. 

In June this year, as part of Sustainable Tuna Partnership 2 project my colleagues and I convened with Ciara Willis, a representative of Dr. Bailey’s team, and other  fisheries scientists and officials from Indonesia, Philippines and Viet Nam to gather the information needed for this simulation study. Initial results from the simulation study have already produced projected potential benefits of implementing harvest strategies. It demonstrates that the overall sum of profits per country is greater under all harvest strategy scenarios than under current management, in addition to enabling sustainable catch and healthy yellowfin and bigeye spawning stock biomass in the future. With more accurate data inputs, the model could more accurately map out possible scenarios of what it would give (and take) to sustain the yellowfin tuna stock in the region. 

Considering the study’s result as well as the significance of yellowfin tuna for the economy and livelihoods of coastal communities in Indonesia, Philippines and Viet Nam, representatives from the three countries have agreed that there is an urgent need for regional harvest strategies specific to yellowfin tuna.

On 16 August, the 19th Scientific Committee of WCPFC began a week-long meeting to discuss proposed management measures for tropical tunas in the Western and Central Pacific Ocean. In ongoing discussions this week, Indonesia spoke to the shared interests of Viet Nam, Indonesia and the Philippines of ensuring sustainability of yellowfin tuna stocks in the region.

Through continued regional dialogue and greater scientific understanding provided by this “true costs” study, we look forward to the WCPFC acting upon its prior commitments in the earlier agreed work plans for adopting a harvest strategy that supports sustainable yellowfin tuna.