Tuna & High Seas Fisheries
Tuna and other high seas fisheries are some of the most important but challenging fisheries to sustainably manage.
Where complexity meets opportunity
Tuna fisheries are among the most globally important — and among the hardest to improve. They operate across vast ocean regions, span complex international supply chains, and can involve environmental, governance, and social risks that cannot be solved by any one actor alone.
Our collaborative work over the past decade has supported sustainability improvements in over 30% of the East Asian tuna longline fleet. Whether it's helping those fleets achieve Marine Stewardship Council certification, addressing human rights and environmental needs through Fishery Improvement Projects, or advancing transparency through electronic monitoring initiatives, 600 longline vessels are now producing tuna more sustainably than when we set out.
These efforts sit within a broader picture of progress. According to the FAO’s 2025 Review of the State of World Marine Fishery Resources, 87% of assessed tuna stocks are considered biologically sustainable, and 99% of global tuna landings come from stocks at or above sustainable levels. In 2023 alone, about 5.2 million tons of tuna were caught globally with the Pacific accounting for the majority of production.
At the same time, many high seas fisheries, including tuna, still face real challenges — from limited visibility at sea, to uneven implementation of management measures, to ongoing risks for ecosystems and crew. Squid fishing (one of the two largest fished high seas fisheries by volume) effort has grown significantly in recent years, yet only a small share of these fisheries are currently considered sustainably managed. In regions without strong governance frameworks, progress depends on collaboration across fleets, markets, and supply chains.
Much of this activity is concentrated in East Asia, where distant-water fleets from countries like Taiwan, South Korea, Japan, and China play a central role in global seafood production. A small number of countries account for the majority of distant-water fishing effort, making the region a hot-spot for improving how high seas fisheries operate.
Ocean Outcomes partners with companies, governments, NGOs, and fishery stakeholders to turn complexity into progress. Our work focuses on high-risk, high-impact fisheries like tuna and squid where improvements can strengthen environmental performance, support worker well-being, and build more transparent and resilient seafood systems.
Shaping fisheries management together
Tuna fisheries are managed across multiple jurisdictions, with key decisions made through Regional Fisheries Management Organizations (RFMOs) — international bodies responsible for setting rules on catch limits, monitoring, and conservation across the high seas.
Ocean Outcomes works across this broader system — supporting fishery and supply chain improvements on the water while contributing to global conversations that shape how tuna fisheries are managed. We participate as observers to several RFMOs most relevant to our work, including the Western and Central Pacific Fisheries Commission (WCPFC) and the Inter-American Tropical Tuna Commission (IATTC).
As observers, our focus is on supporting practical, science-based approaches — from strengthening monitoring and transparency to advancing management objectives that can be implemented effectively across fleets and regions.
As a contributing member of the NGO Tuna Forum, O2 also collaborates with leading NGOs to advance science-based management, strengthen transparency, and promote responsible practices across tuna fisheries worldwide.
From risk to results
Our work focuses on practical tools that help partners make progress — on the water and across supply chains.
Driving Fishery Improvement
We work with partners to design and implement credible fishery improvement pathways that strengthen management, reduce environmental impacts, and support progress toward global recognized standards.
Case Study: Raising the Bar in Korean Tuna Fisheries
In South Korea, O2 partnered with leading tuna companies — including Sajo Industries — to strengthen longline fishery performance, supporting MSC certification for 28 vessels and demonstrating how structured improvement can deliver measurable results.
Scaling Transparency at Sea
We support the adoption and use of electronic monitoring (EM) to improve visibility, strengthen compliance, and build accountability in high seas fisheries.
Case Study: Scaling EM Across Tuna Fleets
Across East Asia, partners are deploying EM systems to close data gaps where observer coverage is limited — helping turn increased transparency into better decision-making and stronger oversight at sea.
Advancing Worker Protections
We integrate human rights due diligence and worker-centered approaches into tuna fishery improvement efforts, helping partners better understand risks and implement practical solutions that improve conditions for crew.
Case Study: Worker-Centered Solutions in Taiwan
In Taiwan’s distant-water fleet, O2 is working with industry partners to pilot crew training and explore how tools like EM and onboard connectivity can improve access to information, strengthen protections, and support better conditions at sea.
Beyond the Catch
Improving tuna and high seas fisheries is not just about fish stocks. It’s about how seafood systems function and whether they work for the people, communities, and ecosystems that depend on them.
Stronger management, better data, safer working conditions, and more transparent supply chains all reinforce one another. When they come together, they create fisheries that are more resilient, more accountable, and better equipped for the long term.
That’s where we focus — working with partners to make progress that is practical, credible, and built to last.
Tuna and High Seas Fisheries Fishery Improvement Projects:
- Chen Hung Seafood Frozen Produce Co Ltd. Pacific Ocean Longline Tuna FIP (Active)
- Fue Shin Fishery Pacific Ocean Longline Tuna FIP (Active)
- Fue Shin Fishery Indian Ocean Longline Tuna FIP (Active)
- Indian Ocean Albacore Tuna Longline FIP (No longer involved)
- Nachi Katsuura Albacore Longline FIP (Inactive)
- South Pacific Albacore and Western and Central Pacific Yellowfin Tuna Longline FIP (No longer involved)
- Taiwan Tuna Longline Association Pacific Ocean FIP (Active)
Stories from the Field: Tuna and High Seas Fisheries
- Ocean Outcomes and Seafood Legacy Form East Asian Partnership
- Insights from Our Work on the Water — 2025 Reflections and Looking Ahead to 2026
- Human Rights Day 2025 - Advancing Dignity and Decent Work in Global Fisheries
- Building Better Due Diligence in Tuna Fisheries - Lessons from Social Responsibility Work in South Korea
- Expanded Worker Training Now Reaching Dozens in Taiwan’s Distant Water Fisheries
- At Our Ocean Conference, Spotlight Shines on Northeast Asia’s Tuna Fleets
- Ocean Outcomes Collaborates on Groundbreaking Project to Enhance Social Responsibility at Sea
- Sajo Industries Awarded Marine Stewardship Council Certification for Longline Tuna
- Taiwan's Largest Fishing Vessel Member Association Launches First Fishery Improvement Project
- Building Regional Capacity for Electronic Monitoring Across Taiwan
- Supporting Social Responsibility in Korea's Seafood Industry
- Leading Taiwanese Tuna Industry Association Commits to Sustainability
- New Partnership to Improve Worker Conditions on Asian Longliners
- NFI Crab Council Partners with Ocean Outcomes on Sustainability Envoy Position
- Assessing and Addressing Social Risks in Fishery Improvement Projects
- Electronic Monitoring and the MSC Standard 3.0 in Korea’s Largest Tuna Fisheries
- Indian Ocean Longline Tuna Project Launches
- Developing Solutions to Illegal Seafood Imports in Northeast Asian Markets
- South Korea’s Largest Seafood Industry Players Come Together to Support Sustainable Tuna
- Leading Taiwanese Tuna Company Pursues Sustainability Status
- Ocean Outcomes Expanding Portfolio of Tuna Work Across Northeast Asia
- Now Addressing Social Needs in Fishery Improvement
- Training Tuna Vessel Owners on Best Practices in Fiji and Taiwan
- New Fishery Improvement Project Launched to Address Sustainability Gap in Indian Ocean Tuna Fisheries
- New Tuna FIP to Drive Improvements on Hundreds of Chinese and Chinese Taipei Longline Vessels
- Improvement Efforts Lead to More Sustainable Fishing Practices in Japanese Sea Perch and Tuna Fisheries
- Bumble Bee Foods and FCF Partner with Ocean Outcomes to Improve Longline Tuna Fisheries
- Experts Responsible for World’s Largest Tuna Fisheries Come Together to Work Towards More Sustainable Management
- Sixth Tuna Management Workshop Takes Best Practices to West Africa Through Two Days of Hands-on Trainings
- Japan Looks to Improve Key Tuna Fisheries as Part of Blossoming Sustainable Seafood Movement
- Fifth Tuna Management Workshop Advances Knowledge of Tuna Sustainability in the Pacific Ocean
- O2 Supports 2nd Indian Ocean Tuna Management Workshop in Sri Lanka
- Expanding Capacity and Expertise in Policy, IUU, and China
- Iki Island Fishermen Take Inspired Action To Preserve Precious Bluefin Tuna