Investors can’t manage what they can’t measure and in the $40 billion global tuna industry, they’re largely flying blind. Despite accounting for nearly half of the world’s tuna catch, most of the sector’s biggest companies disclose almost nothing about what they harvest, where they operate, or how they fish. A new report from financial think tank Planet Tracker reveals just how much critical information is missing, and why that lack of transparency poses a growing risk to portfolios, markets, and marine ecosystems alike.
A Billion-Dollar Sector Without A Balance Sheet
Planet Tracker’s Tuna Turner: Investors Must Turn Up Transparency in the Tuna Industry, reveals that only four of the world’s 30 largest tuna fishing companies disclose their catch volumes, and only one, Bolton Group, goes further to reveal species-level, gear-specific, and location-based data. These 30 firms account for nearly half of the global tuna harvest.
“The tuna fishing business relies on one thing: fishing tuna,” says Francois Mosnier, head of Planet Tracker’s Ocean Programme in an interview. “By not disclosing how much tuna these companies catch and where they operate, they prevent investors from quantifying and understanding the main driver of their business success and main driver of associated risks.”
By comparison, other environmentally sensitive sectors like palm oil are more advanced in disclosure. Over half of companies in the palm oil sector now publicly report mapped plantation areas, basic disclosure investors use to evaluate deforestation risks. The tuna sector, by contrast, is still operating largely in the dark.
“Dark” Fishing And Legal Exposure
One of the most alarming findings in the report is that an estimated 56% of the tuna catch attributed to the largest companies is untraceable, a phenomenon known as “dark” fishing. That’s more than 1.3 million tonnes of fish whose origin, ownership, and method of capture are unknown.This means there is no public data linking the fish to specific companies or vessels, either due to undisclosed ownership or vessels operating with their satellite tracking systems (AIS) turned off.
According to Mosnier, this lack of transparency doesn’t just raise environmental red flags, it could trigger serious legal, market access, and reputational risks. “Not disclosing which vessels are owned or operated can raise suspicions that the company might be exposed to reputational, market access, and even legal risks,” he says. “In the EU, financially supporting companies found to be engaged in illegal, unreported or unregulated fishing is a serious infringement as per Article 90(2)(h) of the revised EU Fisheries Control Regulation.”
With vessels essentially disappearing from global tracking systems during fishing operations, investors are left to guess at whether their capital is tied to illicit, unsustainable, or even criminal activity.
The Ecological Cost Of Data Gaps
The FAO’s 2025 State of World Marine Fishery Resources report, released during the UN Ocean conference, underscores the sector’s fragile foundation, reporting that 35.5% of all global fish stocks are now overfished, up from just 10% in 1974.
While tuna remains among the most landed species and many stocks are currently considered “relatively healthy,” the report also notes continued negative trends in highly migratory species, and historical data shows declines of ~90% in key populations like Pacific and Atlantic bluefin tuna since the 1950s. This is especially urgent given climate drive changes to tuna migration patterns, reproduction and abundance.
“There has been a lot of improvement in the tuna sector in terms of reduced overexploitation, which needs to be celebrated,” Mosnier acknowledges. “However, several species remain threatened with extinction. The more a company relies on these species to derive revenue, the more their long-term revenues are at risk.”
Mosnier highlights companies such as Albacora, Maruha Nichiro, Dongwon, Bolton Group and Sajo as likely harvesters of these threatened species. He cites Nissui’s decision to disclose its catch of threatened species as a model for others to follow. While sharing catch data poses reputational risks, Mosnier argues it also signals leadership in a sector under growing scrutiny.
It’s worth noting that the issue goes beyond tuna. Industrial fishing methods more broadly are responsible for large-scale collateral damage. A 2024 Earth.org global synthesis estimated 38.5 million tonnes of bycatch are discarded each year, making up around 25% of total marine catch. Not only that but the IUCN estimates that 33% of sharks, rays, and marine mammals are now threatened with extinction, largely due to bycatch and overfishing.
This is especially troubling given the essential roles sharks, rays, and chimaeras play in ocean health and coastal livelihoods. Some species cycle nutrients across marine ecosystems; others help sustain carbon-sequestering habitats like mangroves and seagrass beds, contributing to climate resilience. They also underpin food security and income for vulnerable coastal communities. In fact, fisheries in some developing nations report that over 80% of their revenue depends on sharks and rays.
The Business Case For Disclosure
One of the big questions is why so few companies disclose their catch data or maintain active tracking. Concerns about piracy and competitive espionage are often cited. But Mosnier suggests that these fears are overblown, and that transparency actually offers a net financial benefit.
“Fears of being tracked by competitors or pirates are the main reasons we heard,” he says. “However, piracy risk is very localised, and even by modelling a negative impact of AIS-based spying by competitors on other vessels, we modelled a small positive impact of disclosure and AIS usage on a typical company’s financials.”
He adds that “ex post disclosure on catch volumes by area, species and fishing gear does not expose a company at all to increased competition or piracy risk, but makes it appear more transparent, and therefore more investable.”
Retail and Investor Pressure Mounts
A quiet but growing coalition of buyers and investors is now calling for greater traceability. Groups like the Global Tuna Alliance and the Seafood Investor Action Group are pressuring the tuna supply chain to clean up its act.
But meaningful progress depends on what Planet Tracker calls a “minimum disclosure standard”: catch volumes, species caught, fishing method used, and area of operation.
“The industry is fragmented and underprepared for regulation,” Mosnier says. “Companies must take voluntary action now, or face far more disruptive mandates later.”
The Missed Financial Upside Of Transparency
The financial upside isn’t just theoretical. “The financial benefits of transparency are mainly driven by an improved brand image that can result in preferred supplier status with some buyers, lower borrowing and/or insurance costs, and improved valuation multiples,” Mosnier explains.
Planet Tracker estimates that eliminating data gaps in ownership and AIS compliance could increase profits and valuations by 0.6% and 1%, respectively, within five years. Similar financial patterns have already been demonstrated in the palm oil industry, where greater transparency aligns with improved ESG scores and market access. Mosnier adds, “I can’t see why the same should not apply to tuna, but before that, companies need to disclose better catch data.”
The Risks Of Inaction
If companies and their backers fail to act, tuna assets could become stranded. Regulatory shocks have already affected profitability, as for example limits on fish aggregating devices (FADs), which disrupted harvests for some fleets. As global pressure mounts, poorly prepared firms will be the first to suffer.
“Recent announcements at the UN Ocean Conference have shown that regulators continue to respond to pressure,” says Mosnier. “An industry that is mostly not transparent on its catch and impact on marine ecosystems (some companies are) and relatively fragmented (30 companies control 46% of the volumes in our estimates) is not in a strong place to argue against increasing regulation requirements, even though they try.”
His message to investors is the importance of full disclosure as a minimum requirement: what’s caught, where, how, and how much.
While the tuna industry’s opaque practices may be an environmental threat, they are also a direct material risk to investment portfolios, global food systems, and regulatory compliance. Without transparency, investors can’t distinguish responsible actors from bad ones, and that’s a problem that can no longer be ignored.
