Forced labor risk hiding in plain sight
Forced labor in fishing does not always announce itself. It hides behind incomplete records, opaque vessel histories, and supply chain gaps that are easy to overlook when documentation appears to be in order on the surface. The challenge is that by the time tuna reaches a processor or a retail buyer, the conditions under which it was caught are often several steps removed and difficult to verify retroactively.
What makes this particularly difficult for buyers is that conventional due diligence relies heavily on paper-based certifications and supplier declarations. These documents may be accurate, or they may not be. Without independent, real-time verification tied to vessel-level data, it is hard to tell the difference. The five patterns below are some of the more common indicators that a vessel or sourcing relationship may carry elevated forced labor risk.
1: Vessels operating with no AIS or VMS signal
A fishing vessel that goes dark on satellite tracking systems is one of the clearest warning signs in the industry. AIS (Automatic Identification System) and VMS (Vessel Monitoring System) provide continuous position data that allows authorities, buyers, and traceability platforms to verify where a vessel has been, how long it stayed in a given area, and whether its reported catch locations match its actual movements.
When a vessel disables or spoofs its AIS or VMS signal, it removes itself from independent oversight. This makes it impossible to verify whether the vessel was fishing in authorized zones, whether catch volumes are consistent with reported positions, and whether crew were kept at sea against their will for extended periods. Vessels with frequent or unexplained signal gaps should prompt additional scrutiny before their catch enters your supply chain.
This is particularly relevant for longline vessels operating in remote ocean areas where physical monitoring is limited. Satellite tracking is often the only independent check available at the first mile.
2: Transshipment at sea with no observer coverage
At-sea transshipment, the practice of transferring catch from a fishing vessel to a refrigerated carrier vessel while still at sea, is a legitimate and widely used method in tuna fisheries. It is also one of the most significant transparency gaps in the global supply chain. When transshipment happens without an independent observer or electronic monitoring system on board, there is no reliable way to verify what was transferred, in what quantity, or under what conditions.
From a forced labor perspective, at-sea transshipment can extend the time crew spend at sea without access to port, shore leave, or any external contact. Vessels that regularly transship catch without observer coverage may also be transferring crew, which creates additional risk of labor exploitation that goes undetected.
Some regional fisheries management organizations (RFMOs) require observer coverage for transshipment events, but enforcement varies significantly by flag state and ocean region. Buyers sourcing from vessels that transship without documented observer or EM coverage are accepting a meaningful verification gap.
Book a demo3: Vessels flagged to known IUU or blacklisted registries
Flag state registration tells you which country has legal authority over a vessel and its operations. Some flag states maintain rigorous oversight of their fishing fleets. Others are known for minimal enforcement, weak labor protections, and a history of vessels appearing on IUU (illegal, unreported, and unregulated) fishing blacklists maintained by RFMOs and international bodies.
A vessel flagged to a state with a poor compliance record does not automatically mean forced labor is present. But it does mean that independent oversight of crew welfare, catch legality, and vessel operations may be limited or absent. When combined with other red flags, flag state history can be a useful filter for prioritizing which vessels warrant closer investigation.
Cross-referencing vessel identifiers against RFMO blacklists, the PSMA port state measures database, and IUU vessel lists maintained by bodies such as the FAO is a practical starting point. Automating these checks against live databases reduces the manual effort involved and makes it easier to catch newly listed vessels before their catch moves downstream.
4: Missing or unverifiable crew welfare certifications
Certifications such as the FISH Standard for Crew, Fair Trade USA, and SMETA (Sedex Members Ethical Trade Audit) provide structured frameworks for assessing labor conditions on fishing vessels. When a supplier cannot produce current, verifiable certification records for the vessels in their fleet, that absence itself is informative.
It is worth distinguishing between certifications that have not yet been pursued and certifications that have lapsed, been suspended, or cannot be independently verified. A vessel that has never been assessed carries different risk than one whose certification was revoked. Either way, the lack of auditable labor-rights documentation makes it difficult for buyers to demonstrate due diligence if sourcing decisions are later questioned by regulators or retail partners.
In jurisdictions such as the EU and the USA, regulatory frameworks increasingly expect importers to demonstrate active supply chain due diligence on labor conditions, not just rely on supplier declarations. Buyers who cannot point to verifiable crew welfare records could face compliance challenges as enforcement matures through 2026 and beyond.
5: Abnormally long fishing trips with no port calls
Fishing trip duration is a useful proxy indicator for crew welfare risk. Extended time at sea, particularly trips lasting many months without a port call, can indicate that crew are being held on board beyond the terms of their contracts, denied shore leave, or prevented from leaving the vessel voluntarily. This pattern is associated with some of the most serious documented cases of forced labor in distant-water fisheries.
What counts as abnormal depends on the fishing method and ocean region. Purse seine vessels operating in the Western and Central Pacific may have different typical trip durations compared to longline vessels in the Indian Ocean. Context matters. But trips that significantly exceed the norm for a given fishery, especially when combined with no documented port calls and no observer records, are worth flagging for further review.
Satellite AIS and VMS data, when analyzed over time, can reveal patterns that individual trip records may obscure. Vessels that consistently operate at the outer edge of typical trip durations, or that show irregular movement patterns near carrier vessels, may warrant closer scrutiny before their catch is accepted.
Turn red flags into verified sourcing decisions
Identifying red flags is a useful first step, but acting on them requires access to the right data at the right time. That means moving beyond supplier declarations and paper-based certification checks toward systems that can verify vessel behavior, labor compliance, and catch origin in real time, before product changes hands.
SmarTuna’s digital traceability platform captures first-mile vessel data via satellite VMS and AIS, integrates crew welfare certifications and social audit evidence directly into each batch’s traceability record, and automates checks against more than 15 regulatory and certification databases. Each Raw Material ID links origin, composition, and verification criteria, so buyers can access auditable proof of sourcing conditions rather than relying on documentation assembled after the fact.
Forced labor risk in tuna sourcing is real, but it is also detectable. The patterns described above give procurement teams and sustainability leads a practical framework for asking better questions of their supply chain partners and for knowing what verified answers should look like.
Frequently Asked Questions
How do I get started with assessing forced labor risk in my existing tuna supply chain?
Start by mapping your supply chain to the vessel level — identify which vessels are supplying your tuna, their flag states, and whether they have any active labor certifications such as FISH Standard for Crew or SMETA. From there, cross-reference vessel identifiers against publicly available IUU blacklists maintained by RFMOs and the FAO. This baseline audit will quickly surface which supplier relationships need closer scrutiny and where your documentation gaps are most significant.
What if my supplier provides certifications but I can't independently verify them?
Unverifiable certifications are themselves a red flag. Legitimate certifications such as FISH Standard for Crew and Fair Trade USA are issued by recognized bodies that maintain public or auditable records — if a supplier cannot provide a certificate number, issuing body, and current validity date, treat it as unconfirmed. Request documentation directly from the certifying body rather than relying solely on what the supplier provides, and consider whether the certification covers the specific vessels supplying your product or only part of the fleet.
Is at-sea transshipment always a risk, or are there conditions under which it's acceptable?
At-sea transshipment is not inherently problematic — it is a standard and practical logistics method in many tuna fisheries. The risk arises specifically when transshipment events occur without an independent observer or electronic monitoring (EM) system on board to verify what was transferred and under what conditions. Buyers can mitigate this risk by requiring documented observer coverage or EM records for all transshipment events in their supply chain, and by prioritizing suppliers whose carrier vessels operate under RFMOs that mandate such oversight.
How long is too long for a fishing trip? Is there a specific threshold I should use as a benchmark?
There is no single universal threshold because normal trip duration varies significantly by fishing method and ocean region — a longline vessel in the Indian Ocean operates very differently from a purse seiner in the Western and Central Pacific. A practical approach is to benchmark trip durations against published norms for the specific fishery and gear type, then flag any vessel that consistently exceeds that norm by a meaningful margin, particularly when combined with no documented port calls. Satellite AIS and VMS data analyzed over multiple trips will give you a much clearer picture than any single trip record.
What's the difference between AIS and VMS, and do I need to check both?
AIS (Automatic Identification System) is a transponder-based system primarily designed for collision avoidance that broadcasts vessel position publicly and can be monitored by anyone with access to satellite or terrestrial receivers. VMS (Vessel Monitoring System) is a fisheries-specific tracking system mandated by most flag states and RFMOs, whose data is typically reported to fisheries authorities rather than made publicly available. Ideally, you want evidence from both: AIS gives you an independently verifiable position history, while VMS records are the official compliance record submitted to regulators — significant discrepancies between the two are themselves a warning sign.
What are the most common mistakes procurement teams make when trying to address forced labor risk?
The most common mistake is treating supplier-provided documentation as sufficient due diligence without independent verification — a supplier declaration or a scanned certificate does not confirm the conditions under which fish was caught. A second frequent error is applying due diligence only at the processor or trader level rather than tracing risk back to the vessel, which is where labor conditions are actually determined. Finally, many teams conduct one-time audits rather than ongoing monitoring, which means newly listed IUU vessels or lapsed certifications can slip through between review cycles.
How are regulations around forced labor in seafood supply chains likely to change in the near future?
Regulatory pressure is increasing on multiple fronts. In the EU, the Corporate Sustainability Due Diligence Directive (CSDDD) and existing import control frameworks are pushing importers toward demonstrable, documented supply chain due diligence on human rights — not just self-declared compliance. In the US, the Uyghur Forced Labor Prevention Act has established a rebuttable presumption model that regulators are watching as a potential template for broader seafood enforcement. Buyers who build verifiable, vessel-level traceability systems now will be significantly better positioned as enforcement matures through 2026 and beyond, rather than scrambling to retrofit compliance after requirements tighten.