Look in most kitchens in the United States and you’ll find a can of tuna. It’s the country’s staple fish, one that’s been associated with many a scandal over the years. But the latest is perhaps the most harrowing: the tuna trade is sitting on a bubbling undercurrent of human trafficking and slavery, and the world’s biggest retailers are keeping this corrupt industry afloat.

After it transpired decades ago that tuna fishing was killing dolphins, campaigns by NGOs and consumers resulted in some major improvements. Tuna consumers now tend to be savvy about what's sustainable and what isn’t, looking for signs of how the tuna were caught, including dolphin-friendly labels (although there are now claims that even these can’t be trusted).

Tens of thousands of fishing vessels around the world catch more than 4 million metric tons of tuna every year. According to research by the Pew Charitable Trusts, the United States accounts for 24 percent of the world’s canned tuna and more than 8 percent of fresh tuna consumed. There are international guidelines regulating where, how and how much tuna can be caught, aiming to maintain healthy fisheries and protect the marine environment.

But when it comes to regulating labor, the picture isn’t so clear. Reports of hundreds of thousands of men being trafficked to Thailand from neighboring countries with the promise of well-paid jobs, only to find themselves held captive, starved and beaten, are casting a dark shadow on the industry.

So how can you be sure the tuna in your kitchen isn’t a product of modern slavery?

Thai trafficking

Thailand is the world’s third biggest seafood exporter, after China and Norway, with a fishing industry worth an estimated $7 billion. Despite its size, and its importance for the world’s seafood supply, the industry has been under fire for the last few years.

According to the Thai government, there are as many as 300,000 people working in the fishing industry, 90 percent of whom are migrants. As the Thai economy develops, Thai men are moving away from fishing and into jobs with better working conditions. This has left the country with a shortage of thousands of workers, which is being filled by human trafficking, with men from Bangladesh, Cambodia and Myanmar being lured onto boats with promises of prosperity.

The Thai government has made a number of changes to address the labor shortage, such as setting the minimum working age at 18 and establishing a minimum wage, and requiring employment contracts and holidays. The government also amended its Fishery Act in 2015, which hadn’t been touched for 68 years, so fishing boats must now be registered and inspected.

But these measures only work if they’re enforced, and the inadequate law enforcement, regulation, data and cooperation in the country mean the government’s actions might not make much difference. In 2014, Thailand was downgraded to Tier 3 on the U.S. Trafficking in Persons (TIP) list, where it remains. The U.S. Department of State’s Trafficking in Persons Report 2015 describes the sickening conditions:

Thai, Burmese, Cambodian, and Indonesian men are subjected to forced labor on Thai fishing boats; some men remain at sea for several years, are paid very little or irregularly, work as much as 18 to 20 hours per day for seven days a week, or are threatened and physically beaten.

Despite knowing about the conditions hundreds of thousands of people are subjected to on Thai fishing boats, the U.S. hasn’t taken decisive action or applied strict sanctions against Thailand. According to the Associated Press, this is “because it is a strategically critical Southeast Asian ally.”

The U.S. government is, however, taking steps to make sure America isn’t implicated in slavery at sea. In early February, the Senate voted in favor of closing a legal loophole that had allowed the import of goods known to be the result of slave labor.

The Tariff Act of 1930 bars goods made by “convict, forced or indentured labor.” However, its “consumptive demand” clause stated the U.S. can import goods produced by slave labor if it’s not possible to produce those goods within the country. Effectively, this meant it was okay to import goods — like tuna — with full knowledge of the slavery involved in their production.

Estimates by the International Labor Organization say almost 21 million people are subjected to forced labor globally, and the practice generates $150 billion profit annually. As a major consumer, the U.S. could make a significant dent in this by closing the Tariff Act loophole. John Hocevar, director of Greenpeace’s oceans campaign, told Motherboard:

The changes we’re making here definitely will make a difference around the world for some fisheries and for many of the people that work on these boats, because the US is a huge market for seafood… Today, you can walk into almost any supermarket in the country and buy seafood that was caught illegally and harvested or processed by slaves. So to get from that to a situation where you can actually be confident that the seafood you buy in the US is ethical and environmentally sustainable is going to take a lot of work.

Silencing the media

Government regulation is changing at the source too. In March 2015, the Thai government imposed harsher legal penalties on human traffickers, of up to life in prison and a maximum fine of 400,000 baht ($13,333). In 2015, the government looked into four cases of trafficking related to Ambon Island, investigating ship owners, captains and brokers, and identified 32 Thai fishermen forced to work on Thai boats in Indonesia. So far the result has been feeble: only four people have been arrested.

The impact the media is having on the situation is very different. Investigations conducted by the Guardian and the Associated Press have revealed the shocking stories of some of the men being lured into slavery. These have already gone some way to putting a stop to slavery at sea; the Associated Press is claiming more than 2,000 fishermen were freed in 2015 as a result of its ongoing investigation.

Perhaps this is part of the reason for the fear emerging around reporting on cases of trafficking. The Thai government appears to be sensitive to what it considers false allegations in the media. When asked in March 2015 how the government will deal with reporters who don’t follow the official line, Thailand’s Prime Minister Prayuth Chan-ocha said, “We’ll probably just execute them….You don’t have to support the government, but you should report the truth.”

In 2013, the Thai Navy filed a criminal defamation lawsuit against two journalists for a 41-word paragraph they wrote on the Navy’s alleged profiteering from the trafficking of Burmese Rohingya asylum seekers. The journalists were cleared in court in September 2015, having faced a potential seven-year prison sentence, but the long process has only served to warn others of the dangers of putting a spotlight on trafficking.

Cases like this are discouraging the media from covering human trafficking, including in the fishing industry, effectively keeping it under wraps. Human rights advocacy group PEN American Center commented to the Guardian that the “government of Thailand should refocus its energies on curbing collusion in human rights abuses by members of its own navy, rather than frivolous attempts to camouflage them by shackling the press.”

The country’s updated laws also aim to protect whistleblowers from unnecessary lawsuits and prosecution, but whether this is effective remains to be seen.

Consumer action

Consumers and NGOs are also stepping in, targeting some of the big players in the industry. When the New York Times told Lang Long’s story in July 2015, seafood giant Thai Union Group came under fire. Long, who lived in Cambodia, had accepted the offer of a construction job in Thailand. After crossing the border he was held captive at gunpoint for days, before being forced onto a fishing boat, where he was enslaved for three years. He discovered that much of the fish he caught was destined for the Songkla Canning Public Company, a subsidiary of Thai Union Group, for canning.

The backlash led Thai Union to make some changes, including bringing all processing in-house as of 2016, to make sure “all workers, whether migrant or Thai, are in safe, legal employment and are treated fairly and with dignity.” In a statement, president and CEO Thiraphong Chansiri commented: “This is a positive step towards our goal of ridding the Thai seafood sector of illegal labor practices … We hope this reminds all operators that they must remain focused on promoting good labor practices — the abuse of human rights must not be tolerated.”

Four days later, the company issued another statement announcing its subsidiary Okeanos was cutting ties with a supplier found to be dealing with a pre-processor that was in breach of Thai Union’s newly updated code of conduct. The owner of the pre-processor was arrested by the Royal Thai Police, and the industry regulator was notified.

But is this too little, too late? Greenpeace thinks so, and is taking on Thai Union Group with a campaign and petition for the company to clean up its tuna business. Thai Union produces 610,000 tons of tuna per year, a significant amount of which is sold to consumers in the U.S. Greenpeace is collecting signatures to send to the CEO, because, “Thai Union, the largest canned tuna company in the world, has been connected to shocking labor and human rights abuses and allow wasteful and destructive fishing practices that attract, capture and kill other marine life including turtles and sharks — while driving some species of tuna towards extinction.”

One of the country’s biggest tuna brands, Chicken of the Sea, is produced by Thai Union. The Greenpeace Tuna Shopping Guide, which ranks 14 well-known canned tuna brands in terms of how sustainable, ethical and fair they are, warns consumers that there are “No signs of ensuring fish for the future by this brand, best to avoid.” Although there’s a human rights policy in place, Greenpeace points out that there’s no proof the company’s suppliers adhere to it, and “provides little information about where and how the tuna was caught and refused to answer questions about its sourcing.”

In fact, there’s a petition for Chicken of the Sea to “clean up its act,” which you can sign on the Greenpeace website.

Others are getting involved too. A group of consumers filed a lawsuit against Nestle, alleging that Nestle violated three laws in California prohibiting false advertising and unfair competition, because Thai Union Frozen Foods “knowingly uses forced labor to harvest fish used in the cat food.” In December 2015, consumer action group D.C. Residents Against Slavery picketed outside Walmart, calling on the retail giant to stop stocking shrimp supplied by Thai Union Group. And Green America has called on Costco to stop fueling slavery in Thai fishing.

Thai Union is making all the right noises, outlining the actions the company is taking and the partnerships it’s forging, to combat corruption and forced labor in its supply chain. But while suppliers are exploiting and abusing forced workers to catch and process the fish, making the company a profit, the company needs to be held accountable.

There isn’t a logo that will show you whether your canned tuna was caught by someone of his own free will — yet. But asking the tough questions and putting pressure on companies like Thai Union Group will help push the tuna industry’s dark secret further into the light, and put an end to slavery at sea.