The shipment the AP tracked from the port of Benjina carried fish from smaller trawlers; AP journalists talked to slaves on more than a dozen of them.
A crane hoisted the seafood onto a refrigerated cargo ship called the Silver Sea Line, with an immense hold as big as 50 semi-trucks. At this point, by United Nations and U.S. standards, every fish in that hold is considered associated with slavery.
The ship belongs to the Silver Sea Reefer Co., which is registered in Thailand and has at least nine refrigerated cargo boats. The company said it is not involved with the fishermen.
"We only carry the shipment and we are hired in general by clients," said owner Panya Luangsomboon. "We're separated from the fishing boats."
The AP followed the Silver Sea Line by satellite over 15 days to Samut Sakhon. When it arrived, workers on the dock packed the seafood over four nights onto more than 150 trucks, which then delivered their loads around the city.
One truck bore the name and bird logo of Kingfisher Holdings Ltd., which supplies frozen and canned seafood around the world. Another truck went to Mahachai Marine Foods Co., a cold storage business that also supplies to Kingfisher and other exporters, according to Kawin Ngernanek, whose family runs it.
"Yes, yes, yes, yes," said Kawin, who also serves as spokesman for the Thai Overseas Fisheries Association. "Kingfisher buys several types of products."
When asked about abusive labor practices, Kingfisher did not answer repeated requests for comment. Mahachai manager Narongdet Prasertsri responded, "I have no idea about it at all."
Every month, Kingfisher and its subsidiary KF Foods Ltd. sends about 100 metric tons of seafood from Thailand to America, according to U.S. Customs Bills of Lading. These shipments have gone to Santa Monica Seafood, Stavis Seafoods — located on Boston's historic Fish Pier — and other distributors.
Richard Stavis, whose grandfather started the dealership in 1929, shook his head when told about the slaves whose catch may end up at businesses he buys from. He said his company visits processors and fisheries, requires notarized certification of legal practices and uses third-party audits.
"The truth is, these are the kind of things that keep you up at night," he said. "That's the sort of thing I want to stop. ... There are companies like ours that care and are working as hard as they can."
Wholesalers like Stavis sell packages of fish, branded and unbranded, that can end up on supermarket shelves with a private label or house brand. Stavis' customers also include Sysco, the largest food distributor in the U.S.; there is no clear way to know which particular fish was sold to them.
Sysco declined an interview, but the company's code of conduct says it "will not knowingly work with any supplier that uses forced, bonded, indentured or slave labor."
Gavin Gibbons, a spokesman for National Fisheries Institute, which represents about 75 percent of the U.S. seafood industry, said the reports of abuse were "disturbing" and "disheartening." ''But these type of things flourish in the shadows," he said.
A similar pattern repeats itself with other shipments and other companies, as the supply chain splinters off in many directions in Samut Sakhon. It is in this Thai port that slave-caught seafood starts to lose its history.
The AP followed another truck to Niwat Co., which sells to Thai Union Manufacturing Co., according to part owner Prasert Luangsomboon. Weeks later, when confronted about forced labor in their supply chain, Niwat referred several requests for comment to Luangsomboon, who could not be reached for further comment.
Thai Union Manufacturing is a subsidiary of Thai Union Frozen Products PCL., the country's largest seafood corporation, with $3.5 billion in annual sales. This parent company, known simply as Thai Union, owns Chicken of the Sea and is buying Bumble Bee, although the AP did not observe any tuna fisheries. In September, it became the country's first business to be certified by Dow Jones for sustainable practices, after meeting environmental and social reviews.
Thai Union said it condemns human rights violations, but multiple stakeholders must be part of the solution. "We all have to admit that it is difficult to ensure the Thai seafood industry's supply chain is 100 percent clean," CEO Thiraphong Chansiri said in an emailed statement.
Thai Union ships thousands of cans of cat food to the U.S., including household brands like Fancy Feast, Meow Mix and Iams. These end up on shelves of major grocery chains, such as Kroger, Safeway and Albertsons, as well as pet stores; again, however, it's impossible to tell if a particular can of cat food might have slave-caught fish.
Thai Union says its direct clients include Wal-Mart, which declined an interview but said in an email statement: "We care about the men and women in our supply chain, and we are concerned about the ethical recruitment of workers."
Wal-Mart described its work with several non-profits to end forced labor in Thailand, including Project Issara, and referred the AP to Lisa Rende Taylor, its director. She noted that slave-caught seafood can slip into supply chains undetected at several points, such as when it is traded between boats or mingles with clean fish at processing plants. She also confirmed that seafood sold at the Talay Thai market — to where the AP followed several trucks — can enter international supply chains.
"Transactions throughout Thai seafood supply chains are often not well-documented, making it difficult to estimate exactly how much seafood available on supermarket shelves around the world is tainted by human trafficking and forced labor," she said.
Poj Aramwattananont, president of an industry group that represents Thai Union, Kingfisher and others, said Thais are not "jungle people" and know that human trafficking is wrong. However, he acknowledged that Thai companies cannot always track down the origins of their fish.
"We don't know where the fish come from when we buy from Indonesia," said Poj of the Thai Frozen Foods Association. "We have no record. We don't know if that fish is good or bad."