Thailand is doing little to prevent the human trafficking of workers coming from other countries, and many of these indentured servants are finding their way to the fishing industry, where they are forced to work on vessels engaged in illegal, or pirate, fishing, a new report says.

The trafficked workers are subject to long hours, little or no pay and physical and mental abuse up to and including murder, with 59% of Thai fishing workers who were surveyed by the United Nations in 2009 saying they had seen a fellow worker murdered, according to the Environmental Justice Foundation report, “Sold to the Sea–Human Trafficking in Thailand’s Fishing Industry, released Wednesday.

Because of Thailand’s tight labor market, many people coming to the country for work wind up in fisheries, where they are subject to horrific working conditions, the report said. Many of these workers end up on illegal fishing vessels, and a recent report from the environmental group Oceana found up to 20% of the world’s fish are caught illegally.

“The men were subject to bonded labor, forced detention, physical abuse and threats of violence on the boats and in port. All had been at sea for at least five months and spoke of beatings by senior crew, the report said, citing interviews the organization conducted in March with six of 14 men from Myanmar who were rescued from a vessel while it lay in the port town of Kantang.

“Two of the interviewees reported seeing a fellow crewmember tortured and executed for trying to escape as well as witnessing the murder of at least five other individuals. Another former boat worker interviewed on a separate occasion in March 2013 witnessed multiple murders and the victims’ bodies being thrown into the sea.

The Thai embassy in Washington, D.C., did not immediately return a call seeking comment.

For the last three years, Thailand has been on the U.S. State Department’s Tier 2 Watchlist for human trafficking. The State Department report has in the past highlighted use of underage and exploited workers in Thailand’s seafood processing sector. A downgrade to Tier 3 status could impact Thai exports to the United States, and Thailand is the largest supplier of shrimp to the U.S.

In March, Thailand’s minister of foreign affairs issued a progress report citing his country’s efforts to combat human trafficking. The minister, Surapong Tovichakchaikul, visited with U.S. Secretary of State John Kerry earlier this month and asked him not to downgrade the country in the next Trafficking in Persons report, due out in June. Environmental Justice Foundation says its own report “raises serious questions about Thailand’s progress in combating and preventing human trafficking. It says the country should remain on the Tier 2 Watchlist until it submits a detailed action plan to tackle the problem–or be placed on Tier 3 status if it doesn’t make improvements.

“EJF has uncovered a huge number of pirate fishing operators and criminal businesses actively using forced and trafficked workers on their boats as a way to maximize their profits, Steve Trent, executive director of EJF, said in a statement. “The victims of this, often among the most vulnerable and desperate, are subject to horrific abuse, denied basic freedoms, forced to work punishing hours, savagely beaten and even murdered. There are no excuses for this modern day slavery and governments and business must come together to stamp it out.

Recommendations in the report include the banning of transshipments at sea, which the foundation says allows vessels–and their crews–to stay at sea for months or years at a time; ratify and implement the 2007 ILO Work in Fishing Convention to ensure international standards for decent work and living conditions on fishing vessels; and better protecting and making it easier for human trafficking victims to prosecute claims.

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