More than 2,000 fishermen were rescued from slavery on an island off the coast of eastern Indonesia in 2015.

They'd been subjected to deplorable working conditions for decades. Many described being whipped with stingray tails, beaten, and starved, all while being forced to lead a seafood supply chain. These forms of maltreatment trickled down to major manufacturers such as vendors, grocery store chains, and even pet food producers.

These once enslaved workers were eventually released, miraculously reunited with their families, and brought relief to the U.S. only seven years ago, after an Associated Press investigation revealed the reality.

Stanford researchers assess how deeply established these abuses are in the worldwide marine industry.

The researchers analyzed 8 million trips that ended at these ports between 2012 and 2019. They discovered that 57% were involved in either labor abuse or illegal fishing. 41% of the analyzed ports were specifically linked to it. When it came to labor abuse, they discovered that 41% of the analyzed ports were specifically linked to it.

"Governments need to strengthen legal and regulatory frameworks that ensure abuse doesn't happen," Elizabeth Selig said. "Often, fishers are asked to show their passport to disembark, but what if they don't have access to that passport? It'd be really hard, if not impossible, to report illegal activity and abuse happening on your vessel.

"Right now concrete statistics on both labor abuse and illegal fishing are poorly known, mainly because the illicit nature of these practices means there's a strong incentive to "hide the numbers," she said.

The team located that vessel flags, which exhibit the country auto is registered to, had a potent position to play when judging risks of labor abuse.

Riskier vessels tended to have gear focused on what is known as trans-shipment, which occurs when fishing vessels move their catches onto larger vessels and those larger vessels choose the catch to shore.

A major concern for the future is, "How can we address these ongoing tragedies in the fishing field?"

"Improving transparency and accountability in the fisher recruitment system is a big part of trying to solve this puzzle," Selig said. "For them to understand their rights, the terms of their agreements, and to be prepared to seek redress when there are violations."

She described the new paper as a single way "to enable us to get there."

The findings have been published Tuesday in the journal Nature Communications.