In 2015, more than 2,000 fishermen were rescued from slavery on an island in eastern Indonesia. 

For years, they'd been subjected to depraved working conditions. Many reported being whipped with stingray tails, beaten, and starved, all while being forced to contribute to a seafood supply chain that trickled down to massive brands including retailers, supermarket chains and makers of pet food. They weren't paid for their labor.

It wasn't until seven years ago, after an Associated Press investigation revealed the truth, that these formerly enslaved workers were released, miraculously reunited with their families and brought relief in the United States. 

It was a heart-wrenching story, but one that accounts for only a fraction of fishermen enduring labor abuse across the seas. 

In a paper published Tuesday in the journal Nature Communications, Stanford researchers quantify just how deeply rooted such abuse -- and other illegal practices, like fishing in zones meant to conserve nature -- is in the global marine sector. Their results are shocking. 

After studying 792 fishing ports, they found 57% to be linked with either labor abuse or illegal fishing, and often both. And after analyzing more than 8 million fishing trips between 2012 and 2019 that ended at these ports, they found 82% were also associated with work abuse and unlawful fishing. Isolating labor abuse, they found over 41% of the studied ports specifically associated with it. 

These conclusions are thanks to a machine learning model that combined a database that tracked fishing vessels globally with firsthand accounts of fishing crimes from research institutions, businesses, human rights organizations and governments. 

The need for numbers

"We wanted to take a more quantitative look to try and estimate risks of these two activities," said Elizabeth Selig, a researcher at Stanford's Center for Ocean Solutions and co-author of the study. 

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. But if governments are to intervene more effectively, the first step is identifying how far fishing exploitation reaches. The team's new study is a solid step in that direction.

"Governments need to focus on strengthening legal and regulatory frameworks that ensure abuse doesn't happen, and that adequate inspections of catches are happening in ports," Selig said. 

Though most governments do have some standards in place to block abuse and illegal fishing practices, there are still gaps. For instance, Selig points out an unfortunate consequence of airtight security measures at ports. 

There are a lot of restrictions on "disembarkation," which simply means getting off the boat. Often, fishers are asked to show their passport to disembark. But what if they don't have access to that passport? Or what if they hold a visa that doesn't allow them to leave the vessel? 

"Imagine you don't speak the language, you may not have a cell phone that works in that country, you may not know how to access your embassy," Selig said. It'd be really hard, if not impossible, to report illegal activity and abuse happening on your vessel. That's why frontline human rights organizations, or easier access to port-based social services, are incredibly important to maintain, she stresses.

But the onus doesn't lie only with governments. 

"Companies need to improve traceability in their supply chains and co-design solutions with workers to prevent abuses," Selig said. 

That responsibility is well illustrated by a 2015 incident. As an attempt to self-police, giant food corporation Nestle found evidence of modern slavery in its seafood supply chain, a horrifying discovery that was eventually traced back to a multibillion dollar seafood vendor in Thailand. The company later warned that all US and European companies that purchase seafood from the same region are exposed to the same risk of labor abuse along their line of imports.

Defining the terms

An important aspect of Selig's research is the way her team decided to define "labor abuse."

"We took a little bit of a broader definition," Selig said. "In part, because we think that even though there's a lot of attention on the severe end of the spectrum, what's perceived as less severe abuses are often potential indicators of more severe abuses in the future."

Forced labor, for instance, like the eastern Indonesian operation, was on the more extreme end. Poor working standards, like uncleanliness or neglected worker rights, were on the less extreme end. 

But in terms of illegal fishing practices, the team followed a more standard definition. 

To be considered wrongful fishing, vessels had to be in contravention of either a country's general laws, conservation measures put forth by a regional fisheries management organization, a participant in unreported or misreported fishing, or even have fished in places with no applicable conservation measures.

Once the definitions were settled, the team began looking for correlations between labor abuse or illegal fishing reports and ports or vessels in the tracking database. They looked at full fleets to mitigate the chances of missing something. If one vessel showed signs of risky activity, another in the same fleet might too.

Flags and gear are clues

The team found that vessel flags, which show the country a vehicle is registered to, had a strong role to play when judging risks of labor abuse. 

"The riskiest flags were associated with [vessels] where the flag state ... is registered to countries that have what is considered to be poor control of corruption," Selig said.

When looking for risks of illegal fishing activity, Selig said, fishing equipment was telling. 

Riskier vessels tended to have gear focused on what's called trans-shipment, which is what happens when fishing vessels move their catches onto bigger vessels and those larger vessels take the catch to shore. 

Presumably, the team suggests, moving catches onto a bigger ship means there's less monitoring on the illicit ship, especially because trans-shipment happens in the middle of the ocean, not near ports. If something suspicious is going on behind the scenes in someone's boat, they'd probably want to reduce the amount of time they spend in ports with security guards. 

Going forward a major question is, How can we address these ongoing tragedies in the fishing industry?

"A big part of trying to unravel this puzzle," Selig said, is improving transparency and accountability in the recruitment process of fishers. "For them to understand their rights, their contract terms and to be able to seek recourse when there are violations."

This new paper, she adds, is one way "to help get us there."