Enslaved on a Thai fishing vessel for 11 years, Tun Lin saw his fellow workers lose their minds one after another, with one fisherman jumping into the sea to end his life.

Some would start murmuring or laughing to themselves as they worked day and night in Indonesian waters on the cramped boat, often surviving on fish they caught and drinking water leaking from an onboard freezer.

“It was like a floating prison — actually, worse than prison,” the fisherman, who was sold into slavery from Myanmar, said in Samut Sakhon, a Thai fishing hub 40 km (25 miles) southwest of the capital, Bangkok.

The 36-year-old, who was rescued in 2015 after losing four fingers and being stranded on a remote island for years without pay, is now lobbying for fishermen’s rights with the Thai and Migrant Fishers Union Group (TMFG).

Under growing consumer pressure, Thailand has introduced a raft of modern technologies since 2015 — from satellites to optical scanning and electronic payment services — to crack down on abuses in its multibillion-dollar fishing industry.

It is one of a growing number of countries using innovation to deal with modern slavery, from mobile apps in India to blockchain in Moldova. But experts warn against over-reliance on tech as a silver bullet without stronger workers’ rights.

“Technology can be a double-edged sword,” said Patima Tungpuchayakul, co-founder of the Labour Rights Promotion Network Foundation, a Thai advocacy group.

“It has become an excuse the government is using to justify they have done something, but in practice they don’t use it to solve the problem.”

More than half the estimated 600,000 industry workers are migrants, often from poor neighboring countries such as Cambodia and Myanmar, United Nations data show.

Tracking devices

After the European Union threatened to ban fish exports from Thailand, and the U.S. State Department said Bangkok was failing to tackle human trafficking, Thailand toughened its laws and increased fines for violations.

It banned the use of workers below age 18 and ordered fishermen to be given contracts and be paid through electronic bank transfers.

Authorities ordered Thai vessels operating outside national waters to have satellite communications for workers to contact their families or report problems at sea, plus tracking devices to spot illegal fishing.

“We are serious in law enforcement regarding human trafficking and illegal labor cases,” said a Thai government spokesman, Weerachon Sukhontapatipak. “There might not be abrupt change. … It will take time.”

Thailand is also rolling out an ambitious plan using iris, facial and fingerprint scans to record fishermen’s identities to make sure they are on the boats they are registered with and to help inspectors spot trafficking victims.

Rights groups have tried to use satellites to pinpoint the location of ships that remain at sea for long periods, potentially indicating enslavement.

But human trafficking expert Benjamin Smith at the U.N. Office on Drugs and Crime said that using satellites to tackle slavery at sea is not easy unless there is a lead on where to track a vessel in the vast ocean.

“I think people underestimate the size of the ocean and the ability to pinpoint where something as small as a boat is,” Smith said. “If you have good information, intelligence, then satellite images can be good. … It has to be a small part of a much bigger effort.”

Smith also highlighted difficulties with prosecuting cross-border trafficking and with shortages of maritime police funding, adding that continued consumer pressure on firms to clean up their supply chains could be a potent force to help end slavery. “That’s probably the best way you can start,” he said.

Good news

Fishermen remain at risk of forced labor, the International Labour Organization (ILO) said in March, and the wages of some continue to be withheld.

To combat slavery, firms must improve workers’ lives rather than cutting labor costs and recruiting informally to meet demand for cheaper goods, experts say.

“Smaller owners are getting squeezed, and still rely on brokers and agents, who dupe workers and keep them ignorant of their rights and conditions on the boat,” said Sunai Phasuk, a researcher with the lobby group Human Rights Watch in Bangkok.

Workers are set to become more vocal with the May launch of the Fishers’ Rights Network, which aims to combat abuses, backed by the world’s largest canned tuna producer, Thai Union, and the International Transport Workers’ Federation (ITF).

“Without enforceable rights at the workplace and the strength that comes from being represented by a union, labor rights violations and the mistreatment will continue,” said Johnny Hansen, chairman of ITF’s fisheries section.

Thailand’s ratification this month of the ILO protocol on forced labor also offers hope. It is the first Asian country to promise to combat all forms of the crime, including trafficking, and to protect and compensate victims.

“We have … committed to changing the law to allow workers to form unions so we can work together to solve the problems,” said Thanaporn Sriyakul, an adviser to the deputy prime minister. “But the process is long, and it will take time.”

Thailand has also pledged to ratify two other conventions on collective bargaining and the right to organize, which campaigners say would better protect seafood workers.

This would be good news for Lin’s fishermen’s group, which has helped rescue more than 60 people since 2015, except the group has no legal status because Thai law does not permit fishermen’s unions. This has led rights advocates to use other terms, like workers’ groups.

“There are still lots of victims, and I want to help them,” Lin said. “As fishermen who have suffered in a similar manner, we understand each other’s needs and are able to help better.”