A recent altercation between fishermen from Thailand and the Myanmar navy has publicized the long-running dispute between the two countries about overlapping fishing rights, experts say.

In the early hours of November 30, Myanmar patrol boats fired on 15 Thai fishing vessels off Ranong province in southern Thailand. One Thai national was killed while four Thai crew members were detained along with 27 Myanmar nationals. One Thai fishing vessel, the Sor Charoenchai 8, was also seized.

Thailand authorities have since been trying to negotiate with Myanmar over the release of the Thai sailors.

Nikorndej Balankura, spokesman for the Thai Ministry of Foreign Affairs, told reporters in Bangkok Friday that the four men were being taken to the town of Koh Song on the Thailand-Myanmar border. “At this moment, the Thai township border committee is coordinating the relevant measures required to send the four crew members back to Thailand,” he said. “It’s being discussed and aim to finalize this process as soon as possible. I sincerely hope there will be good news soon.”

But as of Monday, the four still remained in Myanmar’s custody.

Thai Defense Minister Phumtham Wechayachai confirmed the Thai national who died in the altercation had drowned after jumping into the sea when the Myanmar navy opened fire. The deceased was a 24-year-old who was on his first expedition, reports say.

Phumtham told reporters on Monday that Thailand was still waiting for a reply from the Myanmar military government, and now is unsure of a timeline as to when the four remaining Thais will be freed.

He previously said the firing of shots was an “overreaction” from the Myanmar navy. But Myanmar’s military government maintained it acted correctly because boats were invading its waters.

The regime, which is currently fighting a brutal conflict with pro-democracy resistance groups throughout the country, said it was also investigating materials found on the fishing trawler relating to Myanmar’s revolutionary groups.

Thailand and Myanmar share land borders of more than 2,400 kilometers in Southeast Asia. They also share a maritime boundary of 263 kilometers in the Andaman Sea, which was officially established in 1980 through a bilateral agreement.

But Thai trawlers have often crossed those maritime lines.

Phil Robertson, director at Asia Human Rights Labour Advocates, says the Thai fishermen were illegally fishing.

“The Thai fishing fleets were up to their old lawless ways, conducting fishing in Myanmar’s territorial waters, and this time they got caught by the rights-abusing [Myanmar] navy that shoots first and asks questions later. This latest incident is really a repeat of previous practices on both sides,” he told VOA.

Myanmar’s waters are attractive to Thai fishermen because of the rich fishing stocks available. Thailand’s fishery sector contributed to more than 2 percent of the country’s gross domestic product in 2023.

Dominic Thomson, regional director of Southeast Asia for the Environmental Justice Foundation, says fishing disputes between the two countries have been going on for decades, but this incident is a first.

“Thailand and Myanmar have yet to fully resolve their maritime boundary in the Andaman Sea, leading to overlapping claims. “The tensions over fishing rights dates back to the 1980s when Thailand massively expanded its fishing fleet due to high domestic demand for seafood, coinciding with a sharp decline in fish stocks within Thai waters. Overfishing in Thai waters therefore drove Thai fishing vessels into Myanmar’s Exclusive Economic Zone, often without permits,” he told VOA via email.

Thailand was given a yellow card warning by the European Union in 2015 over its failure to combat illegal, underreported and unregulated, or IUU, fishing.

The mechanism is the first step used by the EU to warn trade partners over their inaction over reducing illegal fishing. If a red card is shown to a country, it means that nation hasn’t made enough progress and its fishing exports to the EU will be banned.

Later that year, Thailand introduced new regulations that said Thai fishing vessels must have monitoring technology installed to warn them when they encroach on maritime border lines.

It is not clear whether these warning systems were ignored, or not active when the vessels were fired at on November 30.

“There have been no reports of similar incidents since at least 2015. The nature of the incident, coupled with the detention of the fishing vessels and crew is unprecedented,” Thomson said.

Robertson says questions remain over how this happened.

“Reliable sources report that there were many more Thai fishing boats engaged in this illegal fishing activity than reported, raising questions about why Thai marine regulatory agencies are failing to ensure their fishing fleets respect Burmese waters. The Thai fishermen look like victims here, but they are the core problem as well,” Robertson added.

Thomson said Thailand must look at its monitoring systems to prevent a repeat incident.

“Thailand should ensure that its monitoring and control systems are adequately staffed, trained and resourced to ensure that Thai fishing vessels that stray into other countries’ waters are told to turn back as soon as possible. It is vital that there are appropriate sanctioning powers in place and consistent enforcement of these powers to deter similar intrusions in the future,” he added.

Thailand is set to welcome Myanmar and other ASEAN nation members to Bangkok in a ministerial meeting on December 20.