For the past two columns, we explored the extraordinary significance of the Saya de Malha Bank, a submerged plateau in the Indian Ocean that rivals the Amazon in its capacity to store carbon. It is home to the largest seagrass meadow on Earth, an underwater prairie that not only acts as a massive carbon sink but also provides sanctuary to endangered species like turtles, sharks, and blue whales.

Yet the Bank remains mostly unprotected, unmonitored, and largely unspoken for. Largely in international waters and far from land, the Saya de Malha Bank sits beyond the effective reach of national governments. This remoteness has allowed more than 200 industrial fishing vessels to operate there with little oversight. It also means it can be a harrowing workplace for the thousands of fishers from a half dozen countries that make the perilous journey to reach it.

With near-shore stocks overfished in many countries, vessel owners are sending their crews further and further from shore in search of a worthwhile catch. And the Saya de Malha is an attractive target. But the farther from shore that vessels travel, and the more time they spend at sea, the more the risks pile up.

Each year, a fleet of several dozen Sri Lankan gillnetters undergoes some of the longest trips made to the area, often in the least equipped boats. In October 2022, a British-American couple encountered a Sri Lankan gillnet boat in the bank. The Sri Lankan crew had been at sea for two weeks and had only caught four fish, so they begged the couple for supplies.

A month later, again near the Saya de Malha Bank, the same Sri Lankan gillnet hailed another vessel, a South African ocean research and supply ship who was on an expedition in Saya de Malha for the environmental nonprofit Monaco Explorations. By this time, the Sri Lankan crew was almost out of fuel and begged for diesel. The scientists did not have the right type of petrol to offer but they still boarded a dinghy and brought the fishers water and cigarettes. Grateful, the Sri Lankans gave them fish in return. Their vessel would remain at sea for another six months before returning to Colombo in April 2023.

Sri Lankan gillnetters are not the only fishing vessels making perilous journeys to reach the rich and biodiverse Saya de Malha Bank. Thai fishmeal trawlers also target these waters, traveling more than 2,500 nautical miles from the port of Kantang. In January 2016, for example, three Thai trawlers left the Saya de Malha Bank and returned to Thailand. During the journey, 38 Cambodian crew members fell ill, and by the time they returned to port, six had died.

The remaining sick crew were hospitalized and treated for beriberi, a disease caused by a deficiency of Vitamin B1 or thiamine. Symptoms include tingling, burning, numbness, difficulty breathing, lethargy, chest pain, dizziness, confusion, and to top it all, severe swelling.

Easily preventable, yet fatal if left untreated, beriberi has historically appeared in prisons, asylums, and migrant camps, but it has largely been stamped out. Experts say that when it occurs at sea, beriberi often indicates criminal neglect. One medical examiner described it as “slow-motion murder” because it is so easily treatable and avoidable.

The disease has become more prevalent on distant water fishing vessels in part because ships stay so long at sea, a trend facilitated by transshipment. Working practices involving hard labour and extensive working hours cause the body to deplete vitamin B1 at a faster metabolic rate to produce energy, the Thai government concluded in a report on the deaths. Further research by Greenpeace found that some of the workers were victims of forced labour.