Research by a Washington DC-based organisation which tracks illicit money flows has found that tens of thousands of workers every year on these boats are estimated to be trapped in unsafe conditions.

Hazardous, forced work conditions sometimes akin to slavery have been detected on nearly 500 industrial fishing vessels across the globe – including in several European nations.

It is much harder, though, than you’d imagine to identify those responsible for abuses at sea, thanks to a lack of transparency and regulatory oversight.

That’s according to a new report concluded by the Financial Transparency Coalition, a Washington DC-based nonprofit organisation which tracks illicit money flows.

Working closely with the Associated Press, the study is a comprehensive attempt to identify the companies operating vessels where tens of thousands of workers every year are estimated to be trapped in unsafe conditions.

The report, published this week, found that a quarter of vessels suspected of abusing workers are flagged to China, as well as many to countries including Thailand, Taiwan and South Korea.

The picture is not much better in Europe though, with vessels from Russia, the UK and Spain in particular accused of mistreatment of fishers.

Considering that the research focuses on fishing on the high seas which are traditionally lawless areas beyond the jurisdiction of any single country, it’s clear that the revealing of these crimes is merely scratching the surface of a much wider-spread problem.

Forced labour in the seafood industry is a rarely seen but common phenomenon – and one increasingly recognised as a “widespread human rights crisis,” according to the report’s authors.

Both European and US companies are under increasing pressure to clean up supply chains in labour-intensive industries where worker abuse is widespread.

The Financial Action Task Force set up by the G7 – which includes France, Germany, Italy and the UK – has recently identified illegal logging and mining as a key driver of money laundering.

The G7 has also encouraged its members to set up publicly available databases to raise awareness about the financial flows that fuel environmental crimes.

The seafood industry, however, has so far escaped the same scrutiny, in part because governments often lack the tools to regulate what takes place hundreds of miles from land.