Supermarkets and fish importers can claim to be shocked and horrified by the headlines about Thai tiger prawn trade slavery, but not surprised. The shameful provenance of the tiger prawns on our shelves has been pointed out to them over and over again.

In 1996, my book The Food We Eat contained three pages entitled The Price of Prawn Farming, which spelt out the environmental and human rights degradation involved in this dirty trade. I leant on research from Christian Aid, and in the years that followed other NGOs stepped in, notably the Environmental Justice Foundation and Fairfood International.

As well as campaigning for years to raise awareness of this scandalous trade, these NGOs confronted fish wholesalers and retailers with the information, often turning up to global seafood trade events, urging them to use their buying power as a force for good.

“Supermarkets cannot claim to be surprised by trade slavery”

Over a year ago, the EJF published a report Sold to the Sea: Human Trafficking in Thailand’s fishing Industry. Also in 2013, the US State Department’s Trafficking in Persons report found ‘57% of the 430 [Burmese migrant] workers surveyed experienced conditions of forced labor.’ It repeated findings of earlier UN reports of prevalent forced labour conditions and debt bondage. It talked of slaves forced to work 18 to 20 hours per day, seven days a week, threatened and beaten, even killed when too weak or sick to work.

Fairfood also reported that the workers in Thai processing facilities were mostly vulnerable women, children - yes, children - and undocumented migrants.

Days before the Thai shrimp ‘revelations’ hit headlines, supermarkets and seafood importers committed to improving working conditions in the Thai shrimp industry at a multi-stakeholder forum on labour conditions organised by the International Labour Organization and the Thai government. This forum produced a draft framework in which joint actions are laid out.

Let’s give the industry the benefit of the doubt: it acted because it was going to anyway, not because it faced bad headlines and needed to deflect them. But it must follow up these noble words with concrete action.

Joanna Blythman is a journalist and author of What to Eat