International rights groups and labour federations yesterday demanded Thailand end a scheme to augment its chronically understaffed and notoriously abusive fishing industry by swapping Cambodian and Myanmar migrants for prison labourers.

In a letter to Thai Prime Minister Prayuth Chan-ocha, 45 organisations delineated how the “ill-advised and rights-threatening” pilot program will only inflict further damage to the $8 billion seafood industry’s reputation.

“Simply replacing vulnerable migrant workers with released prisoners will not solve the abusive working conditions and many other problems present in the Thai fishing industry,” the letter said.

The labour shortage, the letter attests, is caused by low pay and extremely harsh conditions. Migrant labourers comprise 90 per cent of the industry’s labour and surveys have found 17 per cent to be working against their will.

“If this [prison pilot] program goes forward, we will raise our concerns with the United States Department of State as it considers how to assess Thailand’s performance on trafficking in persons (TIP) in the coming months,” the letter warns.

Last year, the United States downgraded Thailand to the lowest possible rating on the global anti-trafficking index.