Ethically-minded shoppers might want to think carefully about what tuna or shrimp they put on their shopping lists. According to Justice for Fishers, a campaign run by the International Transport Workers’ Federation, there remains a lack of “robust evidence” that Thailand’s seafood is free of “forced labour” and other forms of exploitation. The South-east Asian nation is one of the world’s main sources of frozen shrimp and canned tuna. But the massive Thai fishing industry, worth around $5-6 billion in exports each year, has for decades been blighted by accusations that workers, particularly f…