According to the Thomson Reuters Foundation, 80% of canned tuna brands do not know where their fish is coming from- which puts workers at risk. Only seven firms are able to identify the entirety of their supply chains. Slavery is far too common in the fishing industry. Tuna companies are now being pressured to identify where their fish is coming from, and are failing to do so. The canned tuna industry is growing, and so is the slavery and violence associated with it.
See "Canned tuna brands found failing to combat slavery in supply chains", Lin Taylor, Reuters, June 3, 2019