Greenpeace activists bring a message to Walmart's home office front door on ocean destruction and labor abuse in Bentonville, Arkansas. Walmart's Great Value tuna is supplied by Thai Union, the world's largest canned tuna company and the subject of numerous investigations into human rights abuses at sea. While Thai Union has taken initial steps toward ridding its supply chains of labor abuses and seeking solutions to destructive fishing, Walmart has remained silent on its role in selling the potentially tainted seafood.