That's a big part of the problem. Most companies do not make their supply chains public. And even if they did, there are many places for abuses to occur that are not documented or take place far from any type of scrutiny. For example, slaves have been forced to work on boats catching trash fish used for feed at shrimp farms, and migrants have been brought across borders illegally and taken straight to shrimp sheds where they are locked inside and forced to peel. Fishing boats are going farther and farther from shore, sometimes not docking for months or years at a time, creating floating prisons.