For 3 years, AP Investigative Reporter Martha Mendoza and her Pulitzer Prize-winning team have been revealing the slave labor that infects the global seafood industry.  In her latest scoop, she and her colleagues have documented workers from North Korea who process salmon filets that wind up for sale in American Wal-Marts.  The North Koreans work in terrible conditions in northeast China, under constant surveillance, and 70% of their sub-market pay goes straight to the government in Pyongyang.