|| Just to clarify, the OU does not have mashgichim watching the tuna -- they rely on a teshuvah of R. Soloveitchik that you don't need to do this. The OU is somech on the government, but the frum world feels that they need to see the OU (much like all our milks now have hashgachot, when the famous teshuvah of R. Moshe means that you don't need a hechsher!) The Star K actually has a mashgiach watching the tuna brought in in Thailand or whereever
Reply: Which R' Soloveitchik Teshuva?
It's a famous teshuvah given to the OU -- R. Schachter discusses it in an article in Mesorah from a number of years ago. When you buy tuna with an OU, the real mashgiach is the FDA!