In the second half of the program, Chris and Nell speak with Paul Greenberg, the author of the new book, “The Omega Principal, Seafood and the Quest for a Long Life and a Healthier Planet.” Omega 3 fatty acids – or fish oil – have long been touted by doctors and dieticians as a key to a healthy heart and sharper brain. But, what’s the impact of harvesting tons of anchovies and sardines to the marine food chain?