You might notice that some salmon fillets have a thin layer of gray matter between the skin and the flesh. This layer is a fatty deposit rich in omega-3 fatty acids and low in the natural pink pigments found in the flesh. To get a handle on how the gray area affects flavor, we oven-roasted several salmon fillets, then removed the gray portion from half of them and left it intact on the others. Only a few discerning tasters noted that the samples with the gray substance had an ever-so-slightly fishier flavor; most couldn’t tell the difference. It’s easy enough to remove the gray stuff by peeling off the skin of the cooked salmon and then scraping it away with the back of a knife, but the flavor difference is so minor that we don’t think it’s worth the hassle.