the mackerel are out in the ocean every year. i rarely see them even at the entrance to the strait (thank god!!!!!). i see tons of them every year offshore. catch enough of them and you'll know right away when you have one on (first hint, no headshakes... just a constant pressure).
when you are sure you have a mackerel... try this: grab your flyline and hold it with your hand.... you will notice the fish cannot pull your arm.... a great lesson in how a fish can pull really hard at the end of a rod.... but literally cannot break you off with a direct connection.
some people think they taste good... i personally don't. they make great blue shark chum though.... and if you like them there's no limit so you can fill 1,000 freezers.