I have caught mackerel from a boat off Kinlochbervie, on the north west coast of Scotland. Knocked a couple on the head, cut a fillet off both sides, and chucked them into a pan with butter. They were caught, cooked, and eaten, within 15 minutes.
Incomparable!

JM

[I never gut mackerel, just cut the fillets off, and give the rest to the gulls.]