In the UK, if you buy mackerel from a supermarket then it's likely to be the Atlantic Mackerel, by far the most common of the ten species of the mackerel family that are caught in British waters.
Mackerel are sought after for food either cooked or as sashimi. It consists mostly of red meat and has a strong taste desirable to some consumers. Atlantic mackerel is extremely high in B12. Atlantic mackerel is also very high in omega 3, containing nearly twice as much per unit weight as does salmon.
Mainly in Scandinavia, canned mackerel in tomato sauce is commonly used as sandwich filling.
Because mackerel is quite a strongly flavoured fish, it can take robust seasonings.
Seasonal Information: Mackerel
This information is specifically for countries in the northern temperate zone of the Northern Hemisphere; particularly the United Kingdom, however it should be applicable for northern USA, northern Europe, Canada, Russia, etc.
Mackerel is at its best and in season during the following months: June, July, August, September & October.