Collection: Collecting mackerel as bait is simple from a boat.  Mackerel can be pulled out six at a time on a set of feathers (Hookai are good but keep the hook size down to 2/0) if you hit a shoal.  Six mackerel is the "full house" - when jigging with feathers for mackerel, keep jigging after you feel the first thump... so that you fill all the available hooks.  Shoals of jellyfish, trails of tiny bubbles on the water surface, oily patches, whitebait skipping right out of the water, fast moving porpoises, birds feeding feverishly, gannets diving into the sea (guaranteed!), and even current lines of flotsam and seaweed are all good signals.  You don't need a fishfinder!  Mackerel can be caught on the surface, at midwater, and at depth.  Bad weather will often break up the shoals and scatter them all over the place.  In these conditions it can be a case of "gold is where you find it" and scent trails are a key tactic. The first fish cut in stripes can catch you a boxload.  Mackerel will move inshore as early as April in good weather, although it may be later the further east/north you travel in Ireland.

Storage: Mackerel will go off very quickly if exposed to the air, never mind direct sunlight.  The cooler box is ideal for freshly caught fish.  Failing this, some wet sacking thrown over them in a fish box is a good alternative.  Mackerel freeze well, however if you want to keep them in prime condition, get them into the freezer fast and never gut them.   This also applies to mackerel stored for the table, although there is just nothing as wonderful as a barbequed fresh mackerel - clean it, drop in a slice of lemon, salt and pepper, wrap it in silver foil and salivate!  I am told that wrapping it in brown paper and keeping it in a cold dark place also works for just - one - day if you have no freezer locally. The local guesthouse, hotel or neighbour will often store fish for you...

Bait Presentation:  Mackerel will catch everything.  Small half inch (1 cm) wide strips cut from a fillet, maybe one or two inches (2-3 cms) long will hook lots of smaller fish, down to dabs, blennies and lesser weever fish.  Some angler swear by using the silver belly for small strip baits; - others use the full strip from back to belly.  Make sure there is skin on a strip bait - as the skin gives the hook its purchase.  If bait is limited, consider using the thin silver belly strips for small fish baits.  This leaves you the option of using the rest of the fish for legering for big fish like conger. A large strip or half a fillet will attract ray, bull huss, turbot, bass, smoothhounds, dogfish and tope, depending on the mark. Moving up to a bigger size bait, half a mackerel (cut at a slant across the middle to give you two equal baits, head and tail with equal portions of the guts in each section) will attract larger fish to bite...  Make sure to remove the tail from all fish to ensure the bait do not spin like a top!  A "flapper" is a whole mackerel with the backbone removed, where the fillets flap around in the current generating a strong scent trail and a moving target.  This will attract really big fish.  It's wire trace time!  Finally for big skate, shark, big tope, and other large critters, a full mackerel, with a few punctures to release the scent trail or aided by chumming, will bring on big fish.  Remember to snip the tails off the baits!  Mackerel cut in strips, fillets and even as flappers are often added to lure baits, and they prove an irresistible combination.  

For reasons best known to car mechanics... it has become popular to add WD40 oil as an attractor to fish baits, and although I have never tried it myself, it works... apparently!

Rigs or Traces / Fish Species:  Mackerel will catch anything swimming... and they are great fun as a target fish on light tackle too.