I do my smoked mackerel and my tinned sardines with a modified version of the fisherman's eggs recipe here: http://paleohacks.com/questions/32830/does-anyone-eat-sardines-on-a-regular-basis#axzz1pIeCQDlb. I eat this stuff once or twice a week, delish.

Actually, a lot of the sardine recommendations in that thread might help you with your mackerel. Good luck!

Edited to add:

Another thing I do with any tinned fish is to mash it up with hard boiled eggs for a cold salad. Eat it straight or with the crunchy carrier of your choice.

I picked up some wild caught smoked herring on whim and the salt was unpalatable! I immediately wanted to throw it away thinking there was no hope. Instead I threw them in a tupperware container and began to rinse with agitation over and over until the water was only slightly discolored. Then I let them soak for half an hour agitating every ten min until water was discolored then changed the water. At this point the saltiness was more palatable and the moisture was returned to the fish. Repeat this process until desired result is attained then store in oil (seasoning optional) in the fridge for later use or healthy cholesterol cutting snack!

If you eat dairy you can mix with dill and sour cream. Or mustard and dill for a more Swedish version, then eat with sliced cucumbers - it will take the edge off.

Make some whitfish salad with home made mayo

and I found this recipe for a Blind robin scramble on Chowhound:

To make it chop a baked potato into cubes, 1/2 cup of sweet onion, green onions, or whatever you have on hand in the onion family, 1/2 cup of sliced mushroom of your choice, 1 fire roasted bell pepper chopped, 1 can fire roasted tomatoes drained, 1/2 cup of cheese (a strong flavor works best like extra sharp cheddar or parmesean), 6 eggs beaten, 1 cup of milk, half & half, cream, or buttermilk, T hot paprika, 2 T of dried Italian herbs. Put T of butter & T of olive oil in large oven proof skillet add onions and mushrooms and cook until mushrooms are cooked, add potato, tomato, herbs, sweet pepper, to skillet heat through, mix eggs, milk , and cheese, pour into skillet and mix, place skillet in 325 degree oven and cook until eggs are done.

and this recipe from the NYtimes looks paleofiable: http://www.nytimes.com/2011/12/14/dining/smoked-herring-with-fingerling-potatoes-and-chives-recipe.html