My OH fishes and caught 3 mackerel, he can't gut them and do whatever prep is needed to make them fit for human consumption, I don't know what I am doing and we would probably lose most of the fish!  As neither of us are really that bothered for eating them I thought the dogs might enjoy it.  I have 3 dogs weighing 10.5, 13 and 15kg respectively and 3 fish all approximately 12 inches long.  Not got weights of the fish but I could get them.
Can I feed them to the dogs?  They are kibble fed.  They do get odd bits of raw and cooked meat. 
How do I feed them?
Can I feed the kippers raw?  Frozen?  Defrosted?  Cooked?  Whole?  Gutted?  With/without heads/fins/scales?  I could use them to make something along the lines of liver cake but I expect that would mean gutting etc.  They have been frozen whole since they were caught. 
Finally how much should they get?  I was thinking of giving them as a meal as a one off so would it be a whole kipper for the meal?  Or less?
Thanks in advance

Feed them as they are but you may find that they will either turn their noses up or if they do eat it may regurgitate it as that happened a few times when I started to give my crew raw fishes !

Oh no! I did not want to see them again lol!!!
I doubt they will turn their noses up though they love fish

Dont worry they soon scoff it up again !!

Gutting as I recall when we caught some on our schooner holiday last year was pretty easy, we just cut the heads off, slit the bellies, and pulled all the insides out. Then the first mate fried them up and we ate them! Yummy!!

Feed whole to the dogs (the head is the best bit) - I feed part frozen as it seems to be easier for them to get a grip on it.  I sometimes buy Mackerel or sprats or sardines at the fishmonger to give to my dogs.  The oily fish are great.  I would feed outside if I were you as they are a bit slippery and can skate around.  Better on grass or on a mat.

Yep mine love frozen spratt lollies.  They are kibble fed, and get raw foods when I get any.

I would just chuck them to them as-is. They'll get the hang of it, and the best part is that it'll probably take them a while so will be giving their jaws a good work out too. With regards to regurgitating, some dogs do, some dogs don't, mine never has and he gets whole mackerel at least twice a week! If it wasn't so expensive I think I'd make up the majority of his diet of fish.

These are big mackerels what sort of weight should be replacing a normal meal?

It's a hard one as they're kibble fed. Depending on the dog's sizes I'd either halve them or feed them whole as one meal.

10.5kg beagle, 12kg springer and 15kg staff.  They get a small handful and small double handful and a slightly bigger small double handful of kibble for each normal meal.

I'd give the staff a whole one depending on how much they weigh, and maybe the beagle and springer can split between the two. For example my 33kg GSD gets two 400-450g ones as one meal.

Thanks I shall get them on the scales - bout 1.5% of bodyweight then.