My 'guesstimate' of missing persons may be too high, but ...

Leaving aside the 1841 census in which the data are not there. in 1851 and 1861 there are over 300 females listed as Head of Family, married and no husband present.

A more extensive search would now doubt show up those listed as 'Wife' with no husband present.

Some of these 'missing' husbands were no doubt 'abroad' - England or foreign - but I assumed the majority were fishing.

A really extensive analysis would be required to find 'missing' sons.