It would depend whether the seal in question was part of an endangered species or overpopulation or not. After all, farmers routinely shoot foxes, rats, crows, rooks, etc, even in spring or summer - when they are breeding. When feral pigeons are exterminated for causing disease to 'free range' poltry, there is lttle outcry. Had the seals been endangered, or in population decline, that might have been different. Here, there are areas where there is an overabundance of seals - that's why sightings of orca in those areas have increased; but the occasional kill from an orca won't dent the population. I suspect that, in a fw years, to preserve the health of the population, some seals, like red deer, will have to be culled.