90% of Canadian hunters (they're not the majority of the world seal hunters; there's many kinds of seals hunted and none have ever come close to being in danger of extinction) use firearms but often the firearm doesn't kill the seal so they have to move in and use the club, the kind, etc. is regulated by law just like the type of firearms allowed are. The club is supposed to be used in a certain place/way to crush the skull.

All forms of wild/animal hunting are "brutal" if you think about it (Bambi anyone? :-) and there are always bad groups taking too many/trying to get an edge, etc. There are laws about how old a seal has to be (the Canadian ones have to have grown out of their white baby coats) but you know young animals have certain characteristics that are going to be valued (lamb, veal, some coats, etc.) and more costly; anything that is "prohibited" is going to get a certain criminal element trying to get it because it will make more money.