"Aimed" to death is meaningless.
"Stuck" to death is just wrong. If a knife or a spear is used, the seals are knifed or speared. If a trap in which they are "stuck" is used, they are trapped.
Shot to death is correct if rifles are used.
But in fact the seals are clubbed, as the article says. Therefore the answer is <WRONG: see below> struck, because a club strikes or hits the seals, so as not to pierce the valuable pelts.
PS. I am sorry, sorry, sorry! 90% of the seals are shot.