I've just been reading through this post. I consider myself both an animal lover and a lover of nature. I also observe nature and realize that it is inherently cruel even without any input from mankind. Every living thing must die by one means or another and that is as true for a seal as any other species. It may die fom a club blow or a gunshot and we may call that cruel but in it's own environment it will probably not die of old age but in an even crueler way. It will perhaps die from an attack from higher on the food chain such as by a killer whale or a shark. It is even more likely to drown as shifting ice or dipping temperature closes it's breathing hole. It also may starve if it can't find fish. Many species compete for fish including man. As fish grew more scarce man was able to catch even more because new sonar technology made them easier to locate. Bottom drag trawls scooped them up faster but destroyed the fishes food supply on the bottom. While man must bear the blame more than blame is needed to solve the problem. Bottom feeding fish such as cod and haddock must be allowed to re-generate the species before they become extinct. Bottom feeders are the easiest target for seals because they are slower swimmers than midwater and surface feeders. For this reason the seal stock must be reduced for the fish stock to re-establish itself.
I earlier mentioned about how cruel nature itself is and anyone who has watched a hawk snuff out the life of a sparrow or a cat toy with a mouse must understand this. A seal will bite off the tail of a fish so that it can no longer swim when they attack a large school. This will leave the fish still alive for maybe days, unable to move but available when it is needed. The law of the jungle prevails as much in the ocean as anywhere else. The codfish may not be as pretty or cuddly as a baby seal but it's final agony may be even greater.
As for non meat eating humans think about this before you pat your backs too hard: For every acre of ground ploughed many birds, mice, snakes, earthworms, insects, and other ground dwelling creatures lives will be lost. On the other hand a cow may be only one life and feed as many as an acre of ploughed ground. The truth is that we can only survive on this planet by killing something else and the seal hunt, although bloody, may be no more cruel than other fates.