Looks like it will be a self correcting problem.
Blood in the water will attract sharks, sharks will clean out the affected seals.
Sharks may die, or not, depending on the true cause of the sick seals.
Nature cleans up more efficiently than man does.
Too many seals around these days anyway, visit almost any west coast dock and view the damage for proof.
The seals are just a symptom of the problem. Never saw the importance of sharks in the ocean ecosystem, until I was corrected by a biologist about them. They are the cleanup crew for this sort of thing, if it is disease related. If it is radiation related, will be very bad news. All the animals the seals are eating are the source of the radiation. Fish, squid, crustaceans and mollusks. Can easily see how the mollusks and crustaceans are concentrating the radiation. These seals however are fairly far from Japan, so perhaps it was the fish and squids. Otherwise, it would require radioactive rain falling near Alaska.
Darn. looks like I struck out twice on images for this thread.