no, the "cure" is to keep their numbers to a ecologically sound value.
The reason here is that we are now another predator of the fish; Seals didn't cause the fish to go extinct before man started fishing, it is man as a predator of the fish that breaks the camels back. Like any animal their numbers reflect the availability of food; more fish, more seals; more seals, they eat more fish, less fish, less fishing.
And, since man is more powerful then the seal we can simply monopolize the market by breaking the chain at "more seals". Of course if there was a way to make it so said seals weren't born at all, it might not be as much of a problem (make the seals less fertile?).
Besides-
what about the whales?