The water flow is definitely different, so the last stage in the life of the fish living in those areas is different. When we talk about the Discovery Islands, we're talking about those islands between Vancouver Island and the mainland. Usually the fish use that area to migrate up north when they are juvenile and come down when they are adult.
What happens on the west coast is slightly different. We have a population of chinook and coho that spend the first year of their life in those sounds, where there are also farms. In that case, they are not exposed during the migration, but they are exposed during the whole first year of life. I don't think either is good.