I saw a special on Discovery I think about the decline in seals. They were blaming much of the loss on the loss of herring stocks. The did a study feeding captive seals on herring and another group on some kind of cod fish. The herring fed animals grew much faster and larger. Can't remember everything but the herring stocks around the world are in the same trouble as most of the fish stocks. Alot of herring spawning habitat is now sushi wrappers.