As Krijack noted, if the forage fish were increased then the predators would switch off to them. It is my understanding that pinniped preferred lamprey to salmon; lots more fat and nutrients. If we want more salmon maybe, just maybe, we should lay off other species. And, in the short term, it may be necessary to control predators in specific locations where they take unnaturally concentrated smolts/adults like at dams.

The unfortunate thing about trying to recover anadromous salmonids is the myriad of factors crashing them, none of them responsible for the whole thing. Take out dams and don't change ocean fisheries (forage fish and the recovery species) and no recovery. Kill off predators and leave the ocean bereft of forage? No recovery.