The pinnipeds have definitely learned about these concentrated hatchery releases. They show up the day before the hatchery releases and pound the juvenile fish coming out of the hatcheries. However, as far as we know, that takes only a relatively small percentage of the total smolts released. Hatchery juveniles in general survive at only about half the rates of natural juvenile salmon, which are better adapted to deal with predation risks of all sorts right from day one. The dumb ones get knocked out while they're rearing under natural conditions with high predation risk.
The bottom line is that it's a complicated mixture of impacts.