As a former commercial fisherman...
There are many species that depend on salmon, but what about the species salmon depend on? The fisheries have never been properly run. It's a history of over fishing. Foreigners that have destroyed their own marine populations of marine life are here offering every increasing prices for herring eggs and other marine species.
Herring, anchovies and sardines, primary food sources for salmon and many other species were fished to near extinction, in some cases just for fish oil and fertilizer. Sardine populations have crashed twice in my lifetime. Mainly because fishing was restarted too soon as a political decision to make up for other species populations too reduced for commercial fishing.
The salmon need something to eat in the ocean, here, as they cross the ocean and in Asia. Our salmon travel to Asia every year. Some are caught there. But the real issue is their food sources have been decimated. Even 40 years ago when I fished salmon, in cleaning them, their bellies were often empty or I found things like baby crab from scrounging the bottom. Old, very old timers in the 1970s told me the ocean was dying. When they were young, in the harbors, bays and ocean, so they say, there were never less than 3 bait balls (schools of herring etc., ) visible at all times. In my time the occasional ball was seen. When was the last time you saw a bait ball?
I live on the Columbia. Besides the sea lions, there are thousands of birds that come to feed on the fingerlings at different times. You will see big rafts of sea birds that stay for weeks. I've seen them as far up river as Saint Helens. I don't know how many fingerlings a bird eats a day but collectively it has to be thousands. In a season, millions. Astoria often has 2500 to 5000 sea lions. They don't eat fingerlings but they're here because fish of many species are not abundant in their normal haunts. The solution isn't killing the sea lions or the birds.
My point is, there needs to be millions more salmon spawned. Whether naturally or in hatcheries. Hatcheries probably still only hatch enough eggs to meet their quota. In abundant years the extra fish are not spawned. When I had property with a spawn-able stream and no salmon, the state wouldn't allow a fish box ( for raising salmon from eggs). Over the years hatchery fish become smaller. Streams that can support more than one run of salmon, need to be restored. And we need to increase the food supply of salmon. Not only in the US, but around the Pacific. Asian nations only listen to conservation plans with intense international pressure. They're here buying herring eggs because their own herring is decimated. If we're going to have salmon, sea birds, whales (Humpback whales need herring, too), it's not a simple solution.
When I was very young there was no limit on sport fishing salmon. Later it was 25 fish a day. Now it's none. That's how much it changed in a 70 year life.