So I just looked up your thread. I read that article when it was first published. And yes, sea lions wreak much havoc on my preferred fishery (Steelhead in the Willamette Basin). All the steelhead I typically target have to navigate the Willamette Falls, where the sea lions are chowing them.
However, it's a difficult situation for me. I love the idea of trapping and relocating the sea lions that have made a living doing this, but as the article described, that don't work. But we had a tiny return of steelhead last year - less than 10% of a normal return. If that happens for a few more years (and this one is looking grim so far - about 50% better than last year, but still way down from normal), the fishery could collapse.
Anadromous fish are tough for scientists to study. So many different things can affect them between the time they head for the ocean and when they return to spawn a few years later, including water flows and temp on the way in, ocean conditions (food, etc.), water flows and temp on the way back, and predators (including gill netters, sea lions, birds, etc.
I sure hope the fish bounce back.