So what drives the ocean ecosystem and let’s salmon thrive and return in large numbers to support sport and commercial fishing? Forage fish of course play an important part in feeding salmon, but only if forage fish are available in adequate numbers. Forage fish are in danger from over harvest for use as bait, feed for fish farming operations (some reports say it takes 3 pounds of forage fish to grow one pound of farmed salmon), fertilizer, and more.
Read more about the problem and proposed solutions from the Seattle Times:
http://seattletimes.nwsource.com/html/opinion/2018262940_guest23shively.html