Changing/bad environmental factors has hurt the spawning for the last # of years, increased fishing pressure from more people fishing and better equipment (side scanning sonar, internet, etc) and techniques have all combined to hurt the stocks.
I don't know the numbers but the warm waters in the spawning grounds are likely the real issue. Not sure how reduced the spawning population is, but I am hearing that is only a part of the problem.
There will have to be periods when targeting is shut down if they really want to fix this any time soon with what they have the ability to do.
Maybe an El Nino winter will help the water, maybe.