It is my understanding that the sea lions, at least, use tp prefer lamprey during their spawning runs. Lots more calories per unit. We've rules the lamprey. They eat what is available, and we keep fishing down everything.

If you remember the trophic pyramid, you start with a lot of plants and the work up through herbivores to apex carnivores. At every level you have a lot less organisms because of every loss. Well, if you harvest everything down to (say) 20 % of historic unfished it still stays in balance until you totally protect the apex predators...

Much of what has been said here is, to me, basic ecology that anybody who stayed awake in class should know. May not mesh with policy though.