It will take action by Greenpeace and Sea Shepherd coupled with the non-fishing public's preference for mammals that will force a change. Fish managers are never going to save the whales.

If you breed for old adults it seems you will get just what WDG got with Summers. "More" big fish but less overall. And that was in the the absence of a marine fishery.

I haven't seen the models but if you applied the same survival rates by age at return it seems that logically the proportion of older fish goes up but the total number goes down as the fisheries still take their whack.

If we want the whales to survive they need food NOW. That benefits the whales immediately as some fish that would be caught now become whale food and the number increases annually. The next easiest way to do that is to cut fishing. The next easiest is to massively increase adult returns by increasing the hatchery plants. This will start to benefit whales 3 years post-stocking as that will be when the first adults come back. The way to pretty much guarantee whale extinction is to only work on habitat as that is decades before any meaningful new members will come back.