The SRKWs migrate at least as far south as Monterey Bay to chase salmon. They evolved to eat fish and one has to look at what changes would need to occur.

Say that a 40 pound Chinook contains 40,000 calories. It takes the whale 2,000 calories to catch it. We have reduced the size to 20 pounds. To get the same 40K calorie input they need to catch and eat 2, with a cost of 4,000. So, they need to pull out some blubber, which releases toxic chemicals stored there.

Some sea lions, when faced with a similar situation (poorer quality food) grew to smaller sizes. So, if the SRKWs lost, say 30% of their size they would now be in balance with their food. But, the big, old ones ould just starve.

It is very complex, and we are not looking at it in a holistic way.