We're pretty bad at managing wild resources, but then again, we're pretty bad at saving them as well. For example, the same marine mammal act which saved sea otters from extinction has also allowed for the overpopulation of harbor seals which is going to drive the southern resident orcas into extinction. And the fisheries systems that we've built to save salmon and steelhead populations have resulted in less genetic diversity in wild populations that make them more susceptible to disease and predation. Not that I have an answer to this, just a little frustrated that we didn't care about this stuff sooner, and had a more developed body of science on how to deal with these things.

Do you have a source for the effect on Orca?

I don't see anything about Orcas there. Am I missing something?

The article mentions orcas slightly, but it is more about the effect of the marine mammal act on salmon populations. The effect on orcas is mostly implied, it is fairly well known that decreased availability of their primary food source (salmon) is causing their near extinction.

Here's another, if you're curious

https://www.nwnewsnetwork.org/post/hey-seals-and-sea-lions-q...

Yes, but otters don’t particularly care to eat urchins.

I can confidently say that I personally saw a sea otter about 15 miles north of Santa Barbara about 5 months ago that was snacking on purple sea urchins. It would go down, come up, do something, and repeat, and I came across several very-recently-eaten purple urchins washed up along the beach on my walk that morning.

I also pretty regularly collect urchins in that kelp forest, purple and red in that area, and the ones the otter were taking were smaller than the ones I would have chosen. So, at the least, there's at least one sea otter that particularly cares to each some sea urchins, and one human that cares to each the others.

They do, just not emaciated zombie urchins.

It is a bottom tier food source and like you say, they don’t like the evacuated ones present in an urchin barren