This may ultimately prove true, but I will continue to resist the notion that humans and the rest of the Earth can't coexist, because asking people to stop having babies is rather a poor survival strategy, and dooming us all to a fate we can't avoid won't do anything to motivate people to change (which I think we can all agree must happen).

I believe the problem is less about our numbers than it is about profit-motivated greed. No matter how many resources there are available, a few people will always strive to gain control of those resources for personal profit. There are a lot of greedy behaviors we could clean up that would at least prolong the slide toward extinction significantly. Before we throw our hands up and declare the existing habitat isn't capable of more than it currently delivers (and will only get worse until we start killing babies), we should meaningfully reduce mixed stock harvest for a decade or two, to make sure we're right. We've seen plenty of evidence that even the current habitat, given favorable ocean conditions, can still return some very catchable numbers of salmon... especially when NMFS and the Tribes underestimate the run.

If we refuse to change our greedy behaviors, then yes, Humanity and the Earth are doomed.