sorry I was specifically talking about Fraser sockeye.
Re: the "extinction cliff". Thirty or so years a go I remember reading a paper on negative factors on salmon abundance (climate change, ocean acidification, habitat loss etc)
Basically the predicted cycle was for year some periods of relative abundance vs others of scarcity. You could relate these to ocean cycles like El Nino vs La Nina. For each repetition of the cycle the relative levels of abundance would be less than previous cycles. As decades passed the lean cycles, like 2016, 2020, 2024 - which is I believe the least abundant Fraser cycle - numbers would drop to very low, close to nil and then nothing. Much like the pattern we've seen for Cultus and Sakinaw. I believe Sakinaw now has no sockeye returns in it's cycle years that were low abundance. Imagine the same thing starting to happen with runs in the Fraser. It's getting close with the early Stuart runs.