When they looked at the sediments in Karluk Lake, on Kodiak Island they were able to look back about 2200 years. Obver that time, the runs showed a lot of variability. The low escapement was about 200,000. The maximum was 4,000,000 or so. All of this variability occurred in the absence of Euro-American logging, mining, development, and other activities. Simply natural response to the environment.

Now, the MSY escapement goal for the sockeye, I believe, is in the vicinity of 1,000,000. Which means that a small scew-up in catching a few too many coupled with some bad environmnetal conditions and you can drive the stock right into oblivion.

A chracterisitc of MSY management is that the room for error is small. Most MSY escapement goals actually represent a small fraction of the pristine stock. There is no room for a poor year in the environment, a flood, or whatever.