Freespool,

Both over-harvest and poor ocean conditions contribute to reduced survival, that is, fewer recruits returning from the ocean, or even the rivers themselves in the case of in-river harvest, to be part of the spawning escapement. The significant difference between over-harvest and ocean conditions is that we have the ability to influence harvest, but we can't significantly affect ocean survival conditions.

Your point about the CR is a different kind of example where it appears that harvest is having little effect on recruitment, whereas ocean conditions have a major effect. Let me remind you that passage conditions at dams, or the lack thereof, is a form of harvest (i.e. human induced mortality to fish). In some years the dams harvest a far greater proportion of the runs than do the ocean and in-river fisheries. Reducing dam harvest mortality has the same effect as having a high ocean survival cycle.

The upshot is that many variables are capable of being the limiting factor for fish populations. Which factor for any given species and cohort year varies and continues to keep the subject complex and elusive of any simple explanations.

Sg