Something to keep in mind about "the numbers". Numbers used in management are what can be collected. Catch, escapement. Lie on catch.....As to escapement, you do spawner surveys to count and estimate the escapement. Freshets can blow carcasses out, maybe hide redds, maybe the fish didn't spawn in the index areas.

One pink year I remember asking the filed bio up in Skagit if the run was what I updated. He laughed. He said that, yes, the fish were there. But, that freshet blew the carcasses into the Straits and the number we would end up with would be much smaller.