Loc: Somewhere on the planet,I hope
With the rain everyone has hopes that the drought thing is all done, gone, bye bye but the effects will linger. Even with the rain flows will drop down below average again by around the 10th of November according to the Northwest River Forecast Center. So just when you think your safe this will materialize. A retired staffer sent this a bit back and it is about to become relevant.
You noted, correctly, that low flows may not let Coho penetrate as far up the tribs. This means that, for a given spawn, fewer smolts will be produced. In the extreme drought at Snow, more Coho spawned in half the stream. We got half the smolts. Second thing that happened, and this will be critical because they use Index sections to survey, is that there will be more fish in the indexes because they can't get higher. We saw this, too, since we surveyed 100% of the anadromous zone. So, the estimated Coho escapement for 2015 will be reported as a number that is "higher" than reality and this will lead to a larger forecast in 2018.
As to chum, the method I have seen to estimate escapement is a mean number of fish days; how long a live fish is in the index. The number used in PS was around 10. Again, in the drought year, Snow and Salmon creeks had different survivals with Salmon being less than a week. The result was that the official escapement for Snow was higher than the official escapement for Salmon, even though Salmon had about twice as many spawners. We cut tails off of all carcasses so we only counted them once. In another drought in the mid-80s, a stream in Hood Canal never had a single live fish. One week, zero. Next week, post rain, 100 dead. By the "official" method there was no escapement. Plus, chum will also be affected by how far upstream they get. Escapement methodologies are built on averages and average conditions.
Dazed and confused.............the fog is closing in