Spawnout you say;
The habitat was not destroyed on the Toutle system, only temporarily impacted, except of course for the man-made sediment detention dam.
And then you say;
The Toutle experience was one of the most enlightening events in fisheries management - basically the system was closed to fishing after the eruption and left to it's own devices, and by 1985 there were more wild steelhead in the system than ever recorded prior to the eruption. Then we planted fish, opened it to fishing, and the runs went back down to mediocre at best. Pretty good case for hands-off steelhead management if you ask me.
If that was true, where could they have possibly come from?
I am curious how you have come to that conclusion.
It would seem to be almost impossible for the Toutle to have those kind of numbers of wild steelhead 5 years after the eruption (1985). Since the eruption, and the completion of the sediment dam, there has been like 0 habitats for steelhead to successfully spawn in the main steam Toutle, and another 0 in the entire North Fork of the Toutle. When you look at the picture below that was taken in 1985, you can kind see what I mean!
To this day, the main steam and the North Fork it is still 100% silted in, and only the upper reaches of the South fork and a few tiny feeder creeks has any spawning habitat left for steelhead to even spawn in.
So where in the world did all those "wild" steelhead come from back in 1985?
One must draw the conclusion that any meaningful production of "wild" steelhead must be occurring from the secondary feeder tributaries such as the green. Or maybe all of that "wild" steelhead production that you were talking about that you saw in 1985 was just nothing more then just unmarked hatchery steelhead. If memory serves me, they were not marking the hatchery steelhead in 1980-1990.
This information even further brings into question that any wild natural production was the reason for any such numbers of wild steelhead returning to the Toutle system at that time period:
"More than 150 cross-sections of river channels are surveyed regularly to determine areas of erosion and deposition along rivers draining Mount St. Helens. These repetitive surveys measure bank and channel erosion and channel deposition at specific locations. Repeated aerial photographs also are used to identify sediment sources and sinks. In many places since the 1980 eruptions, channel modifications have been equal to or greater than those resulting directly from the damaging lahars on May 18. Generally, erosion and sediment transport by channel widening and downcutting dominate the upper reaches of the drainage basins, and aggradation and sediment transport dominate the lower reaches"
So do you still believe in what you said when to stated this?
Then we planted fish, opened it to fishing, and the runs went back down to mediocre at best. Pretty good case for hands-off steelhead management if you ask me. Given the same scenario on our few remaining rivers without dams or significant channel alterations I suspect that wild steelhead would recover in a couple of generations, enough to provide C&R on a limited basis.
If so, can you explain how a river that has no spawning gravel, has high water temps, and has huge turbidity problems can possibly produce more wild steelhead then it did when it was in almost pristine condition?
Cowlitzfisherman