Basically that document points out that about 65 percent of smolts survive to the tailrace below Lower Granite Dam (that's the uppermost dam that the Idaho salmonids and eastern Oregon and Washington salmonids have to deal with, below Lower Granite Dam remain seven more concrete obstructions they have to deal with. So, out of 1 million smolts (for example the McCall Fish Hatchery-not that hatchery fish matter in recovering threatened and endangered fish-would normally release about 1 million smolts into the South Fork of the Salmon River in March. Averages being what they are we could assume that 650,000 of those fish made it to the other side of Lower Granite Dam still breathing and with a pulse. Another thing in that document I shared first above, is that when the water slacked near Asotin, Washington on the Snake River and near the paper mill on the Clearwater River in Lewiston, about 12 percent of the smolts died between there and Lower Granite Dam. You could say, since the numbers aren't as elegant as they should be, that the slackwater (dam mortality) nonnative predators, enhanced number of native predators due to reservoir (more dam mortality) killed about 120,000 of McCall Fish Hatchery's smolts. Same deal with the wild fish and all the other hatchery fish.
The next number that document I first shared with you above points out is the survival rate from below Lower Granite Dam to McNary, which was 73.3 percent. For our purposes, we now multiply 650,000 fish from our previous survival number by 0.733 and we get 476,450 surviving to the downstream side of the concrete at McNary Dam. Meanwhile the Corps would be telling you something completely different, they would say (I'm going to share another document with you so be prepared to scroll, but remember this document is misleading and it is arguably intentionally misleading, but I share it with you because you need to see your own government give two completely different versions of the story of salmon and dams) So you can go here (hint: they have this misleading graphic on page 2, scroll there but first put on your waders) or scroll through this Bonneville Power Administration document that again, is completely misleading when discussing salmon survival rates at the dams (remember that they are giving you the survival rate from one side of the concrete to the other and nothing more, not the entire dam mortality, which is around or above 50 percent depending on the year).
I know photos of sea lions gorging themselves on salmon sell newspapers, but those sea lions at best eat 9 percent of the adult run of spring chinook, and 15 percent of Willamette steelhead, but I don't need to go into these numbers because anything that kills half or more of the salmon is the number one killer of salmon, e.g. you must focus on that if you want to recover the threatened and endangered salmonids. I'm not saying sea lions gorging themselves at below Bonneville Dam and on the lower Willamette aren't a problem, they are. I'm not saying the fish eating birds in the estuary that eat something like 10-15 percent of the smolts in the estuary each year aren't a problem, they are, too. I'm saying they are nowhere near as big a problem as the dams that kill half or more of outmigrating smolts each year and also kill adults on the way back. (yes, I put a link in there so you could verify my fish-eating bird estimate).
Let's go back, this is feeling quite disjuncted, but I think you get my points. These documents (the third one excluded because it is meant to mislead you and Congress into passing laws that might well make salmon go extinct in the Snake River) can possibly lead you to true dam mortality. They said Chinook from below Lower Granite to below Bonneville had a 43.2 percent survival rate and the first document pointed out that 12 percent of the fish died from where the Lower Granite Pool begins on the Snake and Clearwater rivers around Lewiston, Idaho to Lower Granite dam. To make this easy, we said 350,000 died out of our 1 million from their natal streams to below Lower Granite and 12 percent died in the Lower Granite Reservoir. We can infer from that 230,000 of those 350,000 fish died from some other mortality besides the dams, so 23 percent. Now we have instead of 650,000 fish below Lower Granite Dam, we have 770,000 fish about to enter the Lower Granite Reservoir and we end up with 281,105 below Bonneville Dam or really 36.5 percent survival from where the water slacks in the Lewiston, Idaho area to below Bonneville Dam, which would be true dam mortality before we account for delayed mortality and also before we account for the adults that the dams kill.
So, do you think that if we could somehow remove dam mortality from the equation or significantly reduce it, we might have a better chance at salmon recovery?
I see three options that might lead to salmon recovery, breaching the four lower Snake River dams, which 86 percent of fisheries biologists said was the only sure way to recover threatened and endangered Snake River salmonids, or we could create some extremely expensive bypass canals around the dams that also completely mitigate for dam mortality due to slackwater, reservoir predation, or we could move the infrastructure we have in place at the dams to collect smolts for the juvenile fish transportation program (barging fish) upstream to locations on the Snake and Clearwater rivers and all salmonid holding tributaries of the Snake River Basin to collect smolts before they ever experience dam mortality and barge them below Bonneville (also a very expensive proposition and one the federal government never considered). Breaching seems like the easiest route to recovery. You might disagree, but you also might simply choose dams over salmon, which is your right. I do hope that this post helps you realize the unlikelihood of dams and fish coexisting. It really is a question of dams or salmon. I suppose if you completely removed dam mortality from the equation, you might have some success (but that's going to cost more than breaching four dams that don't pay for themselves anyway). What do you think?