ZoZo,
The idea of selective fishing with traps has been kicked around for some time. The Canadians are doing testing on the Fraser River and WDFW has a floating trap they are testing on the Skagit River. The fish ladders on dams would be an easy conversion to selective fish trapping. From what I have read, the tribes have rejected this harvest method. I have never heard from them exactly why they reject it, but I think it has to do with the ownership of the catch. A tribal member can put together a set gillnet on a low budget and catch fish for which he gets the money. If you harvest the fish in an expensive trap, which would be financed by the tribe and manned by a few, or harvested the fish at the hatchery, who would get paid for the fish? The only fair thing to do would be divide the fish and money from sold fish between all tribal members. Evidently they don't want to do this. IMHO this is unfortunate becuase we need selective harvest and trapping with communal distribution is more in line with their traditional culture.
One more thought on harvesting salmon at the hatchery, the farther up the river the fish get, the lower in quality table fare it becomes.