Stlhead,
You've overlooked a key point that has consistently limited the alternatives for paying tribes not to fish. Although it is individual tribes that "own" the treaty fishing rights, it is individual treaty tribal fisherman who, with a license from his tribe, exercises that right. So the various purchase proposals end up being befuddled by the "who gets the money?" issue.
If you pay the tribe, then the individual tribal fisherman doesn't receive any direct benefit from such a deal. And the numerous individual tribal fishermen vote on tribal decisions, so they are likely to reject such offers.
I have thought for years that it would make sense to offer to pay a tribe on a given river to not fish for steelhead during a given year. Pay them the market rate for the steelhead they would expect to commercially harvest. [I would propose they go ahead and net those they want for cerimonial and subsistence purposes.] Given the steadily decreasing price paid for commercially caught steelhead, the time should be getting right for this kind of deal. But the problem continues to be, who gets paid? The simple answer would be that the tribe could dole out the payment to individual fishermen based on their % of previous years' catch. But every fisherman is certain that they would do even better than their fellows this year, and won't agree to the % of total harvest they took in previous seasons. (Just like most sport fishermen - we are all optimists, and believe we will do better next time!)
This and the reasons pertaining to quality of the salmon by the time they reach the hatchery, along with the cultural issues, keep ideas like yours on the back burner.
Sincerely,
Salmo g.