MPM - You're mixing up allocation and incidental take. They are completely separate.

Allocation is the total number of harvestable fish that are available. Incidental take is the maximum number of wild (ESA) fish that can be killed while fishing for the allocation.

Look at my previous example. The allocation is 20,000 fish, and in reality would like be almost exclusively hatchery fish. The incidental take is the maximum number of wild fish that can be killed while fishing for the allocation. In my example, the allocation is 20,000 (hatchery fish) while the incidental take is 10,000 (ESA wild fish).

JB - You are correct. Splitting the incidental take 50/50 would put a disproportionate impact on the Tribes. That's why it's not done. NMFS splits the take so the State and the Tribe can access their allocation.

The reason they are different is that the State fishes selectively (marked fish only) while the Tribe cannot since they use gill nets. And with gill nets, everything is dead (except in Gray's Harbor) If they used a more selective gear type, they might be able to.