Way back when a drop-out rate of 3% of the landed catch was applied to all (I and NI) gillnet fisheries. I don't know if that is still the case. At one time there was a push to include seal removals. Tribes were not in favor of this because set nets appeared to have more seal losss than drift nets (NI could only use drifts).
Some of the tribes are pushing for a 100% mortality rate on C&R steelhead.
I agree that we need significantly more work on survival post-release. We need to look at how the C&R experiance affects not only survival to spawning but spawning itself. Do they swim as far upstream, do the bury their eggs as deep, are the eggs as viable, does a steelhead successfully become a repeat spawner? This, and more, needs to be looked at.