The Puyallups are, or were, heavily involved in the White River Steelhead.

The acoustic tagging data I have seen across species seems to show little difference in downstream survival between hatchery and wild fish of the same species. In fact, hatchery fish will occasionally show higher survivals when they are mass released rather than the volitional migration of wild fish. This would suggest that the losses are predator-based and probably based on (rather) small predator population taking a constant number of fish per day.

Some losses we saw on downstream migration between two traps could be explained energetically by one Great Blue Heron.