Dead fish in a stream have a way of getting lost pretty quick. Often mortality due hooking or exhaustion injury is delayed with the fish being alive but swept downstream before it dies. It should be pointed out that the above hooking mortality study was for winter-run fish, which don't expend as much energy in the fight, relative to summer-runs and live in waters where temperatures are not a problem.

I'm not aware of any hooking mortality studies for summer-run steelhead, but studies on fall chinook and Atlantic salmon conducted during the late summer and into the fall suggest that higher temperatures increase hooking mortality. I would expect the same with summer-run steelhead as well. But on the other hand, the fish isn't throwing a bunch of its remaining energy into reproduction yet. As I recall, there was a temperature threshold in the lower 60s for the Atlantics, above which mortality increased significantly.

You're very likely causing some level of hooking mortality that is similar to, or higher than winter-run and probably temperature driven. Come late Aug./Sept, if temps in your stream climb well into the 60s, you should keep this in mind.