It's significantly more complicated than "sterility". Deep SS cutthroat, who live here year around, are doing just fine. They have the same basic FW biology as the steelhead who aren't. Deep SS chum and pink are doing pretty well. They share spawning areas with Chinook.

The "problem", in its most severe form, is for yearling or older smolts. Suggests to me that the problem is either some intense predation on the smolts in the Narrows and/or lack of food in the main body of the sound for these larger fish.

Since PS pink and chum seem to be doing OK, and they must transit the same water in the sound it would seem that the problem is not one of water quality (toxin). That is, unless, the toxins are species and life-stage specific.