The habitat is poor for a variety of reasons. Lack of salmon should be high on the list. Among other things, the literature shows they provide nutrients that increase smolt numbers, increase smolt size, increase marine survival of smolts, increase insect production, decrease insect generation time, increase bear productivity, increase mink reproductive success, increase tree growth, remove sediment from the gravel, provide protection of redds from freshet, produce better wine, and I suspect more is on the way.

And, a biologist unfamiliar with the use of and "individual sampler" is not utilizing the best tool available. Too much biology is conducted in front of a computer.