Curt, a good introduction to rainbow trout (Oncorhynchus mykiss) life history, It raised a few questions that I have been thinking about. Understanding rainbow is a good first step in understanding the genus, salmonids, and what the meaning of recovery might be. Early in the discussion you pointed that rainbow in our local rivers are not "residuals" but a rainbow that is not anadromous. You also mentioned the high level of plasticity of rainbow. A knowledge of phenotypic plasticity, the ability for an organism to express properties such behavior, development, or morphology in response to environmental factors is essential to understanding how populations will respond to recovery efforts. It is apparent that in the genus Oncorhynchus, particularly rainbow, cutthroat, and to some degree coho and chinook, the anadromous form is a phenotype that is determined by environmental factors.

Question #1;

What is the sex ratios of the resident rainbow in our local rivers? Are there sufficient numbers of females to maintain the population in the available habitat without the input of anadromous females?

I think the answer to this question can provide some insight towards what environmental factors are influencing steelhead populations. A given population will grow to the size that its habitat can support, carrying capacity. As you pointed out stream morphology is important for rainbow winter survival. The availability of food and spawning habitat are other determining factors. Individuals within a population compete with each other and they disperse to fill all the available suitable habitat. Throughout the great basin, the Elwha above the dams, and many places in the west there are wild populations of rainbow whose dispersal is blocked by physical barriers. In Alaska's Bristol Bay area there are healthy populations of rainbow that could be anadromous but it seems that habitat and environmental conditions are such that the anadromous phenotype is not expressed.

Question #2;

Why are Puget Sound steelhead runs doing so poorly while it appears that the resident form of rainbow is increasing in numbers? Is it because freshwater environmental factors favor the resident phenotype or is it a barrier to dispersal that the anadromous phenotype encounters?

I would think that in a system with a healthy resident rainbow population the number of spawning steelhead would determine which phenotype would dominate. The resident rainbow and the steelhead juveniles share the same habitat and have similar requirements for development. Because of the size and age structure of the resident rainbow they are probably more efficient competitors. A larger number of steelhead juveniles could override that advantage. I don't think then that it is a freshwater environmental factor that is determining the phenotype response. I do think there is a physical barrier that the anadromous phenotype encounters that is often over looked. That is the transition from fresh to saltwater that the smolt undergoes and the physiological change it entails.

Question #3;

Are you familiar with the recent OSU study, ( Smolt Survival ), that found 50% to 60% of the steelhead smolts reaching the estuary disappeared within hours of reaching the saltwater? Is this a high number or would this be considered normal?

The quote below is from the article describing the research.

"If the mortality rate of juvenile steelhead is atypical, it could be increasing because of some environmental factor -- warmer water, more parasites, chemical contaminants, or higher acidification of ocean waters coming into the estuary, for example.

Or predation may be higher because of more seals, sea lions and seabirds."

If the mortality rate is atypical I tend to think that environmental factors are the cause, predators have been around forever. Environmental factors bring us back to phenotype plasticity. The real question is how do environmental factors determine phenotype. How is it that some genetic characteristics are selected and other suppressed. It is a physiological process, the endocrine system determines development, behavior, and morphological characteristics, enabling some gene to be expressed rather than others. If you have seen my recent posts you know I have interest in this aspect of fisheries science. It would seem that there are two possible ways to explain how the environmental factors could determine smolt survival. The transition from freshwater to saltwater is a major physiological transformation. It is mediated by the endocrine system, if the endocrine system is not adapted to the changing environment and can't compensate for the conditions encountered the smolts will die. Given the high plasticity of rainbow trout I don't think that this is the case. The other possibility is that the endocrine system has been compromised. That can happen if the parents of the fish were exposed to chemical contaminates. If the endocrine system is compromised such that smolts entering saltwater have a high mortality the anadromous population will only continue to decrease.

Question #4;

Did you read all of this?

If you did any comments would be appreciated, I am sure 34 years of experience provides some insight that can't be gained at the library or on the internet. I do think that rainbow trout are a model we can use to gauge results of salmon recovery. The hundreds of millions of dollars spent on recovery are often directed at programs without regard to the plasticity of Oncorhynchus.