Date has nothing to do with the validity of the research. Yes, the steelhead were in a different genus and had a different species name, but that is irrelevant. Stomach content anlysis has not undergone any vast technological reform. You cut the stomach open and examine/identify the contents. The point I was trying to illustrate was that mature steelhead are feecding on aquatic invertebrates, which could explain the initial question posted. Are you suggesting that all research done before steelhead were classified as Oncorhynchus mykiss (in 1986 I think)is useless? A lot of mature steelhead had food in their stomach, regardless of when it was.
And no i am not comparing apples to oranges. A steelhead is a steelhead. the fundamental biology of steelhead is relatively simialr throughout its range. Yes there are phenotypic and genotypic variations amongst populations (heck there is probably phenotypic variation within populations), but the basic biology (such as sexual maturation or digestive state throughout said maturation) of the organism is similar regardless of location of that population. Saying that steelhead research in california is not applicable to steelhead in washington is like saying steelhead research in Washington is not applicalbe to steelhead in Alaska, or vice versa.
By saying the date should raise eyebrows, I was not saying the research is right or wrong. I was simply pointing out that alot of research has been done since on steelhead and salmon, and that a more recent study might be more convincing. I was not trying to discount your point, or personally attack you. I would however point out that atrophy of the digestive tract is found in all pacific salmon species, steelhead, and atlantic salmon during the spawning run. This inhibits the ability of the digestive system to absorb any nutritional value found in items the fish may swallow. I would not dispute that steelhead, especially summer steelhead swallow many items that can be considered food. I am also not stating that the ability to absorb nutrients is prevalent at the same level from watershed to watershed, or state to state. Though I dont know for a fact, I would even venture to guess that rogue river half pounders feed when they are in freshwater. My point is that you cannot assume research done in california 30 years ago applies unilaterally to washington steelhead or steelhead in general. The research though it examines whether steelhead eat, does not examine whether this eating results in caloric intake, and that, I would argue is the point of this debate. I think you have a valid point, but not an "end of discussion" conclusion.
I agree with you Tom, It is wrong to assume that the research applies unilaterally to Washington steelhead. I was simply trying to point out that maybe the reason why a book said stoneflies are a significant source of a steelheads diet, is because that book was refering to steelhead that exhibit the same foraging behavior as the california steelhead, and that maybe there are other places where a 1.1.,2.1, and 3.1 life history is common, and stonflies rather then trichoptera are more abundant.
First step is admitting these crazy fish will do what they will.. bite or not, and confound us all. I have a hunch some steelhead chow every damn thing in their way, some won't touch anything. Some steelhead go to sea for years, some never, some go home and spawn and live, some die, some go to another "home" and make fun there. They will show up in Mexico in creeks that haven't had water for years. They won't show up in prime conditions, they'll show in numbers in poor conditions. Steelhead are solo from the moment they emerge until they spawn. Where do they go, why? Who knows! I love it. The only regional species that confounds your spreadsheet data even more is our sea run char. Where do they go, what do they eat, when, why, how? I hope we never know! The dynamics of life are always changing. Adapt or die, and have multiple back up plans. Mother nature ain't dumb.
The answer: Yes "steelhead" will eat. How do you think we ever got ourselves landlocked "rainbow trout."
Thouse steelhead only have a different name and genus because trout and salmon used to be classified with Atlantic Salmon and Brown Trout. Now these are the only fish in Norht America that have the Salmo name.
Steelhead are listed under two names, one for the coastal rainbow trout ( Oncorhynchus mykiss irideus) which has a origonal range from the Kuskokwim River in Alaska to the Otay River in California east of the Cascades and Serria Nevada. The other steelhead is the Redband Trout of the Columbia River Basin (Oncorhynchus mykiss gairdneri) which has an origonal range of both the Fraiser and Columbia rivers basins east of the Cascades. These Redbanned Steelhead also used to migrate up the Snake River to Shoshone Falls.
Edit- Message to self: Read full post before posting a reply. :beathead On the other hand, the second part of my post is full of info that most people do not know so I will keep my post on the board.