Bob Weinberger wrote:

The Deschutes is famous for both Redsides and Steelhead. To my knowledge,
they are genetically indistinguishable.

I believe that's right. In general, resident rainbows are genetically
virtually identical to the steelhead in the same subwatershed and
genetically relatively different from rainbows/steelhead in other
watersheds. Not surprisingly, and again in general, genetic differences
between O. mykiss of either form east of the Cascade crest and O. mykiss
of either form west the crest are considerably greater than differences
between O. mykiss from one watershed to the next on the same side of the
crest.

Here's an interesting paper I posted a couple of years ago here, I
think, on genetic differences between various steelhead ESUs:

http://www.nwfsc.noaa.gov/publicatio...7/genetics.htm

Some Steelhead fingerlings never go
to sea and become resident Redsides and some Redsides go to sea and become
Steelhead. Several other rivers in the vicinity have the same situation.
The reason some rainbows exhibit anadromy, while others in the same system
do not, is a mystery to fish biologists.

There's some thinking--but no experimental evidence as far as I
know--that environmental factors influencing levels of competition for
food may play a key role. Greater than normal levels of competition for
food may induce somewhat higher rates of smoltification in offspring of
resident fish; lower levels than normal may result in more "anadromous"
fingerlings staying resident.

You getting to the Owyhee much?

JR