The Northern California Fly Fishing Board

Last Friday and Saturday morning I fished a run on the Trinity River that is about 100 yards long. I found that I caught only hens (4) in the top half of the run and only bucks (5) in the lower half. About the only difference that I could see in the two sections is that the current in the lower half was somewhat slower (water was somewhat deeper). Another angler fishing the same area had 2 hens in the upper half and one buck in the lower half. I'm fairly new to steelhead fishing and wonder if this apparent separation of the sexes usually occurs or if this was simply an unusual occurrence. I was surprised also that the fish were all remarkably similar in coloration and size, the hens being about 24" and the males about 26". Is this common? Thanks for any input.