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> > What to take from changes of brown/brook/rainbow proportions?

TrowpaNovember 10th, 2008, 9:58 am
Eastern PA

Posts: 31
I know many of the regulars here (ok most) are much more scientific about their fishing than I if I'm asking something that may be an obvious to you -humor me.

The stretch of stream behind my house used to have a mix...(fished there for the past 6 years). The last few weeks i've seen plenty of rainbows (and caught some too :) ) but not seen a single brown trout.

What could be possible reasons for a stretch of stream which used to have a good mix of rainbow/brown with an occasional brookie to go to almost exclusively rainbow? Should I be concerned about habitat/water quality? Is it due to temperatures? water level? time of year? that the fish would segregate themselves out of a particular stretch? Am i just not seeing the browns (could they be hiding while the rainbows are active?)

Main two changes i've noticed from the "norm" is the water is "gin clear" and very low.

Without more data i know a proper diagnosis isn't possible - just looking for info on possible reasons for this change...


LittleJNovember 10th, 2008, 10:58 am
Hollidaysburg Pa

Posts: 251

This is not a scientific comment, but if it has just been that you have seen this change in the past few weeks it could be that the rainbows are on the move to spawn(and have started). At least in the streams that I frequent the rainbows usually are on the move before the browns. The harvey project on spruce creek is a perfect example, throughout the year you will catch a good mix of fish, but with the first hint of fall those rainbows are on the move and that seems to be all you see. It could also be tied to the fact that rainbows seem to have much less trouble "exposing " themselves than do browns.
TroutnutNovember 10th, 2008, 12:53 pm
Bellevue, WA

Posts: 2737
I wouldn't read too much into a shift like that on the time scale of a few weeks. It could have something to do with seasonal movements or behavioral changes in either species.

If you've seen shifts in species composition over a longer time scale, that could be a sign of environmental changes, though there are some other explanations.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
GONZONovember 10th, 2008, 12:58 pm
Site Editor
"Bear Swamp," PA

Posts: 1681
Am i just not seeing the browns (could they be hiding while the rainbows are active?)

I think that's probably it, Steve. With prolonged low and gin-clear water, I suspect that the brown's photophobic and cover-loving tendencies probably account for some of the difference. Rainbows generally seem more willing to feed in open water during the bright part of the day than browns, especially under clear-water conditions.

The other thing that comes to mind is that you might be seeing temporary fluctuations in recruitment. In a mixed trout population like the Little Lehigh's (not just mixed species, but mixed wild and stocked trout), diminishment of a couple of year-classes of wild trout might affect the proportions of rainbows to browns that you see. Browns make up the majority of the wild population, and a few rough seasons for spawning (or for survival of young fish) could influence the ratio. Something like this happened on many of my favorite Pocono streams in recent seasons. Multiple years of catastrophic flooding resulted in a sharp decline for at least two year-classes. I was catching larger wild browns on average, but their overall numbers had declined considerably. I wouldn't expect that effect to have been as severe on the Little Lehigh, but perhaps it was. (Or perhaps it was a compounding influence.)
TrowpaNovember 10th, 2008, 1:08 pm
Eastern PA

Posts: 31
Thanks for all the information guys - this is indeed the most intelligent fishing forum around!

TrowpaNovember 15th, 2008, 9:31 am
Eastern PA

Posts: 31
Just a followup - I fished the same stretch for a couple hours this morning (in the rain bleh!) - water was of course a bit higher and not so clear...wouldn't you know it? bingo - caught a brown.

I suspect Gonzo hit it - the rainbows were just more comfy feeding out in the open in sunny clear water. Even the brown i caught today was tight against cover.

Thanks again...
GONZONovember 15th, 2008, 1:24 pm
Site Editor
"Bear Swamp," PA

Posts: 1681
I'm glad that you turned up a brownie, Steve. You and Jeff had already suggested the possibility--I was just agreeing with both of you!

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