Bimodal steelhead run distribution for upper Columbia tribs

Discussion in 'Steelhead' started by Lex, Sep 26, 2013.

  1. Lex

    Lex Active Member

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    Anyone care to comment on the two peaks of steelhead pushing through? Look at the Preist Rapids counts / graph to illustrate my point. This is called a bimodal distribution and appears to be a consistent phenomenon over the last two years. Interesting thing is that it doesn't pan out over the ten year average. My guess is water temerature of the Columbia and it's tribs.

    Any other insights? SalmoG? Smalma?
     
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  2. Bob Triggs

    Bob Triggs Your Preferred Olympic Peninsula Fly Fishing Guide

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    Links would help here.
     
  3. Derek Day

    Derek Day Rockyday

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    I would guess temps. Last year actually fits the bimodal distribution better, this year more closely tracks the pattern for the 10 year ave. But, I have seen bimodal run peaks (redd counts) that were unlikely a result of temp variations.

    [​IMG]
     
  4. tkww

    tkww Member

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    I don't know about dam counts, but it seems that with just about any Columbia/Snake trib there is a two-pronged influx--an early push and then a later, much bigger push. I've heard/seen this anecdotally. Of course the hard part is not knowing what it means or becomes of it. If the majority of wild fish push into and spawn Jan-March/April, what is wild fish doing there in Oct? Is it going to wait for 3-4 months? Spawn earlier? From another system and will eventually drop back out and continue on? The one thing I will say is that from an evolutionary standpoint, having the fish spawn at different times definitely lowers/spreads out the risk (flooding, etc.).
     
  5. Kaiserman

    Kaiserman Phil 4:11-13

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    Not to over think it, but those spikes happened when we got those flash floods.

    Depending on how far downriver the dam is from the actual rain that fell, it lines up with the timing of the surge of water - which would change the temps I'm sure temporarily.
     
  6. Freestone

    Freestone Not to be confused with freestoneangler

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    The lifecycle that you describes above is a winter run steelhead. They become sexually mature in the ocean and enter freshwater ready to spawn and therefore spend only a brief time hanging around (comparatively speaking).

    The Columbia system only has summer run steelhead, that is, fish that enter the freshwater from early summer through fall. Summer runs are sexually immature when they enter the freshwater and will 'ripen' in the fresh water. However, they spawn at the same time as the winter run fish that are found in coastal and Puget Sound rivers. So yes, these steelhead hang out in the freshwater - not for 3-4 months - but for up to ~9 months before spawning in the spring, after the season closes March 31. They are genetically engineered, so to speak, to swim long distances in the freshwater and be able to hang out and live there waiting for spring.
     
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