2015 Creel Project - FINAL

    One of the other big questions we are trying to answer with the Creel Project is, "Is there a "Normal", "Standard" or "Typical" run picture?" In other words, what if anything, is common to the runs across the North Shore with respect to steelhead, and what does that look like?
    That picture is beginning to resolve itself in a big way; but the key has been figuring out whether there is a common denominator and how to apply it.
    We have to go back to one of the things that frustrated us initially. That is to say, conventional wisdom at the time was that flow was the be-all, end-all in steelhead fishing: Flow goes up, fish move, flow goes down, movement changes and or decreases. Turns out that what we are learning is while this still holds true, it really depends on for lack of a better description, what stage of the run we are in, and the key factor appears to be stream temperatures early in the season.
    So lets jump into the Way-Back machine for a second. Again, even before we started this project, flow was the thing. Where we started scratching our heads was that we observed a number of runs in which early in the season and just after ice-out, flows were ideal, but you could not buy a fish to save your life. Based on conventional wisdom, we should have been lousy with fish. After logging several runs like this. We began looking closely at the data, but we still didn't have a clue as to why this might be happening.
    It was only after a chance-encounter with one of the Minnesota DNR's technical papers that the light-bulb went on. There was a single reference to initial up-bound migration being influenced by temperature, and this was what sparked the whole Initiation Threshold idea, which by the way is our term for that larger concept, not a technical term.
    From there we dug into all of the Trap data we could find which seemed to confirm the idea, we just needed to plot our own course and start analyzing our own data in the context of the threshold provided in the technical papers.       
    Roughly 10 years and 6 years of specific data later, we think we have validated the concept, and we think it's also important to understand from a steelhead fishing planning perspective.
    If you take all of the creel data, it turns out that we can pinpoint within a roughly 72-hour window the year to year calendar date when each region hit the threshold. From there, we simply shifted the data so that independent of the actual date, May 2nd vs. April 10th for example, the 7-day period of the weekly format aligns around the so-called Initiation Threshold. We call this the "Zero Week".
    Next we plot all of the reported creel catch. The numbers and the dates are not important, we are trying to get a signature. We also calculate how many fish were reported to creel in the weeks prior to the threshold being met vs. how many were reported post-threshold. Pre are all the "negative" weeks prior to Zero Week, Post are all the weeks Post initiation threshold.
    Once we had that, we observed some important things. We also seem to have data which is validated by what we know, based on DNR technical literature, about both steelhead and kamloops.  

    Here we see lower shore returns plotted against the threshold. 7% of the total were reported as caught prior to the initiation threshold being met, while 93% were reported caught post-initiation threshold; these include both steelhead and kamloops. Ignore the "Magic 40" point for now, that is more for a discussion about presentations and a rule-of-thumb.
    When you look at plots of individual years' data, the picture is virtually identical: Typically less than 9% of fish are reported pre-threshold, with the highest numbers reported in the immediate 10-14 days post-threshold. Overall run periods lasting roughly 5 weeks are most common. The only thing we really see changing are the amplitude and length of run. Amplitude is affected by a number of factors such as recruitment, average age of the spawning population, composition and/or ratios of steelhead to Kamloops etc. The length of the run seems to be most affected by the rate at which streams warm. It appears that rapidly increasing average temperatures over time compress or shorten the overall length of time of the run, while more moderate increases lengthen the period of the runs. This is one of the primary reasons we are interested in looking at when creel reports cease as a function of average temperatures.   

    Mid-shore shows a remarkably similar signature although the peak is a little more compressed. It's still to early to draw any kind of conclusion about that with respect to the mid shore.

    Upper shore is also a little different, but the overall signature again is remarkably similar. We do still need more data to flesh out the later stages of the run however, reports from that time-frame are still thin on the ground.

    One thing to note is the lower percentage of fish reported pre-initiation threshold. What we think is going on there has to do with the ratio of Kamloops to steelhead in the creel. Recall that kamloops have a slightly lower run and spawning temperature threshold than steelhead. Since kamloops make up such a small percentage of upper shore creel, it would make sense that less fish are moving pre-threshold on the upper shore in comparison to both the lower and middle shore where the ratio of kamloops to steelhead reported is much greater.

    What we believe it all boils down to is this: The runs have a pretty typical progression regardless of which region of the shore you happen to fish, and this progression is most affected by temperature early in the run. Once the initiation threshold is attained, you can expect a roughly 10-14 day period of heavy up-bound migration. For the remainder of the run, the primary influence on subsequent up-bound movement appears to be increases in flow, which are driven by precipitation events. This is evident when we look at our daily charts and compare daily average flows with creel reports.

    Once the streams reach an average temperature of roughly 55-60 degrees, the fish appear to wrap it up for the year and leave the system, although there's always the chance of catching a few non-conformists after that point; seems like there's a weirdo in every family...

    From a planning perspective, this information is gold. For those of us who don't have the opportunity to fish frequently or have to travel long distances, knowing the point when the streams hit the threshold, then understanding what the typical run picture looks like along with watching the weather, allows you to afford yourself the greatest chance of catching one of these spectacular fish.

Regards and Good Fishing-
Minnesota Steelheader   


Popular posts from this blog

Sucker River Angler Access - NO MORE!?

Sunshine at Last!