Thursday, October 24, 2013

A new species in Parshall

     On September 24 & 27, we ran our annual raft electrofishing survey of the Parshall-Sunset reach, AKA the Kemp-Breeze State Wildlife Area. I always consider this to be probably the single most important data set that I collect every year, for the simple reason that it is one of the longest-running big river trout population data sets that exists in the state. Our researcher Barry Nehring was the first biologist in Colorado to start running raft electrofishing surveys, in the late '70's. He had gone up to Montana, where they had figured out how to do it. 1981 was the first year that he surveyed the Parshall-Sunset reach, so as of this year that data set is 32 years old. It's been done the same way, at the same time of year all those years.
     Speaking of Barry Nehring, I often like to say that I owe my career to a series of phenomenal mentors. I did not arrive in this job by the traditional route of attending graduate school in fisheries. Instead, three years out of college when I was trying to figure out my next move, I stumbled into my first permanent job as a wildlife officer for our agency. After five years I transferred into the biologist job. My goal was always to work as a fisheries biologist; I just arrived here via a slightly different route than most. It's not unprecedented - I've got coworkers who took the same route. But what I was getting at, is that I am constantly thankful for the series of spectacular mentors that I have worked with in the fisheries field.  These are guys that I feel so lucky for every day that I have worked side-by-side with. It's the knowledge that I was able to glean off of them that got me where I am today. Barry is one of those guys. It seems that quality mentorship may be slowly fading away in the professional world, and if that's truly the case it's a sad, sad thing.
     Anyway, I digress. I haven't worked up the data yet from the Parshall reach, but thought I would share a couple of things. First of all, it looks like the density for large fish (>14") is as low as it has ever been, and at this point may be flirting with dropping below the gold medal standard of at least 12 fish per surface acre greater than 14 inches. That is really bad news, for a reach of river that not very long ago supported densities in the neighborhood of 100 or more per acre. Numbers of rainbows in that size category are up, which is good news, but browns are way down. I don't have a precise explanation for it at the moment, but we can get into that over the winter.
     But here is the really sensational tidbit that I wanted to share for now. On our first day, the mark run on the 24th, I was working fish out of the tank and picked up this little 3-inch silvery thing. I immediately said "kokanee" because every once in a while we pick up the occasional small kokanee that got flushed out of one of the reservoirs. However, as soon as I said it, I realized that was not what I was looking at. I said, "Wait--" and the other guys on the boat looked, and three of us said in unison, "MOUNTAIN WHITEFISH !?!?"
     We have NEVER captured a mountain whitefish anywhere upstream of Gore Canyon. Thirty years of one of the most intensively studied trout rivers in this state, and not a SINGLE record of a mountain whitefish. Not just in the Colorado, but not in any tributary, any lake or reservoir, nowhere in the Blue River watershed. In the entire time I've been here, I've taken it for granted that Gore Canyon is the natural upstream barrier of whitefish on the Colorado. There are a lot of them below, and there are none above. That is simply the way that it is and what we have observed in the entire historical record. But here was this little three-inch fish in my hand that was very definitely a mountain whitefish, no question about it.
     The weird thing about it is, this is not a species that people move around. When a new species pops up in an unexpected place, it is almost always the result of either deliberate or accidental introduction by people. But I just can't see someone willfully moving mountain whitefish from a lower section of the Colorado to the upper section, and I have a hard time picturing how it would happen on accident.  I didn't know what to make of it, and chalked it up to just one of those crazy anomalies that keeps us humble. A one-time occurrence that I probably would never run across again.
     Three days later, on the 27th, we ran our recap run on the same reach. You'll never guess what we picked up right in the Parshall Hole. Not one - not two - but THREE young-of-the-year mountain whitefish. Three of them. I was just flabbergasted, and remain so today.
     So here is my theory for the moment. We just came through two extremely unusual years flow-wise. 2011 was an insanely high-water year, and 2012 was an insanely low-water year. I think that if whitefish were to make it through Gore Canyon, it would be more likely to happen during high water than low water. I'm thinking that maybe a few adults managed to find their way through in 2011. We have never run across the adults, but now we have found their offspring.
     There is a good lesson in humility for me in this. At some point over the past year, I was talking with someone who told me that their friend caught what he was sure was a mountain whitefish somewhere above Gore Canyon. I don't remember who it was or exactly where the person was fishing. But it was a secondhand report that came to me. Secondhand reports are never very reliable, and I basically brushed it off because there are many examples of incorrect species identification by anglers.  I can't tell you how many times I've talked to people who don't know the difference between a whitefish and a white sucker. So, whoever it was that told me that, if you're reading this please drop me a line so I can get those details again, and you can watch me eat a little crow.
     If whitefish proliferate in the upper Colorado, it could change the ecology of the river significantly. There would be some benefits to the sport fishery and some potential drawbacks. It will be fascinating to see if they manage to get a foothold here. If they do, 2013 will be a milestone marking the end of the "pre-whitefish" era and the beginning of the "post-whitefish" era.

1 comment:

  1. Neat! I bet they used to be in the upper colorado. Many anglers find them to be trash fish but I really enjoy taking a trip to NW CO once a year to fish for them. They can give a pretty good tussle.