Sunday, April 28, 2013

Colorado River: Lyons Gulch and Catamount

     Last week we spent our first four-day stint of the year running electrofishing surveys on the Colorado. We use two rafts with electrofishing gear, working in tandem because of the size of the river. There are three people on each raft, so it takes a crew of six. This is an annual team effort with my downstream counterpart out of Glenwood, Kendall Bakich. We have set up four, two-mile reaches on the river that are roughly equally spaced, between Pumphouse and Dotsero. We're surveying all four of them this year. We use a mark-recapture method of population estimation, which means that each reach takes two days to complete - a mark day and a recapture day. 
     We're working downstream to upstream, so first on tap was the Lyons Gulch station. This is about six miles upriver from Dotsero. We've been surveying this reach only every other year. We surveyed it last year, but did it again this year because there was a horrendous, catastrophic flash flood event in the area last year, in early July. So, it just so happened that we had good data showing what was present prior to the flood event (in April 2012), and now we have good data from April 2013, after the event.
     By pure coincidence, I happened to be in Glenwood Springs on a family trip the weekend that flash flood occurred last summer. I've never seen a debris flow like that. It looked like a volcano had erupted somewhere upstream. After about 24 hours of solid debris flow the fish carcasses started coming down. There were tens of thousands of fish carcasses on the surface of the water, flowing through Glenwood Canyon. I've never seen anything like it. It was astounding. 
     You can see the remnants of that flood event if you drive the river road up from Dotsero. From approximately Deep Creek to Red Dirt Creek, every nameless gully coming in from the north dumped massive amounts of material. The size of some of the boulders that moved is impressive.
     Anyway, in kind of an ironic way we felt lucky because this is a rare opportunity to observe firsthand what changes have taken place in the fish populations as a result of such a huge disturbance. Needless to say, the fish population is way down. On our mark run on Monday, in our boat we only handled about 130 fish. That is an extremely low number to get from two miles of river on this type of a survey. We don't have any of the data worked up yet, but when we do it will show big reductions of all species. (Except for rainbows - Kendall stocked a bunch of catchables after the flood to provide some kind of fishery. They're still around.) The thing that was the most interesting to me, though, is that the species composition seems to be approximately the same - all the fish that have been present in that section are still there: whitefish, browns, flannelmouth suckers, white suckers, and hybrid suckers. It's just that all their numbers are down drastically, across the board. I had some expectation that the flood would have affected different species differently and that we would see an altered species composition as a result. But that doesn't appear to be the case. So the good news there is that everything is going to come back; it will just take a few years.
     Catamount was beautiful as always. I really enjoy that section of river. Numbers of fish were impressive and we finally enjoyed some decent weather. Below are some pictures, courtesy of Mike Kline, of the Catamount run.

We did find a few wild rainbows like the one above. Look at that nice white tip on the anal fin. We don't stock fish anywhere near this stretch.

Ahhh, springtime on the river.

     This week we'll continue upriver to our two upper stations: State Bridge and Radium. The State Bridge station is brand new- it's never been surveyed so we have no data at all on what the fish populations are in that section. We decided to add this one because it splits the difference geographically between the already-established Radium and Catamount stations, and because the new ramp at Two Bridges north of Bond is changing traffic patterns on the river. The section from State Bridge through Bond is suddenly far more accessible because of the new ramp. This will only increase as float fisherman continue to realize that they can separate themselves from the whitewater crowd on this reach. So, we want to get a handle on what the fish populations look like there, and if they undergo any changes over the next several years.
     I've had some good comments and questions lately. Keep them coming. I'm saving them up for a slower week when I'll do another "grab bag" and address a few different topics that you have brought up in the comments. As I've always said, this thing will be much better if there is two-way communication going on.

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