Regional Offices > Casper Region > Casper Region News > Glendo Reservoir Check-up

Glendo Reservoir Check-up

August 30, 2018
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Casper - The Casper Region fisheries management crew, Matt Hahn, Jeff Glaid and Katie Lawry along with fisheries technicians Andrew Annear and Whitney Peters, completed annual monitoring of Glendo Reservoir in August.  As expected, the number of age-3 walleye (15 to17 inches) looked very good.  Unexpectedly though, the age-2 year class seemed to be weak.  Game and Fish stocked nine million walleye two years ago; it is likely that survival of those fish was negligible.  The team collected walleye otoliths, or ear bones, for chemical analysis that hopefully will show us the relative contribution of those stocked walleye to the fishery.  Otoliths will have a chemical “fingerprint” that will show biologists where they originated.  Final analysis of this data will be available later this year once biologists return to the office to conduct data analysis.
Crappie numbers at Glendo continue to be strong with good numbers of 9-to 11-inch white crappie.  Black crappie are present in much lower numbers.
Below are the results from last years trend survey
Following a rebound in 2016, the walleye population in Glendo Reservoir continued to do well in 2017. Over the past few years above average water levels in Glendo allowed for good spawning conditions and recruitment of young fish into the population; including some of the nine million walleye fry from North Dakota that we stocked in 2016. As such, our standard gill-net catch rates increased from 1.73 fish per hour in 2016 to 2.05 fish per hour in 2017, which is even higher than the ten-year average for walleye catch. While the overall number of walleye in Glendo has risen sharply as of late, it should be mentioned that the population boom is currently being carried by a high proportion of small fish. Accordingly, the overall size structure (or the percentage of all walleye in the population over 15 inches) fell from 61 in 2016 to 25 in 2017.

Angling for catfish at Glendo should be excellent this year. Our standard summer gill-netting showed that the abundance of channel catfish substantially increased in 2017 (0.60 fish per net-hour) when compared to 2015 (0.07 fish per net-hour). While we continue to see evidence of some very limited spawning success, our data shows that there has been high survival of catfish stocked in Glendo. Some of the older fish, which are from 2005-2008 stocking events and are now between 9 and 12-years-old, were just over 30 inches and 14.7 pounds! While there are behemoths lurking in Glendo, the average catfish is around 14.5 inches and 1.4 pounds. The good news is that these catfish are growing quickly and the vast majority of them will be in great condition as they take advantage of ample food supplies.
Populations of panfish (yellow perch, white crappie, and black crappie) all slightly decreased from 2016 to 2017 and fishing will likely be more similar to 2015. Although five years of favorable water levels, reduced predator abundance, and the return of very small juvenile gizzard shad worked together to pull panfish numbers out of their 2011-2013 slump, the recent increase in the number of young walleye is probably responsible for the decline of very young (age-0) perch and crappie. Despite this, most walleye are too small themselves to prey upon older panfish and there should be ample opportunities to encounter these fish. The average lengths were 7.4 inches for yellow perch, 8.6 inches for white crappie, and 8.8 inches for black crappie.

- WGFD -

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