Trout thriving at Wyoming lake as biologists address winterkill, adjust stocking numbers - Casper, WY Oil City News
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Trout thriving at Wyoming lake as biologists address winterkill, adjust stocking numbers

A cutthroat trout measured at Meeboer Lake near Laramie. (Wyoming Game & Fish Department)

CASPER, Wyo. — The Wyoming Game & Fish Department say that trout are thriving at Meeboer Lake near Laramie after they had “long suffered winterkills, which reduce trout population.”

“Meeboer is a natural, shallow depression with an average depth of only 6 feet,” Game & Fish said. “This makes the aquatic community susceptible to winterkill. Winterkill occurs when fish suffocate from lack of dissolved oxygen, caused when sunlight cannot reach the aquatic plants growing in the water. When oxygen depletion becomes severe enough, fish die.”

Game & Fish say that the lake was traditionally stocked with 25,000 rainbow trout each spring, but that winterkills tended to reduce the number of trout in the lake.  

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“An electrical aerator system installed in 2013 to address winterkill allowed many more fish to survive, but they were smaller than average and had poor body condition,” Game & Fish added. “However, recent reductions in the number of fish stocked each year have trout once again thriving and growing big in Meeboer Lake.”

Laramie Region Fisheries Biologist Steve Gale said that Meeboer Lake rainbow trout saw about two years with good growth following the 2013 installation of the aeration system, but that biologists saw a decrease in trout body condition by 2016.

“The aeration system was doing its job and helping more fish survive the winter, but then we ended up with too many fish surviving annually,” Gale said.

Biologist sample the lake using gill nets on an annual basis, Game and Fish add.

“From 2014-2017 the catch rate was .1 trout per hour,” the department said. “By 2018, it was 3.5 trout per hour, indicating a significant increase in the abundance of trout in the lake.”
 
“In response, no fish were stocked in 2018, and in 2019 the number of fish stocked was cut from 25,000 to 15,000 to continue to reduce the population and reduce pressure on the aquatic insects that trout feed on. At the same time, biologists diversified the types of fish stocked. “

Gale added: “Of the 15,000 trout stocked each year, 5,000 are now Snake River cutthroat trout, with rainbow trout making up the remaining 10,000 fish. This gives anglers a new species to catch at Meeboer.”

In 2018 and 2019, Game & Fish says that the new approach did not appear to improve results.
 
“But this year we finally saw positive results,” Gale said. “In 2019, only 20% of the rainbows were bigger than 16 inches. Now, 80% are at that size or bigger.”

Cutthroat trout in the lake are “also healthy, with the majority larger than 13 inches. The sampling catch rate was lower for 2020, but body condition increased significantly.”

“In 2018, the average trout scored an 80 on the body condition scale, and this year their average score was 97, which indicates they went from skinny fish in 2018 to plump fish in 2020,” Gale said.

Game & Fish say that biologists will continue to run the aeration system and monitor fish in the lake each year.
 
“But the bottom line is that large trout have once again established a healthy population at Meeboer Lake,” Gale said.