Elko County, NV: On Friday, April 8, the Nevada Department of Wildlife (NDOW) received reports of numerous dead fish at Wildhorse Reservoir in northern Elko County. After surveying the area, NDOW biologists have confirmed that a die-off event occurred, impacting mainly yellow perch and a few channel catfish and trout.
The lake was mostly ice-covered earlier in the week on Sunday, April 3. Due to increased air temperatures and high winds, the reservoir was completely free of ice by Wednesday. Biologists believe the rapid loss of ice coupled with high winds led to a turnover, depleting oxygen levels in the deeper water areas the yellow perch occupy. Low oxygen levels in lakes and reservoirs can also occur while waters are ice-covered, as limited sunlight causes aquatic vegetation to die and decompose, using up available dissolved oxygen. This may have also been occurring under the ice, initiating the die-off, which was likely worsened by a large population of yellow perch and low water levels.
“A fish die-off is a common, naturally occurring process. In this case, it could alleviate the impact of low reservoir levels on other fish species and give them more space to grow,” said NDOW Biologist Fisheries Biologist CJ Ellingwood. “Since the reservoir was overpopulated with yellow perch, this die-off is not expected to hurt the health of the overall fishery. It may actually help Wildhorse in the long run as low water conditions are expected with ongoing drought conditions.”
Biologists will continue to monitor Wildhorse Reservoir for any new developments.