CODY - Thick ice coupled with prolonged snow cover over the winter has resulted in a winterkill of fish in Renner Reservoir near Hyattville.
Sam Hochhalter fisheries biologist with the Game and Fish said a near complete die off was detected during a recent sampling effort. “In years past, we would collect 1,500 fish including sunfish, bass, and grass carp in one hour of sampling. This year we collected a total of eight sunfish,” Hocchalter said. “From an angler’s perspective, Renner Reservoir is essentially fishless.”
“Most years ponds in the Bighorn Basin do not experience any winter kill and other years it’s only a partial kill involving a few hundred fish, which is often an undetectable reduction in fish density by anglers,” said Hochhalter. “Pond Five near Lovell for example experienced a partial winterkill this year.”
Winter kills are natural events that occur primarily in lower elevation ponds and reservoirs during winters with heavy or consistent snowfall. As long as ponds remain snow free during the winter, sunlight is able to penetrate the ice allowing aquatic plants and algae to live and provide oxygen to the water through photosynthesis. If the ice gets covered with snow, plants and algae die. Decomposition of the plant material consumes oxygen which can lead to some fish dying. The dead fish provide more biomass for decomposition which consumes more oxygen.
“If this condition persists long enough, as was the case this past winter for both Renner Reservoir and Airport Pond in Worland, oxygen levels can get so low that all of the fish die,” Hochhalter said.
“Game and Fish have stocked catchable and brood cull trout in Airport Pond in Worland and Pond Five near Lovell,” Hochhalter said. “Efforts are underway to stock trout in Renner to fill in the void until the bass fishery can be reestablished.”
(Contact Tara Teaschner at 307-527-7125)