Over the past few weeks, Fish and Game has documented dead mountain whitefish on the South Fork and main stem Snake River, and has received similar reports of dead whitefish on the Teton and North Fork Salmon rivers.
At this time, Fish and Game doesn't know the cause of the kill.
"It's particularly interesting in that whatever is going on is affecting only whitefish, and not trout," Regional Fisheries Manager Dan Garren said. "It also appears to be affecting the smaller (younger) fish, generally those less than 10 inches."
Fish and Game has sent numerous samples of dead/dying whitefish to the Eagle Fish Health Lab for analysis, and hopes to have results of those in the near future.
"If you see dead whitefish around the region, it would be helpful if you could let Fish and Game know. At this point, there have been no documented kills in the Henrys Fork, though it is possible that it may be happening there as well. There also have not been any documented deaths of whitefish over 12 inches, and no reports of kills of other species," Garren said.
Fish and Game is also interested in obtaining additional information on the distribution of dead fish and other species that may be affected by the kill.
Anglers are asked to keep an eye out for additional dead fish, and to report their findings to Fish and Game at 208-525-7290. The more information you can provide, such as location, species and size of fish, the better.
"Thanks for keeping your eye out," Garren said.