Game and Fish investigates fish die-off on Salt River
JACKSON (WNE) — The Wyoming Game and Fish Department is investigating a widespread die-off of mountain whitefish on the Salt River.
Last week, anglers reported large numbers of dead fish in the river. Fishery managers collected samples, and results are pending at the department’s lab, said Darren Rhea, Game and Fish’s fisheries supervisor for the Jackson region.
It’s difficult to estimate how many fish have died because they’re visible only for a short period of time before being covered up, buried or floating away, Rhea said. He saw a couple hundred dead fish over a stretch of 5 to 6 miles.
There have been similar events in the past in Idaho and Montana, caused by parasites, Rhea said. The indicators on the Salt River seem similar.
Lots of parasites naturally occur in waterways, Rhea said. Under normal conditions, fish are able to overcome infections. But under marginal conditions — including low flows and warm water temperatures — fish are less able to clear infections.
“That’s typically when you see outbreaks,” Rhea said. “When conditions are less than ideal, that can be the recipe to proliferate these kinds of situations.”
If the lab were to confirm the suspected presence of the parasite Tetracapsuloides bryosalmonae, it would be a first for the state. Trout also can be impacted by the parasite, but whitefish are generally more susceptible, Rhea said.
The lab will be testing for other bacterias and viruses.
Fishery managers do not think the die-off was caused by an environmental issue, such as a spill or a leak, which would have a localized impact.
“The fact that it’s widespread throughout the river is a pretty good indication that it’s probably not an acute environmental condition but some sort of other ailment,” he said.
The department will publicize the lab results when they’re available.
This story was published on August 25, 2026.
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