Dead fish in Yellowstone River show same cause as last year; number of dead fish declining

Dead fish in Yellowstone River show same cause as last year; number of dead fish declining

Source: Bozeman Daily Chronicle
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By Michael Wright

State officials have confirmed that the same parasite that killed thousands of fish in the Yellowstone River last year is to blame for the relative handful of dead fish that state officials have seen on the river over the last two weeks.

Montana Fish, Wildlife and Parks said in a news release that test results show the whitefish they’ve found dead in the river this year were killed by a microscopic parasite that causes proliferative kidney disease.

Staff floating river sections both in the Paradise Valley and downstream of Livingston have found a total of about 175 dead whitefish. A few of the fish hadn’t died yet, which helped the lab identify the cause of death.

But the overall volume of dead fish is far lower than in 2016, when officials estimated the total death toll was in the tens of thousands.

“Even though PKD was present, it’s clear that this year’s outbreak is far less than what we saw last year,” Eileen Ryce, FWP’s fisheries administrator, said in the release.

After receiving reports of dead fish on the Yellowstone downstream of Livingston, FWP sent staffers to search for the fish. On their first two floats — between Livingston and Springdale — they found a total of 76 whitefish. A float a few days later turned up a similar number of fish.

Floats through the Paradise Valley — from Grey Owl to Mallard’s Rest — turned up even fewer fish. On a float there on Wednesday, FWP found 13 dead whitefish and two dead suckers.

River conditions were worse last year, with near-record low flows and higher water temperatures. Because of better conditions this year and the low number of fish they’ve seen so far, FWP thinks the river won’t see a kill on par with the one seen in 2016.