Fish die-off observed near Huslia and on the Kaiyuh Flats
7-20-07
Tim Bodony (KIYU)

US Fish and Wildlife Service biologists in Galena have observed an unusually high number of dead whitefish and pike on lakes and rivers across the region.   

Residents of Huslia have been calling Fish and Wildlife with the same observations. 

Wildlife Biologist Jenny Bryant was among the first to notice the fish die-off last week.  This past week, she flew to a lake, 8 miles east of Huslia, to prepare a site for an annual duck banding project. On reaching the lake, she noticed around a hundred dead fish floating on the water.

At around the same time, a different group of Fish and Wildlife biologists observed a smaller number of dead whitefish and pike on a float trip in the Kaiyuh Flats, south of the Yukon River from the villages of Nulato, Koyukuk and Galena. 

And when Fish and Wildlife personnel from the Galena office visited Huslia on Wednesday, Huslia residents reported different sightings of dead pike and whitefish on local lakes and streams.     

When Bryant and her colleagues brought the fish die-off mystery to the attention of fish specialists at the Fish and Wildlife offices in Anchorage and Fairbanks, they were referred to the State’s Fish Pathology labs.   

Bryant says that the Anchorage lab is looking into the situation, but has not come back with an explanation yet.  But the temperature and amount of water in the rivers and lakes might provide some clues. 

Subsistence fishermen from across the Yukon River drainage have noticed warmer water temperatures this summer.  In reports shared on the weekly Yukon River Drainage Fisheries Association teleconferences, fishermen have shared evidence that king salmon are running deeper and further from the banks than usual, to seek out cooler water.       

And set net users have been checking their nets more often, to prevent fish from degrading rapidly in the warmer-than-average water.   

Bryant cautions that it’s too early to pin down a cause for this fish die-off, but the combination of low water and warm weather is the leading theory right now.  

"High temperatures and low water actually causes an oxygen depletion," Bryant explains, "so the fish run out of oxygen. That's our leading theory right now, but we don't have enough local expertise [to verify that.]  So were are just bouncing areas off of people right now."

Fish die-offs such as this have happened before in the area, and Bryant says that local knowledge seems to confirm a link between a fish die off and warm temperatures.   

"We have witnessed things like this before, but I think this year it was hotter, so it might be a higher magnitude," she says.  "And there is something similar to this down on the Innoko, which was noticed about a week and a half ago."

The State’s Fish Pathology Lab in Anchorage welcomes input and observations from people who have seen unusual concentrations of dead fish this summer.   

Their phone number is 267-2244, or you can contact the Fish and Wildlife office in Galena for more information.