Abundance of algae found on dead salmon
Hundreds of dead salmon washing up along the Kobuk River appear to be healthy, according to the Alaska Department of Fish and Game's pathology lab.
A carcass collected by a U.S. Fish and Wildlife Service employee last week was sent to the lab for testing and a necropsy. Lab officials ran tests for viruses and bacteria, though those results are still unavailable, according to an update from the USFWS.
In the dissection of the fish, scientists noted that the salmon appeared healthy and was close to spawning before it died.
"The one interesting thing they found was algae (diatoms) on the gills and skin," said Susan Georgette with the USFWS in a statement. "They said there would have to be a lot of algae in the water to stick to fish."
According to the lab, the excess of algae backs up the indication that the hundreds of salmon died from low dissolved oxygen, or Low DO.
"Algae blooms consume lots of oxygen in the water, and combining that with a huge return of salmon could have led to enough oxygen depletion to kill salmon," read the statement from Georgette.
Several types of algae were found, she added, and with the warm, sunny days, the chance of increased algae growth in the river increases.
Fish and Wildlife is now looking into getting the algae tested.
Georgette noted that on a boat trip upriver last week, she and a colleague counted 284 salmon carcasses on a sandbar above Kiana.
"The number of salmon returning to the Kobuk River this year is indeed impressive," Georgette said.
The test fishery in Kiana showed numbers one and a half times higher than last year, which was the second highest, and three times higher than most years since 1993.