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Scientists need help studying dead salmon in Yukon area

Fishermen found dead chum salmon lining the banks of the Koyukuk River. (Photo courtesy of ADF&G)
Fishermen found dead chum salmon lining the banks of the Koyukuk River. (Photo courtesy of ADF&G)

Dead chum salmon are lining the banks of one of the Yukon River’s largest tributaries. Koyukuk River residents and scientists alike suspect the deaths are related to the river’s warm water. A team of scientists headed to the river on July 26 to gather data. 

The reports of dead salmon started late last week. One of the most disturbing came from a series of Facebook videos posted by Ricko DeWilde.

“Okay, we’re in Huslia, Alaska, Koyukuk River. Everywhere, dead salmon all over the place out here. I’m going to cut them open,” DeWilde says in the video. 

When he does, he finds eggs inside one and sperm inside another.

That could be a catastrophe out here, because there’ll be no returns,” said DeWilde.

He notes that there are no net marks on the fish, and that the birds aren’t eating them.

“If something is dead like this, the birds will eat the eyeball right off,” DeWilde said.

In the video, DeWilde suspects that there are too many eyeballs for the birds to eat, and he has a theory about why the salmon died: it’s too hot.

“So either global warming is killing them or something is in the water,” he said.

Stephanie Quinn-Davidson directs the Yukon River Inter-Tribal Fish Commission. She saw these videos, and then more people began calling her. They reported dead salmon, salmon polling in large numbers, salmon seeking slower moving water, and salmon otherwise just acting tired. Like this report from Kaltag:

“That person reported that their kids were able to catch chum salmon with their bare hands in the mainstem of the Yukon River because the chum salmon seemed so disoriented,” Quinn-Davidson said.

Quinn-Davidson says that all the signs point to heat stress. The Koyukuk water has been warmer than usual, and the Yukon water temperatures have broken records. Quinn-Davidson asked two people on the Koyukuk to boat around and let her know what they saw. Their report alarmed her.

“Just along one cut bank and one sand bar they counted over 100 dead chum salmon,” Quinn-Davidson said.

The more tributaries they boated down, the more dead salmon they found. And inside the salmon they found eggs and sperm, meaning that the salmon had not yet spawned.

Quinn-Davidson began mobilizing a team. She, along with the Alaska Department of Fish and Game Yukon fishery manager and a UAF fishery professor, are flying to the Koyukuk River. The crew will boat about 350 miles over two days, counting salmon, sampling fish, and testing the water.

But they are just three people on one stretch of river, and the magnitude of the problem is one of the questions that they’re trying to answer. Quinn-Davidson is asking everyone along the Yukon and its tributaries for help.

“The best thing that people can do when they come across a dead salmon is take pictures, examine the salmon, look for eggs, look and see what the fat content is like, if the belly fat layer is missing, look at the gills. Note where you found the dead salmon, take a count or estimate of how many are there, and contact [the Alaska Department of] Fish and Game immediately,” Quinn-Davidson said.

KYUK will provide an update on the scientists’ trip and community reports next week.

The post Scientists need help studying dead salmon in Yukon area appeared first on Alaska Public Media.


Source: npr

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