It’s looking like another lacklustre year for the Yukon’s chinook salmon, with early estimates ranging from 65,000 and 87,000 for the Yukon River, similar to 2015.
This translates to ongoing commercial bans and subsistence harvest restrictions.
And don’t expect a rebound any time soon.
That’s the take-away from researchers at the National Oceanic and Atmospheric Administration based in Alaska, which helped create the Alaska Department of Fish and Games’ annual salmon outlook.
Since the dramatic decline of the Yukon River’s chinook run in the early 2000s – when the salmon returned to the river at less than half previous average numbers – scientists have been scrambling to figure out why. The list of theories is long, but leading expert Phil Mundy thinks the fact that these are some of the most rapidly warming bodies of water in the world during the spring and summer, according to the latest report prepared by the Intergovernmental Panel on Climate Change, has something to do with it.
Mundy has been studying salmon since the 1970s, previously in the Columbia River Valley where dramatic declines allow him to draw parallels.
Predicting any natural phenomenon is tricky, but climate change is making this even more challenging. Climate could be affecting salmon in more ways than we can count, from erosion, to silt from summer forest fires, to disease, to food supplies.
But making one of the longest freshwater migrations on record through warming waters also just wears them down.
“As the warm weather continues, by the time those fish get up there they will be tired, the faster they burn what energy reserves they have left,” Mundy said.
“They know this from Columbia River, they swim up to the dam, and by the time they get to the top they can’t swim up over it, they just get swept back in an endless circle.
“It’s really sad.”
Scientists don’t have a specific cause of the decline in chinook. There’s no doubt multiple factors are contributing, which makes it really tricky to narrow it down.
Until then, scientists are doing their best to inform effective policy for the more than 3,000-kilometre-long river.
“Fisheries management is about managing people, it’s not about managing fish,” Mundy said.
But that presents its own set of challenges.
“In general, trying to get people to understand they are the last line of defence is the challenge. We don’t have a state trooper forcing people to do anything,” said Mundy.
As salmon populations decline, the ones that prove strongest live to pass their genes on. So, over time, the Yukon River’s chinook run may learn to adapt to warmer waters. But this change isn’t expected to happen soon.
Until salmon can adapt, scientists like Mundy are working to better understand the health of young salmon as they head into the treacherous Bering Sea, as this could help uncover how temperature changes in the Yukon River and its small tributaries are affecting them.
Scientists have found that the number of fall juvenile chinook is linked to their run three years later, making their numbers a relatively good predictor of future runs.
Each year NOAA Fisheries and its partners at Alaska Fish and Game and Alaska Ocean Observing System share predictions on when adult chinook salmon are expected to return to the Yukon River to spawn, which helps regulators on both sides draft policy and brace fishery-dependent communities on both sides of the border.
Yukon chinook is the first major salmon run managed through its entire range: from the accidental bycatch from the Bering Sea pollock fisheries to the 50 or so small subsistence fisheries along the Yukon River watershed.
In recent years the many First Nations communities along the Yukon River that still hold legal rights to fish chinook have voluntarily opted not to in order to help preserve the salmon. This has not been easy, given the cultural importance of fishing, Mundy said.
He recognizes that the burden is disproportionately heavy on First Nations with subsistence fisheries, which have had to change ancient practices because of forces beyond their control.
According to Wayne Jenkins, executive director of the non-profit Yukon River Drainage Fisheries Association, communications between fishers and fishery managers in this region has been key to education and success. The association hosts conference calls throughout the season with researchers and fisheries policy-makers from both sides of the border.
“We’re trying to create the ethic of it’s all one river,” Jenkins said.
Mundy agrees. “Cooperation and understanding of people is what’s necessary. I believe we can hold the line until biology figures it out.”
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