All subsistence fishing for fall chum salmon on the Yukon River will be closed again this season in both Alaska and the Yukon.

“We’re well below where we need to be,” said Alaska Fish and Game (AKFG) biologist Christine Gleason.

“We can’t open any subsistence fishing; we can’t open any other type of fishing.”

Fisheries and Oceans Canada issued this information to Canadian anglers last week in an update on Yukon River salmon runs for both chinook and chum salmon.

Final numbers were released for the chinook salmon showing fewer of them than had been expected made it to the Whitehorse fish ladder.

Only 152 had made it through the ladder as of today. The 10-year average is about 860.

Even though it was already projected to be another historically bad run, more fish than last year’s 165 were expected.

“Everybody would like to see a bit more and they’re a bit disappointed with the numbers,” said Luc Laferté, who works as an attendant at the fish ladder. “They came to see a bunch of fish.”

The fish ladder helps allow the salmon to pass safely around the Whitehorse Rapids Dam. A camera catches each fish on video as it swims by to allow for accurate counting.

More chinook entered the mouth of the Yukon River in Alaska this season compared to last, but fewer fish made it to Whitehorse.

“What this indicates is, salmon disappeared between the (Alaskan) sonar and the (Whitehorse) counting station,” said Sebastian Jones of the Yukon Salmon Sub-committee, a non-governmental advisory board.

“We know that nobody was fishing, so that means they died along the way.”

All salmon species are seeing declines in run sizes in the Yukon River, with biologists attributing the issues to everything from high water temperatures, to overfishing, to changes in historical spawning grounds.

AKFG biologist Deena Jallen said she had heard it likened to an airplane losing its rivets.

“You can take out a lot of rivets, but eventually your plane falls apart,” she said in an interview with the Star in July.

Gleason said the issues probably start in the ocean.

“We’ve been in four years of low salmon runs, and we hit rock-bottom in 2021,” Gleason said. “Right now, every indication is showing that it is most likely a marine effect.”

Since then, just about all types of fishing have been closed for just about all types of salmon in the Yukon River. The blip of good news was this summer, when chum numbers met Alaskan goals to allow subsistence harvest – though not enough to open sportfishing.

The chinook salmon run bottomed out last year in terms of how many fish were entering the river from the Bering Sea.

Both this year and last, only about 25 per cent of what U.S. and Canadian biologists agree is needed for a healthy population reached the Canadian portion of the river to spawn.

Initially, Alaska Fish and Game officials had expected the fall chum run to meet targets to at least allow subsistence fishing after the summer chum run exceeded expectations.

Summer run chum salmon spawn in Alaska, while the fall chum make it through to the Canadian side of the river.

Those fish are just now making their way upstream across the border, and biologists have a good idea of how eventual counts are going to shape up.

They use sonar to count the fish at the mouth of the river and several times along the way.

Gleason attributed at least some of the problems to ocean water temperatures, affecting food sources.

“We’re seeing that their stomachs are less full and their growth rates are less and they’re coming back historically small, even as adults,” Gleason said. “And that’s across all species.”

Once the fish get into the river, they have to deal with warm water as well, with this having a distinct effect on the chinook salmon.

These are the largest type and migrate almost 3,000 kilometres upriver during the hottest time of year.

These warmer temperatures affect the chinooks’ energy level, metabolism and immune system, making them less likely to make it upriver and much more susceptible to being attacked by the Ichthyophonus parasite.

Chinook first get this parasite from eating herring in the ocean. A healthy fish can fight it off, but the long journey up the warm waters of the Yukon River can wear them down, says AKFG biologist Fred West, who is working to try to figure out why so many chinook aren’t making it upstream.

West is seeing an increase in numbers of infections in recent years, and he’s seeing sicker fish.

“Last year they were pretty badly infected as far as severity goes,” he told the Star earlier this summer.

The Yukon Salmon Sub-Committee’s Jones says warm water alone can kill a salmon, and can stop them reaching spawning grounds.

“The hotter the water temperature, the faster their metabolism,” he said. “They might even get so hot they have to stop migrating and find some place cool like a small creek.”

At Eagle station, where the fish are counted just before they cross into Canada, Jones said a typical high temperature is about 16 C, with a record high being about 18. This summer, he said temps there were recorded at 22 degrees, which can be lethal for the salmon.

West said earlier in the summer it looked like more chinook were making it to the Eagle station, but that percentage tapered off throughout the season.

Looking at the final counts in Whitehorse, it appears the further upstream, the worse it got this summer.

Chum salmon don’t eat herring and so they don’t have to deal with the Ichthyophonus parasite, and the water has cooled off since the summer highs.

But Gleason highlighted other issues for the chum, including some changes in their historic spawning grounds such as in Kluane Lake where a river changed course and water levels dropped in 2016 due to a retreating glacier.

At the fish ladder in Whitehorse today, Laferté didn’t want the low counts to make people give up.

“We need to hope,” he said.