The first chinook salmon is expected to swim through the sonar station in Eagle, Alaska, any day now.
It’s about a 28-day journey from the Pilot Station sonar system, 195 kilometres upstream from the mouth of the Yukon River, in the Bering Sea, to Eagle.
The general assumption by experts is that about 50 per cent of the salmon that pass through Pilot will make it to the U.S.-Canada border at Eagle.
Others swim off into tributaries along the Yukon River in Alaska.
This year, between 130,000 and 175,000 chinook are projected to pass through Pilot, with an estimated 65,000 to 88,000 of Canadian origin reaching the border and swimming upstream, back to their spawning grounds.
Those numbers are above average, but only compared to counts in recent years, said Holly Carroll, the Yukon area summer season management biologist at the Alaska Department of Fish and Game.
The runs used to be much larger – as high as 300,000 at Pilot Station – before chinook stocks took a nosedive in the early 2000s.
“In general, since we saw this great productivity shift occur, we try to talk about things in terms of the run now as below the long-term average,” said Carroll.
“Things have changed. We’re not out of the woods yet but we do hope that this run will be above the recent five-year average. But we’re cautiously optimistic about that.”
In a normal year, the run would be complete, through Pilot, by July 15, but this year, Carroll said the salmon appear to be about four days early.
This is because spring arrived early this year, said Ben Derochie, manager of the Whitehorse Fish Ladder. There, he’s keeping an eye on the Eagle sonar and waiting for the first fish to pass through.
It’s about a 2,800-kilometre trip from the border to the fish ladder. They’ll usually arrive in mid- or late July.
“They’re pretty tired when they get here,” Derochie said.
It takes them anywhere from three days to a week to swim up the ladder to the viewing tank. Then they pass through a gate and staff count each one.
They swim up the rest of the ladder from there.
“Not all of them are necessarily headed down to Whitehorse,” Derochie said of the salmon detected at Eagle. “They’ll branch off to various tributaries along the way and spawn at various spawning grounds.”
Last year, about 1,500 chinook passed through the fish ladder. That’s on par with counts in recent years, Derochie said.
The highest count was nearly 3,000 in 1996, while the lowest was 300 in 2008.
“When it comes to what’s going to happen at the border, it’s very early days for us,” said Carroll. “We are just using projections, using run timing and the count at Pilot, but it’ll be a lot more telling when we start seeing fish at the sonar project at the border.”
The total run size won’t be known until the salmon are counted there.
Contact Rhiannon Russell at firstname.lastname@example.org