A bright light may be emerging out of this summer's run of Yukon River chinook salmon.

Counts of chinook at the lower part of the river to date are suggesting a run that is stronger than expected.

It may even see enough salmon – 42,500 – reach the Yukon to meet spawning objectives here for the first time in three years.

The preseason prediction by salmon scientists on both sides of the border placed the total run at somewhere between 60,000 and 121,000 fish, with the likelihood of it coming in at the lower end, perhaps even the worst migration on record.

Alaska scientist Stephanie Schmidt explained this morning the counts at the Pilot Station sonar near the mouth of the Yukon River are encouraging so far.

Now it looks like the return of chinook could come in at that high end of the range, though Schmidt issued caution, indicating there is inherent uncertainty that goes with predicting run strengths.

She said the most recent prediction, however, carries a confidence level of 90 per cent.

"But it is a pretty big range,” she said. "It could be as low as 96,000 or it could be a bit higher than the 121,000.

"But we know we are not in that dire situation we were predicting preseason, which was the lowest run ever. We are fairly confident we are beyond that.”

Schmidt said not until the chinook pass the sonar at Eagle, Alaska just below the Yukon-Alaska border, will they get a more accurate estimate of the total run.

The Pilot Station sonar near the mouth is in a wide section of the Yukon River, and there are multiple species of fish going by, she said.

Schmidt said the Eagle sonar provides a much clearer picture of the chinook run.

The run, she said, still has the potential to be below average, but strong enough to meet minimum spawning goals of delivering at least 42,500 to the border.

Last year, just over 30,000 crossed into the Yukon, and 34,656 the year before.

In fact, fewer than 42,500 chinook have reached the border in five of the last seven years.

The chinook salmon migration has been in decline over the last decade and more, and scientists admit they don't know why.

There's been no sport nor commercial chinook fishery to speak of on either side of the border for several years, and again this year.

For the first time in history, Alaska's subsistence fishery has been closed this season.

The Yukon's aboriginal food fishery has also been closed this summer, for the first time in history.

The Yukon Salmon Sub-Committee, with the support of Yukon First Nations, wrote federal minister Gail Shea of the Department of Fisheries and Oceans early last week asking her to implement a full closure of the aboriginal fishery this summer.

Letters were sent out to the First Nations last Thursday and Friday indicating a full closure would be in effect, Steve Gotch, the local regional director for fisheries, said this morning.

Gotch said the closure will remain in effect at least until officials can determine if enough chinook have crossed the border to achieve spawning objectives.

They're not expecting to be in that position until mid-July, he said.

"Fisheries and Oceans Canada will monitor the return of chinook salmon into Canada via the Eagle Sonar Assessment Program located downstream of the international border,” says the letters to First Nations. "Should this program determine that greater than 42,500 chinook salmon are likely to return, the department will engage the Yukon Salmon Sub-Committee and Yukon First Nations to determine allocation of surplus fish to Yukon First Nation subsistence fisheries.”

The first and second pulses of the chinook migration have now passed the Pilot Station sonar, and genetic sampling shows 50 per cent of the first pulse is of Yukon origin, and 52 per cent of second pulse is of Yukon origin, according to a report out of Alaska.

Typically, the Alaskan scientist explained, the percentage of Yukon origin chinook drops off to about 30 per cent in the third and final pulse.

Schmidt said it's simply a case of Mother Nature telling the chinook of Yukon origin they have 3,000 kilometres to swim, so they'd better get an early start.

The most recent Pilot Station estimate as of midnight Monday estimates the number of chinook that have gone by at 100,371.

The largest single day count of 9,470 occurred on June 18.

This year's run is being described as at least four days early.

Schmidt said all indications from villagers, state troopers and others monitoring the chinook closure, including herself, suggest the subsistence fishermen are doing whatever they can to keep their chinook catch to zero.

There is, for instance, a prohibition on all gill nets for the commercial chum salmon fishery. The fishery must use dip nets to fish for chum, then release any chinook caught.

"They can release them pretty easy from the dip net,” Schmidt explained. "They don't even need to bring the net out of the water. They just flip it over and the fish slips out.”

So far, it's estimated 3,877 chinook have been released by Alaska's commercial chum fishery, which has harvested an estimated 152,000 chum so far.

The average annual harvest of chinook salmon on the Yukon side of the border from 1961 to 2012 was 11,146 fish, with a high of 22,846 taken in 1982.

The average harvest from 2008 to 2012 was 3,652, less than a third of the 50-year average.

Last year, the aboriginal harvest was 2,146.