Thousands of fall chinook salmon are swimming up the Columbia River every day right now. This year’s migration is expected to be one of the largest in recent years. Researchers aren’t sure exactly why fall chinook have made such a big comeback.

Salmon and steelhead restoration has been a big push throughout the Northwest -- from Puget Sound to coastal streams to the Columbia-Snake River Basin -- where fall chinook were nearly extinct by the 1960s.

For years, fall chinook weren’t the salmon people wanted to study. They weren’t as economically important or as tasty as the spring salmon runs.

But fall chinook have made a big comeback recently. Last year, a record 1.3 million fall chinook made the migration. This year’s run won’t break that record, but biologists say the numbers are still high.

And no one really knows why.

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