2022-2023 Deschutes River steelhead return puzzle

We all know that 2021-2022 returns were disastrously low for wild steelhead in the Deschutes and most of the Pacific Northwest.  ODFW estimates that only 523 wild steelhead made it above Sherars Falls, compared to 1,935 the year before.  The current 2022-2023 Deschutes steelhead return year still has a few months to go but surprising data is emerging.  Wild steelhead counts have improved but are still low, barely above the threshold for survivability as established by ODFW.  Upper basin origin reintroduced steelhead, however, are likely to have their best return year ever.  With a few months to go, returns this year are already almost 3 times last year.

Deschutes summer steelhead generally start entering the river in June and continue to move up as far as they can to spawn until as late as the following May.  Steelhead typically start arriving at the base of the Pelton Round Butte dam complex, a little over 100 miles from the where the Deschutes meets the Columbia, as early as September, approximately 5 months after the first fish enter the river.  The peak of the return to the Pelton Trap is typically December through February. 

As of the end of January, 122 upper basin origin steelhead have been captured in the Pelton Fish Trap at the base of the Pelton Round Butte dam complex near Madras.  These are fish that were released as juveniles into a river or stream in the Upper Deschutes Basin above Lake Billy Chinook, who migrated out as smolts through Portland General Electric’s Selective Water Withdrawal Tower, and then returned as adults. 

In contrast, the 2021-2022 year saw only 46 upper basin origin adults return.  There’s a good chance that by the end of this steelhead season the previous record of 132 adult returns from 2012-2013 will be surpassed.  Regardless, this is already the best year ever in terms of adults being released back into Lake Billy Chinook where they will hopefully travel upstream and spawn.  In 2012-2013 only about half of the adults were passed into LBC, the rest were used as brood stock at Round Butte Hatchery.

It’s a mystery why upper basin origin returns are higher than anticipated this year. For comparison, only 14 true wild fish have been caught in the trap this season as of the end of January.  (Wild fish are released back into the river.) Were upper basin origin smolt numbers dramatically higher than wild two years ago? Do hatchery fish behave differently than wild fish in the Lower Deschutes River, Columbia River, and in the ocean? That’s above my pay grade ($0) to figure out, but I am curious.