Lower Deschutes Fish Update

From my perspective, one of the highlights of the Deschutes Fisheries Workshop is the annual report on lower Deschutes fish from ODFW.  That presentation did not occur this year, so I talked to Rod French, ODFW Mid-Columbia District Fish Biologist which includes the lower Deschutes.  There was a surprise, read on for more.

The annual lower Deschutes trout survey was interrupted this spring by the pandemic, but Rod is finishing up the analysis and it appears that little changed compared to recent surveys.  Redband trout growth, fitness, and abundance remain excellent. These condition factors continue to be superior to those observed prior to the operation of the Selective Water Withdrawal tower in Lake Billy Chinook.

Black Spot Disease is still prevalent but continues to have no observable negative impact on the fish. The prevalence of BSD varied by area, reaching a high of about 70% of all fish in some reaches, but often there were very few spots observed on any one fish.  Prevalence decreased as they moved down river during sampling.  Of course, temperatures increase going downstream, so there seems to be no or an inverse correlation between BSD and water temperature.

The 2019/2020 steelhead run was poor.  No surprise there for steelhead anglers.  Last season even saw a decrease in Round Butte Hatchery fish.  You can see all the numbers since the 1977-1978 season here, but last year only 1,492 wild steelhead and 1,328 Round Butte Hatchery steelhead returned to the Deschutes River.  There was a large jump in stray hatchery fish at 1,898.  If you look only at the wild and RBH fish, then this most recent season was even worse than 2018/2019.

The big surprise was an enormous increase in the wild fall chinook run. The 2019 Deschutes fall chinook run was the largest since counting began in 1977.  This is a total surprise and counters everything I thought I knew about recent chinook runs.  Chinook counts were very low in the Columbia Basin and ocean counts were low as well.  Why the Deschutes run was 5 times higher this year than in recent years is anyone’s guess.  On the other hand, only 201 wild spring chinook returned to the Warm Springs hatchery in 2019 and the 10-year average is now down to 633 fish.  Spring chinook are clearly in serious trouble.

Plato attributed this quote to Socrates: “The only true wisdom is knowing that you know nothing”.  Once again, I am reminded of just how little we know.  I’m pretty sure that does not make me wise, however.

(Note: The steelhead and fall chinook figures are estimates from annual mark and recapture studies using fish captured at the Sherar’s Falls ladder.  Redd counts for fall chinook are also made.  Annual population estimates have been made for these fish using the same techniques for many years. Clearly, they are estimates and are best used to get a general understanding of the run and to be able to compare it to prior years.)