Lower Deschutes fish populations & health

At last week’s fisheries workshop, ODFW gave their annual report of fisheries  population and health for the lower Deschutes.  Since the 1970s they have been electrofishing the same stretches from Warm Springs to Jones Creek.  As reported in past years, trout continue to be in excellent health.  Condition factors were good before operation of the SWW and they are at least as good now.  If anything, the fish appear to be growing faster and are larger.

ODFW also did another creel survey from Mecca Flat to below Maupin.  The overall catch rate remains excellent and is better than pre-SWW overall.  The lower Deschutes has the highest catch rate in the entire Deschutes Basin with the exception of the Crooked River.  It is also better than many out of state “blue ribbon” rivers.  (1)

This year ODFW checked trout for evidence of Black Spot Disease.   They estimate that about 50% of the trout had some level of infection.  In some cases it was barely identifiable and may not have been BSD, so the infection rate is only a rough estimate.  They remain unconcerned about BSD.  BSD has been present in the Basin for a long time and there appears to be no negative impact on trout.  Condition factors of fish with BSD were no different from non-BSD fish.  They compared BSD to getting a small cut and having a black scar form around it on your skin.

ODFW continued to monitor bass populations.  They have records going back to the 1970s of periodically finding bass in the lower Deschutes.  At last year’s workshop they reported capturing 50 bass in the summer of 2016.  This past year they found 295 bass.  Some were as high in the river as Ferry Canyon (river mile 26), but most were in the lower 12 miles.  (2)

This year they PIT tagged captured bass to track their movements.  Bass enter the lower river from the Columbia in the spring and leave in August and September.  There is no evidence of bass reproduction in the Deschutes.

The presentation also included charts of returning anadromous adults in the Deschutes.  Wild steelhead returns were low, but not as low as 1993 and 1995.  There is a lot of variability in the return numbers with no clear trend although climate change leading to drought and poor ocean conditions is thought to be the cause of recent low returns.   Stray hatchery steelhead (“B-run”) counts are way down, which is to be expected with the cessation of barging upper Columbia Basin smolts around the Columbia Dams.  Round Butte Hatchery steelhead returns continue to be higher than wild fish which also makes sense given the huge numbers that are planted into the system.  Wild fall and spring chinook were also low in 2017, but not the lowest recorded.

(1) The creel surveys continue to show good catch rates in spite of strong evidence of deliberate under reporting by some anglers.  Surveyors get questions like “which side are you on”?  There have also been message board postings asking for under reporting in an attempt to negatively influence the results.

(2) These numbers are only a sample, not a complete survey, but the numbers of bass are a fraction of the trout sampled.  It is also important to keep in mind that the Columbia River has seen a huge population growth in bass.  So much so that regulations have been changed to allow unlimited harvest of bass in the Columbia.