For the third straight year, overall
hydrosystem survival – Lower Granite Dam on the lower Snake River to Bonneville
Dam on the lower Columbia River – for yearling chinook smolts during spring
2017 was below average (this year about 6 percent below average), with an
overall survival rate of 44 percent, according to a preliminary report.
And the deficit is in the lower Columbia
River, said Steve Smith of NOAA Fisheries, as he described preliminary data for
smolt survival, travel time down through the dams and the percentage of smolts
transported by barges at the Technical Management Team’s Year End Review, Dec.
12, in Portland.
TMT is made up of fisheries and
hydro/reservoir managers from state, federal and tribal agencies. Every
December the group looks back at actions taken during spring and summer in
managing Columbia and Snake river federal hydro/fish operations. Smith’s
presentation was among nine reviewed in the day-long session. Go to http://pweb.crohms.org/tmt/agendas/2017/1212_Agenda.html to see all presentations.
With spring’s higher flows and more spill,
yearling chinook were swept down river and the median amount of time it took
for the fish to complete their initial migration journey – Lower Granite to
Bonneville – was faster than in all years since 2001, although still very
similar to 2016’s travel time. In early April travel time was about 17 days,
but by May it took the fish only about 10 days to make the journey and in early
June the timing of the journey dropped to about 7 days.
Travel time during 2015’s low flows was a good
four to five days slower, Smith said.
Steelhead move much faster than chinook and
“for most of 2017 these were the fastest moving steelhead that we’ve seen,” he
said. The steelhead journey over most the study time – early April through
mid-June – was under 10 days, dropping to a low of 7 days June 4.
Reach by reach survival varied: survival of
yearling chinook from Snake and Clearwater river hatcheries to Lower Granite
Dam was 65 percent, which is near the mean of 64.8 days. Survival from upper
Columbia River hatcheries to McNary Dam was slightly above average at 58.2
percent (the mean since 1999 is 56.5 percent).
Upper Columbia River steelhead survival to
McNary Dam this year was 43.7 percent, slightly higher than the mean since 1999
of 41.9 percent.
All reaches (dam to dam) had above average
survival with the exceptions of McNary Dam to John Day Dam where survival for
yearling chinook was just 72 percent (mean survival is 87.2 percent), Little
Goose Dam to Lower Monumental Dam where survival was 90.8 percent (mean
survival is 94 percent) and Lower Granite to Little Goose where survival was
91.6 percent (mean is 93.3 percent).
Overall survival of Snake River yearling
chinook from Lower Granite to McNary in 2017 was 74.3 percent, slightly lower
than the mean of 75.5 percent.
Overall survival from McNary to Bonneville was
64.3 percent, far lower than the mean of 71.6 percent.
Survival for upper Columbia yearling chinook
was vastly different with a survival of fish from McNary to Bonneville of 94.4
percent. The mean is 82.5 percent.
Snake River steelhead survival was below the
mean at lower Columbia dams. The Dalles Dam to Bonneville survival this year
was 80.2 percent (mean survival is 89.1 percent). John Day to Bonneville
survival was 64.3 percent (mean is 80 percent). However, McNary to John Day
survival was 94.1 percent, higher than the mean of 85.7 percent.
Survival for steelhead in Snake River reaches
was higher than the mean at all four dams. Lower Granite to McNary survival was
75.9 percent, higher than the mean of 67.4 percent.
However, McNary to Bonneville survival for
steelhead was 60.5 percent, far lower than the mean of 70.8 percent.
As with yearling chinook, survival of
steelhead from the upper Columbia was much better than average. Survival this
year was 96.4 percent, whereas the mean is 74.7 percent.
The entire journey – the Snake River trap
upstream of Lower Granite Dam to Bonneville – for yearling chinook this year
was below the mean survival with 44.4 percent survival compared to the mean of
For steelhead for the same long stretch of
Snake and Columbia rivers, survival was 42.9 percent while the mean is 48.9
Survival of Springfield Hatchery Snake River
sockeye from the Redfish Lake Trap to Lower Granite Dam was a dismal 16.2
percent. The mean is 46 percent. Snake River sockeye are listed as endangered
under the federal Endangered Species Act.
For the sockeye that made it to Lower Granite,
survival was a bit better during the remainder of their journey. Lower Granite
to McNary survival was 54.4 percent, but still much lower than the mean at 66.4
percent. McNary to Bonneville survival was just 32.4 percent, while the mean
since 1997 is nearly twice as high at 61.2 percent.
Overall survival of sockeye – Lower Granite to
Bonneville – was a nearly record low of 17.6 percent. The mean since 1997 is
The number of smolts transported this year was
low, continuing a trend of fewer and fewer Snake River fish traveling by barge
to Bonneville Dam.
Just 19.7 percent of yearling chinook were
transported from one of the three dams on the Snake River that collect and
transport fish. 2016 was about the same, whereas transportation during the low
flow year of 2015 was only about 12 percent. For the years 2007 through 2017
the mean transportation percentage is 29.7. For the years 1996 through 2005,
the mean is 80.7 percent of the fish transported.
Likewise, steelhead transportation was low
this year. Some 22.1 percent of the fish were transported. A slightly higher
percentage of steelhead were transported in 2016 and 2015 was about 12 percent.
The mean – 2007 to 2017 – is 33.5 percent. The mean – 1996 to 2005 – is 87.4
--CBB, October 6, 2017, “2017 Juvenile
Salmon/Steelhead Survival In Snake/Columbia: Fish Take Hit In McNary To John
Day Reach,” http://www.cbbulletin.com/439683.aspx
--CBB, December 22, 2016, “Year-End Assessment
Matches 2016 Water Supply, Stream Flow, Fish Conditions With Juvenile
--CBB, October 7, 2016, “Report Details 2016
Juvenile Salmon/Steelhead Survival In Snake/Columbia; Snake Sockeye Take A