Latest CSS Results Show
by Bill Rudolph
Hatchery sockeye from Sawtooth showed a 61-percent benefit from migrating inriver,
those from Oxbow a 14-percent improvement over transported stocks.
The latest analysis from the Fish Passage Center's Comparative Survival Study shows that despite the second highest survival (60 percent) of juvenile spring Chinook migrating inriver from the Snake River in 2012, barging still improved the survival to adulthood of some stocks.
But the report said inriver migrating wild spring Chinook had an overall 31 percent better smolt-to-adult rate [SAR] than barged springers in 2012, similar to results from the 2011 outmigration. In 2010, the barged fish had a 21-percent advantage.
Overall, the CSS analysis said the 1994-2012 geometric mean of wild springer SARs from the Snake gave a 15-percent survival edge to the barged fish. And since 2006, when spring spill was increased by court order, presumably to produce more adult returns, the barged fish still showed survival benefits over inriver migrators in four out of seven years, ranging from 11 percent to 27 percent.
In 2012, the SARs of some hatchery stocks from the Snake beat their inriver components, including those from the Clearwater Hatchery (16 percent better), the Sawtooth Hatchery (93 percent better), McCall Hatchery (16 percent better), and the Imnaha Hatchery (20 percent better).
The inriver component from Dworshak Hatchery spring Chinook did only 2 percent better than the barged fish, while the Rapid River facility's inriver migrators did 3 percent better. Inriver fish from Catherine Creek did 34 percent better, and Clearwater summer Chinook showed a 17-percent benefit from staying inriver in 2012.
Snake River steelhead results were complete for the 2011 outmigration, and barged wild steelhead SARs showed an 18-percent benefit. Hatchery steelhead showed an 11-percent benefit, with the complete B-run SARs showing a 2-percent benefit for inriver migrators.
Hatchery sockeye from Sawtooth showed a 61-percent benefit from migrating inriver, those from Oxbow a 14-percent improvement over transported stocks.
With an unusual water year in 2012, which found peak flows occurring in late April rather than May, many fish had passed Snake collector dams before the fish transportation program even began. Nearly 70 percent of the juvenile spring Chinook and 60 percent of the young steelhead had passed the project before barging started.
Preliminary estimates found only 23 percent of wild spring Chinook being transported that spring, along with about 25 percent of hatchery spring chinook. For wild steelhead, it was estimated that about 28 percent were barged, along with 27 percent of hatchery-origin steelies.
High spill levels, along with surface bypass collectors, kept numbers of fish entering bypass systems low compared to other passage routes. But during May, about 60 percent of the smolts that passed Lower Granite ended up being barged from there or a collector dam downstream.
According to the 2014 CSS, "The overall SARs for Upper Columbia and Snake river populations of salmon and steelhead are not meeting the 2 percent to 6 percent regional goal, while middle Columbia populations are meeting the regional SAR goals in most years." But the report acknowledges its results may be lowballing SARs in a big way. The Idaho Department of Fish and Game calculated SARs more than 40 percent higher, according to run reconstruction analysis of returns from 1996-2011.
The CSS study reported that the overall SAR for wild Snake River spring Chinook was .95 percent, about three times the SAR from the 2011 outmigration, and the highest since 2009.
The wild Snake steelhead SAR for the 2011 outmigration (latest data) showed a 1.26 percent SAR, with a .64 percent SAR for the hatchery component.
For the 2012 Snake hatchery sockeye migration, the fish from Oxbow had an estimated 2.26 percent SAR, compared to 2011's .39 percent, while fish from the Sawtooth facility saw only a .11 percent return rate.
SARs (JD-Bonn) for wild spring Chinook in the John Day River rebounded from the 2011 outmigration's .9 percent SAR (McNary-McNary), to 3.15 percent, and wild Yakima spring Chinook SARs got a significant bump as well, to 2.68 percent from 2011's .73 percent.
The spring Chinook from Carson Hatchery exhibited a .63 percent SAR (Bonn-Bonn) from the 2012 outmigration, up from 2011's .46 percent, while the hatchery springers from the Cle Elum facility showed a bump up to 1.13 percent from .87 percent in 2011.
For stocks in the upper Columbia, wild springers in the Wenatchee River showed a .87 percent return rate from the 2012 outmigration, slightly lower than 2011's .95 percent. Wild springers from the Entiat and Methow had a 1.08-percent SAR, up significantly from .41 percent the year before.
The CSS analysis of fall Chinook showed that any benefits from barging varied from year to year. The report said "there appeared to be a significant benefit for some transport groups in 2008, while in 2009, the pattern of little or no transport benefit appears similar to 2006. With 2-salt and 3-salt returns available for 2010 there appears to be no transport benefit for that year as well, although those returns are not complete. Migration year 2011 showed the least transport benefit."
"These results indicate that the smolt transportation program for juvenile fall Chinook salmon does not adequately mitigate for the adverse effects of development and operation of the Snake and Columbia rivers hydropower projects on fall Chinook survival and adult return," said the CSS report. But at a recent research forum sponsored by the U.S. Army Corps of Engineers, federal scientists said that barging fall Chinook was beneficial after June 15. That date is about the halfway point in the juvenile fall Chinook run at Lower Granite Dam.
At that December 2014 forum, NOAA Fisheries scientists reported that for the 2012 migration year, the transportation strategy, which began around May 1, also showed modest benefits for wild and hatchery spring Chinook, and wild and hatchery steelhead.
The feds' analysis tracked SARs on a daily basis, and estimated that in 2012, wild spring Chinook SARs of inriver migrators were nearly 2 percent in early April, but had declined to slightly above 1 percent when the transportation program began. Throughout May, SARs of barged fish were higher, but overall SARs of both groups had declined to about .5 percent by the end of the migration.
Sockeye Snafu Spoils 2010 Barging Study by Bill Rudolph, NW Fishletter, 3/29/11
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