[4] Barges Still Beat River For Moving Steelhead
This year's annual research review sponsored by the Corps of Engineers came up with few surprises, but added support for more fish barging on the Snake River, a position that has the feds' policy at odds with a federal judge and environmental groups.
The latest information on barging fish from the Snake River presented by NOAA Fisheries scientists at the Dec. 3-6 Walla Walla gathering backs up earlier data used to justify the transportation policy incorporated in the 2008 BiOp. The latest data--from the 2006 outmigration, when the court-ordered spill operation was fully in place--show that barged steelhead returned at nearly three times the rate of inriver migrating juveniles.
A 2005 court order from U.S. District Judge James Redden called for more spill at lower Snake dams than the feds wanted. The feds say the best science shows that cutting spill for two weeks in May to get more fish in barges would benefit spring chinook and steelhead more than letting them migrate inriver during that period.
Last week, the NMFS scientists reported that the barged component of the 2006 steelhead run returned at a 1.46-percent rate, while the non-detected group--fish that went past Snake dams and McNary via spillway or turbines--only showed a 0.57-percent smolt-to-adult return (SAR) rate.
The researchers, led by NOAA Fisheries biologist Doug Marsh, found that SAR rates started high when they began PIT-tagging juveniles in late April, but fell over the next month, then rose again in the third week of May.
They reported that SARs actually hit zero for several days in the middle of the migration when barged SARs were above 2 percent.
However, the 2006 results showed no significant benefit to wild spring chinook from barging--wild inriver SARs were 0.84 percent, while barged SARs averaged 0.73 percent.
Another survival study piggybacked onto the transportation analysis that looked at the potential value of releasing barged fish further downriver below Bonneville than current operations call for (all the way to Astoria), also showed mixed results--no benefit for spring chinook but about a 30-percent boost in steelhead survival for the fish released near Astoria.
Researchers reported they are still having a hard time getting data on Snake fall chinook, which have a complicated lifestyle. Some migrate late in the year, while others hold back in reservoirs until the following spring. For September/October transported groups, their SAR rate was relatively high, 1.89 percent, but fish tagged in the summer and barged showed a SAR of only 0.14 percent (5-fish sample).
The court-ordered spill at federal dams may have played a role in increasing the number of juvenile fish that swam all the way to the ocean. NOAA scientist Bill Muir reported that the 2009's cool water, high flows and spill all helped spring chinook achieve a 53-percent survival rate through the hydrosystem this year, while steelhead set a record, nearly 70 percent.
"High spill rates, coupled with surface passage structures at all four Snake dams in 2009, early arrival of steelhead compared to past years, and a delayed start to transportation resulted in a greater number of non-PIT-tagged smolts in the Snake River than in earlier years," read the abstract of Muir's study. "As a result, fewer PIT-tagged steelhead were eaten near the confluence of the Snake and Columbia rivers by piscivorous birds, resulting in increased estimated survival through the Snake River."
Muir and fellow NOAA scientist Robert Emmett have also been tracking the arrival time of forage fish (food for young salmon) in the ocean off the Columbia River, hoping that some day fish managers may be able to better time ocean entry of juvenile fish and improve their survival.
Using two bottom-mounted echo sounders off the river mouth, they were able to track forage fish and meso-plankton populations. So far, they have found abundance levels rose by mid-May in the past two years, which they hope to correlate with higher salmonid survivals.
They said preliminary estimates point to "exceptionally" high salmon survival in 2008 and early 2009, which was probably good for young spring chinook migrating to and away from the Washington/Oregon coast. But they cautioned that later migrators like fall chinook and coho "probably had poor survival because of high Humboldt squid predation."
Canadian researchers reported continuing acoustic tag work to track spring chinook from the Snake River all the way to Vancouver Island. They said 2009 results comported with previous results from 2006 and 2008 showed no difference in survival from spring chinook from the Snake and Yakima rivers. Fish from the Yakima cross four fewer federal dams in their migratory route. The scientists say their results are inconsistent with the theory of delayed mortality--i.e. higher mortality for the Snake spring chinook because they pass more dams.
They also found little difference in the overall survival of barged and inriver migrators. Inriver fish survived at a higher rate between Bonneville and Astoria, but by the time the fish were detected 560 kilometers away at Lippy Point, off Vancouver Island, survival slightly favored the barged component.
Their take-home message was that marine survival appears to be lower than in the hydrosystem or estuary, "therefore, the role of the ocean needs to be considered when formulating conservation plans."
The Canadians tagged slightly smaller fish in 2008 and 2009, but the size of their acoustic tags makes it necessary for them to use larger fish than the Corps of Engineers studies, which use a completely different and smaller tag, allowing researchers to even track subyearlings, though their work is limited to tracking fish in the river.
Working with scientists from the Pacific Northwest National Lab, the 2009 Corps-sponsored work focused on the lower 50 kilometers of the estuary.
They reported that most of the spring chinook in their study made the 253-kilometer swim from Bonneville to Astoria in about three days, with 90-percent survival for about the first 200 kilometers, but only 84 percent made it to Astoria (22 km to river mouth) and 76 percent to East Sand Island, just 8 kilometers from the river mouth.
The researchers said subyearling fall chinook survival was relatively poor in 2009, with only 67 percent surviving from Bonneville Dam to East Sand Island, and steelhead fared even worse, with only about 53 percent making it from the last dam to the island at river kilometer 8. -B. R.
The following links were mentioned in this story:
Anadromous Fish Evaluation Program
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