NOAA Fisheries released earlier this month four draft "Technical Memoranda" or "white papers" that summarize the science to be used in rewriting its 2000 Biological Opinion of the Federal Columbia River Power System, including three that describe what scientists know about the impacts of the hydroelectric system on salmon recovery.
The fisheries agency had released the preliminary drafts of the white papers -- three for the hydroelectric system and one for habitat -- in January 2004, but the hydro papers at that time had few conclusions. NOAA Science Center scientists have now added those conclusions and put the white papers out for review.
In addition, information contained in the papers is currently being used in the collaborative BiOp remand discussions with states, other federal agencies and tribes. Nearly one year ago, June 2, 2003, U.S. District Court Judge James Redden gave NOAA one year to correct deficiencies in the biological opinion that he had cited in his May ruling that declared the BiOp invalid. Redden has subsequently allowed an extension for the work to be completed by Nov. 30, 2004. The white papers, representing some of the latest research, inform this remand process.
The three hydro white papers are:
All three drafts can be found at: www.salmonrecovery.gov/R_Analysis.shtml
- "Effects of the Federal Columbia River Power System on Salmon Populations" by John G. Williams, Steven G. Smith, William D. Muir, Benjamin P. Sandford, Stephen Achord, Regan McNatt, Douglas M. Marsh, Richard W. Zabel, and Mark D. Scheuerell;
- "Passage of Juvenile and Adult Salmonids Past Columbia and Snake River Dams" by John W. Ferguson, R. Lynn McComas, Randall F. Absolon, Dean A. Brege, Michael H. Gessel, Lyle G. Gilbreath, Bruce H. Monk, and Gene M. Matthews;
- "The Role of the Estuary in the Recovery of Columbia Basin Salmon" by Kurt L. Fresh, Edmundo Casillas, Lyndal Johnson, and Daniel L. Bottom;
Among the conclusions scientists reached for each of the hydro white papers are:
- "Effects of the Federal Columbia River Power System on Salmon Populations"
- At this point, precise survival estimates through the power system for juveniles is possible and biologists are improving knowledge about upstream migrants and for some Evolutionary Significant Units (ESU) there is a general sense of the relative survival of transported fish compared with in-river fish. While there is limited information about latent mortality, "we believe a major component of latent mortality is the disruption of timing of transported fish and in-river migrants," the white paper said.
- Substantial improvements in survival through the hydrosystem are unlikely. Technological fixes at dams may be facing diminishing returns in survival improvement. Reducing reservoir mortality, understanding how to reduce latent mortality, improving estuary habitat and spawning habitat will now get the best results.
- Additional research is needed on 1) migrational timing and its affect on smolt to adult return rate (SAR) for transport and in-river fish; 2) selectivity of bypass systems; 3) mechanisms leading toward latent mortality.
- Adult return rate is impacted by several factors, among which is survival through the hydro system and ocean conditions. It is clear ocean conditions are the dominating factor.
- Transportation is not a panacea. In many cases, transportation results in little benefit, nor harm. However, in low flow conditions during certain times of the year, transportation is beneficial. The benefits of transportation decline the closer the collection site to Bonneville Dam. Strategies such as "spread the risk" indicate more fish should be allowed to remain in-river when possible.
- Although there appears to be little relationship between flow and survival of spring migrants in the Snake River, flow does affect timing and arrival timing in the estuary affects SAR.
- "Passage of Juvenile and Adult Salmonids Past Columbia and Snake River Dams"
- Consequences of spill are increased fish passage efficiency and reduced delays in migration.
- Spill efficiency, the amount of river that should be spilled and when, varies by dam. In general, although not in all cases (Ice Harbor and The Dalles dams are exceptions), spill efficiency increases with the amount of river spilled.
- Spill can reduce predation, as well as high water temperature and disease.
- Under certain conditions -- i.e. low flow -- spill survival at dams with flow deflectors is lower than dams without flow deflectors.
- The time juveniles spend in the tailrace is influenced by the amount and pattern of spill, but generally spillway passage provides better egress from the tailrace than does passage through the bypass system.
- Conclusions about summer spill are still being developed.
- "The Role of the Estuary in the Recovery of Columbia Basin Salmon"
- Scientists' understanding of the role that the estuary (from Bonneville Dam to the Columbia River plume) plays in the salmon life cycle has changed from one that considered the estuary a bottleneck for salmon to one that considers the estuary a part of the salmon lifecycle.
- The estuary contributes to "the viability of salmon populations by contributing to the range of places salmon can use (spatial structure), providing support for the life history strategies to use these places (diversity), and providing habitat capacity to produce successful recruits (abundance and productivity)," the white paper said. Spatial structure and diversity are especially important.
- "Flow is a fundamental factor affecting characteristics of salmon and their habitat in the estuary and plume," the white paper said. Hydro operations have had a significant impact on flow in the estuary, including a reduction in the mean annual flow, reduced spring freshets, "an almost complete loss of overbank flows," and changes in timing. This has affected habitat, including loss of vegetation and shallow water habitat. There has been a loss of emergent marsh, tidal swamp and forested wetlands.
- Predation in the estuary is a major source of mortality. Management of Caspian terns could improve productivity for some salmon populations that are in the estuary while terns are nesting.
- For stream type ESUs, such as upper Columbia River chinook salmon and Snake River steelhead juveniles, survival is most affected by flow and predation. Stream type ESUs spend as much as a year rearing in freshwater.
- For ocean type ESUs, such as Lower Columbia River chum salmon and Snake River fall chinook, survival in the estuary is most affected by flow and habitat. Ocean type ESUs soon travel to the ocean after emergence from the gravel.
NOAA Releases Hydro White Paper Drafts with Conclusions
Columbia Basin Bulletin, May 21, 2004
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