Flow theorists had another fact on their side that Northwest fishermen have always known: after heavy rains, salmon begin to move upriver. Observers at dams counting returning salmon eventually detected another phenomenon: three or four years after a particularly wet spring, more adult salmon would return. Some salmon biologists began to focus on the relationship between river flow and salmon populations.
In the late 1970s, biologists at the National Marine Fisheries Service began for the first time to estimate the survival of juvenile salmon migrating downstream in the Columbia and Snake Rivers. There were two seminal papers. The first, by Howard Raymond, used mark/recapture techniques to estimate survival for groups of juvenile chinook salmon and steelhead.25 Later, Carl Sims and Frank Ossiander constructed a flow/survival relationship using that data.26
The flow/survival relationship was ultimately based on what NMFS scientist John Williams has somewhat derisively termed the "seven points of light": seven flow/survival years from which the researchers drew a graph of the supposed relationship between river flow and the survival of juvenile salmon.
Figure 2: Early Correlations of Flow and Survival27
One can see why the original researchers might be tempted to draw a line to fit these points, deriving a rough and ready relationship between flow and survival. The flow theorists, however, went much farther. They declared that if the dam operators would simply release water from upstream reservoirs, the survival of salmon would improve, in amounts to be predicted by using the same mathematical relationship.
When NMFS scientists returned to re-examine the original data used by Raymond, Sims and Ossiander, they found an extraordinary plasticity in survival estimates based on these techniques, and that if proper techniques were applied, the early estimates of survival were perhaps a factor of two too low.28 Another researcher who studied the original data even more closely found the studies riddled with questionable assumptions, and pointed out that by comparing the original data on treatment and control group recovery rates, survival exceeded 100% on 8 out of 22 occasions for fish traveling from the lower Snake River to Ice Harbor Dam29 Per project survival estimates were even skewed by a failure to count the number of dams correctly.
These scientists advised that conditions at the dams were far different during the 1970s, something the Corps of Engineers had long tried to point out. In particular, the two low flow/low survival years that provided most of the slope to the flow survival curve1973 and 1977were years when poorly designed fish passage facilities (since improved) clogged with trash and descaled and ultimately killed the fish.30 The NMFS scientists concluded that the Sims and Ossiander (1981) flow/survival relationship developed from studies in the 1970s does not predict the current survival of spring-migrating juvenile chinook salmon, particularly those migrating under low flow conditions.31
The independent reviewer concurred: Fisheries managers, the public, and the fish themselves would be better served by data collected under present conditions using current technological and analytical techniques.32 He was certainly right about the public and the fish themselves. Fishery managers eager to extract money from the hydropower system, however, continue to use the older data to this day.
Another major problem with most of the papers cited by flow theorists was the failure to account for spill at hydroelectric projects which, can, at moderate levels, improve salmon survival. For example, flow proponents and harvest agencies often cite a 1993 draft paper by Ray Hilborn in support of their claims that flow affects survival.33 They fail to disclose that the draft was withdrawn for revision in light of criticism that it did not examine spill, prevailing water temperature, degree of transportation . . . and may not have used suitable controls.34 As far as I know, a revised paper was never issued, but they continue to cite the defective draft. The same problems apply to the 1992 work of Idaho Fish and Game biologist Charles Petrosky, whose oft-cited work ignored both spill and increasing numbers of turbines over the period of his study.35
The best fisheries scientists, including members of the Snake River Salmon Recovery Team appointed by the National Marine Fisheries Service to recommend a recovery plan for Snake River salmon, acknowledge that there is no direct evidence that increasing flows in the spring increases reservoir or dam passage survivals for spring chinook.36
25 H. Raymond, Effects of Dams and Impoundments on migrations of juvenile chinook salmon and steelhead from the Snake River, 1966 to 1975. Trans. Am. Fish. Soc. 108:505-29 (1979).
26 C. Sims & F. Ossiander, Migrations of juvenile chinook and steelhead trout in the Snake River from 1973 to 1979, a research summary. Final Report to U.S. Army Corps of Engineers (NMFS N.W. Fish. Sci. Cent. 1981).
27 Data from C. Steward, Assessment of the Flow-Survival Relationship Obtained by Sims & Ossiander (1981) for Snake River Spring/Summer Chinook Salmon Smolts, Final Report, BPA Contract No. DE-AM79-93BP99654, at 5 (April 1994) (reprinting Sims & Ossianders 1981 data).
28 J. Williams & G. Matthews, A review of flow/survival relationships for juvenile salmonids in the Columbia River Basin, manuscript submitted to Fishery Bulletin (NMFS CZESD March 1994), at 12.
29 C. Steward, Assessment of the Flow-Survival Relationship Obtained by Sims & Ossiander (1981) for Snake River Spring/Summer Chinook Salmon Smolts, Final Report, BPA Contract No. DE-AM79-93BP99654, at iv (April 1994)
30 J. Williams & G. Matthews, A review of flow/survival relationships for juvenile salmonids in the Columbia River Basin, manuscript submitted to Fishery Bulletin (NMFS CZESD March 1994), at 20.
31 Id. at 24.
32 C. Steward, Assessment of the Flow-Survival Relationship Obtained by Sims & Ossiander (1981) for Snake River Spring/Summer Chinook Salmon Smolts, Final Report, BPA Contract No. DE-AM79-93BP99654, at vii (April 1994)
33 R. Hilborn et al., The Relationship Between River Flow and Survival for Columbia River Chinook Salmon, U. Wash. Draft Report WH-10 (1993).
34 D. Chapman & A. Giorgi, Comments on Work of Biological and FCPRS Alternative Work Groups, at 10 n.8 (1994).
35 D. Chapman & A. Giorgi, Comments on National Marine Fisheries Service Draft Biological Opinion on FCRPS Operations, at 7 (1995).
36 Letter, Snake River Salmon Recovery Team to J. Etchart, April 17, 1997, at 7-8; see also D. Chapman & A. Giorgi, Comments on Work of Biological and FCPRS Alternative Work Groups, at 9 (1994) ( Preliminary data from the 1993 smolt migration show no relationship between detection rate [presumed to be a surrogate for survival] and either travel time or Snake River discharge . . .).
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