The Anadromous Fish Evaluation Program

Adult Salmon and Lamprey Studies

Background, Issues, Spill,

Dam Passage, Temperature

Beginning in 1990, the Corps and Bonneville Power Administration have funded research on the upstream migration of adult salmon, steelhead, and (in 1995) Pacific lamprey through the Federal Columbia River Power System (FCRPS) and into tributaries. The research focused on migration past the dams and through reservoirs on either the Snake or Columbia Rivers. Fish were tagged with radio transmitters, and their migration was monitored from 1991-1994 through the Snake River and 1996-1998 through the Columbia River. Results of the Snake River study reported migration characteristics, fishway passage parameters, and affects on passage behavior of project operations. Currently, data analysis and reporting results are being conducted for general migration and several fallback elements of the Columbia River study.

Background
Adult salmon and steelhead migrating to their natal streams in the Columbia River Basin must pass eight or nine Snake and Columbia River dams. Mortality and reduction in reproductive success due to conditions caused by the FCRPS must be minimized in order to maintain and recover native runs of fish in the basin. In a recent report on adult fish passage, the Independent Scientific Advisory Board (ISAB) stated that correction and prevention of problems with adult fish passage deserve more attention than they have received. They point out that there currently is no research program addressing the questions regarding hydrosystem-related delay and extra energy expenditure on the ability of adult fish to spawn successfully.

Substantial information exists on adult fish passage at lower Snake and Columbia River dams. From the late 1960's through the 1970's, extensive research regarding the affects of ladder slope, flows, and weir configuration on fish passage were conducted at the Corps Fisheries Engineering Research Lab. Results of these studies led to the development and modification of adult fish passage facilities on the Snake and Columbia Rivers. Field studies using a variety of techniques led to further facility design and operation refinements. Subsequent changes in the FCRPS (i.e., Bonneville Lock and Dam’s new navigation lock), advances in radio telemetry technology, and a need for more detailed information warranted additional studies on adult fish passage.

Adult salmon, steelhead, and later Pacific lamprey migrations have been studied by National Marine Fisheries Service (NMFS) and the Idaho Cooperative Fish and Wildlife Research Unit, of the United States Geological Survey (USGS) since 1991. Field work began with trial trapping of fish in the river downstream from Ice Harbor Lock and Dam (1991) and Bonneville Lock and Dam (1996) and installation of radio telemetry gear at the dams. Adult salmon, steelhead, and lamprey were captured at either Ice Habor, John Day, or Bonneville Locks and Dams. They were outfitted with radio transmitters and released downstream from the dam to better define the following: (1) the use of fishway entrances and passage through the fishways; (2) the affect of spill and powerhouse discharge patterns on the entry of fish into the fishways and on passage rates; (3) the affect of the new Bonneville navigation lock on fish passage at the dam and movement into Bonneville Hatchery; (4) the rate of fallback over the dams with various flow conditions; and (5) the distribution, migration rates, and survival of fish after they are tagged and released near Bonneville Lock and Dam.
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Issues
The FCRPS may affect adult salmon and steelhead survival and reproductive success on both project-specific and system-wide levels. Spill, dam passage, and altered temperature regimes are all elements of the FCRPS that upstream migrants encounter. Spill may affect adult salmon and steelhead in a number of ways including fallback, exposure to gas supersaturation, and by masking attraction to ladder entrances. Dam passage may delay upstream migrants. Difficulty during dam passage may use up more of the adult migrants’ limited energy reserves than passage through a normative river. Exposure to prolonged, elevated temperatures may cause fish to stray and delay, increase their susceptibility to disease, and increase consumption of their energy reserves.
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Spill
Salmon and steelhead fallback at Columbia and Snake River projects is well documented (Bjornn and Peery 1992, Dauble and Mueller 1993). Fallback was first suspected as a likely cause of mortality at Bonneville Lock and Dam in 1943. Merrell and Collins (1960) found a relationship between spill level and mortality for large numbers of dead fish observed in 1943, 1950, 1952, and from 1954 through 1956. Recent radio telemetry information collected by USGS/NMFS indicates that survival for fish that fall back is approximately 5 percent less than for fish that do not fall back. The recent radio telemetry data also suggests fallback rates are related to spill level at Bonneville Lock and Dam; however spill level explained only a portion of the fish that fell back. For 1996-98 chinook salmon data, linear regression of spill level versus fallback ratio produced R-squared values ranging from 0.23 to 0.47. As an example, the 1998 linear regression model estimates a 5-percent increase in fallback rate for a 100,000 cubic feet per second (cfs) increase in spill over the cap. In addition, fallback rates of fish that fell back within 24 hours of passing Bonneville Lock and Dam were roughly half of the overall fallback rates observed during 1996-98 radio telemetry studies. Also, some fish traveled upstream several kilometers before turning around and falling back over the dam. Why fish fall back, the importance of spill to fallback, and the affect fallback has on adult salmon reproductive success are questions that need more detailed answers.

Death can occur if fish are exposed to total dissolved gas (TDG) saturation exceeding 120 percent (Chapman et al. 1991); however, limited exposure duration and the ability to sound to escape high saturation levels are factors that reduce mortality. Documented incidents of mortality due to TDG supersaturation have occurred. Junge and Carnegie (1976) used counts to study the affects of unregulated spill compared to a crowned spill pattern and found “losses” of 33 to 44 percent under unregulated spill and 13 percent during the crowned spill pattern. Gray and Haynes (1977) found that adult chinook salmon traveled deeper during times of TDG supersaturation, but there is little information regarding adult fish avoidance and exposure to gas supersaturation in the FCRPS.

The efficiency of adjusting spill schedules to improve adult fish passage has been well demonstrated (Junge 1967, 1972). From the late 1960’s to present, spill patterns that maximize adult attraction to ladder entrances have been developed and fine-tuned for Corps projects. Conflicts with using spill for juvenile passage and managing dissolved gas require established patterns to be changed. For example, current juvenile fish survival studies planned for The Dalles Lock and Dam investigate using the juvenile spill pattern during the daytime to see if juvenile fish survival rates increase. Also, the fast-track gas program may call for changing established adult fish spill patterns or increasing daytime spill. The affect of these changes on adult fish passage times, entrance use, and fallback rates will require further study before long-term implementation can be considered.
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Dam Passage
Past and recent radio telemetry studies demonstrate that adult migrants are delayed at dams. Project passage times can range from 1 to 1,174 hours (Stansell in-prep). Compilation of past telemetry data show median project passage times ranging from 30 to 60 hours for Bonneville, The Dalles, and John Day Locks and Dams (Stansell in-prep). The most recent radio telemetry data show dam passage times to be less than 24 hours, passage through reservoirs to be less than through free-flowing rivers, and passage through the system to be equal to or less than through the Snake River if it was free-flowing. Past and recent studies point to the time to first entrance and transition pools as the primary culprits of delay at projects.

Information on the relationship between dam passage and energy expenditure is limited. Conner et al. (1964) looked at changes in glycogen and lactate levels of salmonids as they ascended experimental “endless” fishways and found the degree of exercise to be moderate, even during prolonged ascents. How energy expenditure at dams compares to that of the normative river and how it relates to spawning success is unknown.
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Temperature
The recent ISAB report on adult fish passage states, “Upstream migrants, particularly Snake River summer and fall chinook and summer steelhead, experience warmer temperatures for a longer duration during migration than they experienced prior to construction of the major upstream water storage projects.” In 1997, temperatures exceeded 20 degrees (º) Centigrade (C) on 67 days in John Day Lock and Dam’s south fish ladder (Dalen et al. 1998). Temperature monitoring in the Snake River has been conducted in the Ice Harbor and Lower Granite adult fish ladders between 1995 and 1998 to determine if the water temperature increased as it passed down the adult fish ladders. Preliminary data (Bjornn, in prep) from this monitoring indicates that ladder temperature exceeds 21 ºC for short durations in hot, dry years, and during these periods, a temperature gradient (>2 ºC) may form within the ladder. In addition to the infrequent occurrence of a temperature gradient in the adult ladder, adult passage timing and behavior, through the ladder during this condition, does not appear to be affected (Bjornn, FFDRWG presentation, 1999).

Temperatures in Portland District fish ladders have been extensively monitored (Dalen et al. 1996, 1997, and 1998). The ISAB points out that adult chinook salmon held above 15.6 ºC at hatcheries have a lowered reproductive potential. Bell (1991) states that the upper limit of the optimum migration temperature range for chinook is 14 ºC. Bell (1991) also says that fish can detect temperature differences as small as 0.28 ºC. How adult fish react to these high temperatures and small temperature differences is not well understood. It is well known, however, that many adult salmonids migrating through the lower Columbia River dip into the cooler tributary mouths along their way upstream. The USGS/NMFS data show that few chinook salmon stray temporarily into tributaries, but that large numbers of steelhead destined for the Snake River enter lower Columbia River tributaries temporarily. There is little information on the existence of cool-water areas and their use as thermal refuges by adult salmonids migrating through the lower Snake and Columbia Rivers.

Straying in adult salmon species is attributed to the natural plasticity in the species’ behavior to utilize resources available during periods of poor river conditions (high temperature, low flows, or lack of spawning habitat). Our ability to discern the natural straying behavior from behavior caused in reaction to hydroproject operation (such as reduced flows, transportation, and altered temperature regimes) is at best difficult. Questions about the affects of transportation on the straying and delay of adult fish during their upstream migration have not been fully answered. It was not until the recent development of Passive Integrated Transponder (PIT)-Tag technology and the increased regional PIT tagging of juvenile fish that this type of study became feasible. Thus, to understand the potential affects of the route of juvenile salmon outmigration (transport versus in-river passage) on the homing abilities as adult fish, a pilot study was initiated in 1997 and 1998 with the collection and subsequent radio tracking of spring and summer chinook salmon recovered from the Lower Granite Lock and Dam adult fish trap. Although adult fish returns were limited, the results of the pilot study indicate that there is a differential rate of homing efficiencies for transported compared to in-river outmigrants and for hatchery and wild fish. The recent increase in straying of steehead originating from the Snake River into the Deschutes River has re-emphasized the need to understand the factors that influence homing success. Future work is proposed to further understand the affects of transportation on the straying and homing of steelhead (and fall chinook salmon) and the implications on the successful and productive spawning in their stream of origin or hatchery.
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ADULT SALMON AND LAMPREY STUDIES, REFERENCES

For further information on this event:
Rebecca Kalamasz, 509-527-7277

Topics
[Bypass System ] [In-River Passage] [Surface Collection]
[Feasibility Studies-Walla Walla District] [Feasibility Studies-Portland District] [Transportation] [Turbine Survival ]

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U.S. Army Corps of Engineers, Walla Walla District
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