The impact of Hungry Horse Dam on the fishery of the Flathead River : final report

Fraley, John J.; Graham, Patrick

doi:10.5962/bhl.title.101053

Cited by 14 publications

(45 citation statements)

References 10 publications

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“…We assumed that the main stem Flathead River and the Flathead lakeshore contributed a substantial portion of the total recruitment to Flathead Lake during the 1960s through mid 1970s (Fraley and Graham, 1982). Strong year classes of kokanee in Flathead Lake were produced when flow and lake level conditions were favourable.…”

Section: Methodsmentioning

confidence: 99%

“…Formerly, the Flathead River and Flathead lakeshore supported a major portion of the kokanee spawning run (Fraley and Graham, 1982;Decker-Hess and Clancey, 1984). Spawning in the Flathead River increased markedly after the completion of Hungry Horse Dam in 1953, aided by hypolimnial discharges which resulted in warmer winter water temperatures.…”

Section: Population Decline and Present Statusmentioning

confidence: 99%

“…Seasonally, operations shifted to higher flows during the fall spawning period and lower flows during the winter incubation period (Figure 2). This operational pattern led to subsequent dewatering and freezing of incubating kokanee eggs deposited during periods of higher flows (Fraley and Graham, 1982). High incubation mortality was probably the major factor in the decline of the main stem kokanee spawning run, which fell from an estimated several hundred thousand fish in the mid-seventies, to an average of 10,800 from 1979-1984.…”

Section: Population Decline and Present Statusmentioning

confidence: 99%

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Effects of stream and lake regulation on reproductive success of kokanee in the flathead river system, Montana, U.S.A

Fraley

Decker-Hess

1987

Regul. Rivers: Res. Mgmt.

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Kokanee (Oncorhynchus nerka) provided an important recreational fishery in the Flathead River-Lake system (Columbia River Basin, U.S.A.-Canada) until the late 1970s when populations declined dramatically. The declines coincided with peaking river discharge from Hungry Horse Dam during the autumn spawning period and an increase in the duration of lake drawdown caused by the operation of Kerr Dam on the outlet of Flathead Lake. Redds of both river and lakeshore spawners were, therefore, dewatered in winter, causing high freezing and desiccation mortality of eggs during the incubation period. It appeared that growth rates of kokanee were density dependent. Female kokanee from strong year classes (i.e., those produced during years of favourable water levels and flow conditions during the incubation period) were smaller than those from weak year classes when unfavourable conditions for incubation prevailed. A highly significant relationship (r2 = 0.929, p < 0.001) was demonstrated between female kokanee spawner length, river gauge heights, and lake levels during years which produced each year class. The close fit of the relationship was further validated by the strong correlation (r = 0.964) between actual kokanee lengths and predicted lengths. Other factors which could have influenced kokanee year class strength include hatchery plants of kokanee fry, harvest of kokanee by anglers, variations in the carrying capacity of Flathead Lake, and natural fluctuations in egg and fry mortality. KEY WORDS Kokanee Flathead River and Lake Montana, USA Stream and lake regulation Incubation mortality Year class strength.

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Section: Methodsmentioning

confidence: 99%

Section: Population Decline and Present Statusmentioning

confidence: 99%

Section: Population Decline and Present Statusmentioning

confidence: 99%

See 1 more Smart Citation

Effects of stream and lake regulation on reproductive success of kokanee in the flathead river system, Montana, U.S.A

Fraley

Decker-Hess

1987

Regul. Rivers: Res. Mgmt.

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“…Some fish (i.e. kokanee salmon) have been known to migrate into the tailwaters during the fall and attempt to spawn there, but the fluctuating discharge regime limits success (Fraley and Graham, 1982).…”

Section: Hungry Horse Tailwatersmentioning

confidence: 99%

Mitigating the impacts of stream and lake regulation in the flathead river catchment, Montana, USA: An ecosystem perspective

Stanford¹,

Hauer²

1992

Aquatic Conservation

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ABSTRACT1. Seventy-two per cent of the Flathead River catchment (22 241 km2) is federally designated and protected as wilderness or national park. Thus, the catchment remains one of the more pristine areas of its size in the temperate latitudes of the world.2. Discharge in the downstream reaches of the river system outside the protected areas is regulated by three dams for flood control and hydropower production. These dams have blocked natural migration of native fish from Flathead Lake (496 km') and isolated populations in sub-catchments. Temperature and erratic flow fluctuations have altered phenologies of river zoobenthos and fish, and in dam tailwaters aquatic biodiversity is drastically reduced in comparison to unregulated segments.3. Ecological problems caused by changing water quality conditions, altered land-use patterns and introductions of non-native biota are interactive with the impacts of stream and lake level regulation, thereby emphasizing the complexity of this river-lake ecosystem.4. Mitigation of the effects of regulation is compromised by differing management priorities and regulatory mandates of County, State, Tribal, and Federal agencies responsible for natural resource management within the catchment. Moreover, economic and ecological interests outside the Flathead influence the way flows are regulated within the catchment.5. The most pervasive influences of stream and lake regulation can be ameliorated by retrofitting the hypolimnial release dam with a selective depth outlet structure to allow temperature control, and by controlling changes in flow rates to create a more natural hydrograph in the tailwaters of the large dams. Allowing fish passage by construction of fish ladders is problematic because upstream passage will commingle native species that were isolated upstream by construction of the dams with non-native species that were introduced subsequently below the dams. Cascading food web interactions elicited by invasions of non-native biota may offset any advantage to native stocks gained by passage and/ or augmentation with hatchery stocks.6. Mitigation must be adaptive in the sense that unanticipated effects and interactions with other management objectives can be documented and alternative action can be implemented.7. This case history of the effects of stream and lake level regulation, and the approaches to management reviewed in this paper, should serve as a lesson in river conservation.

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“…These effects can be especially acute in reregulation reservoirs, which are designed for large fluctuations in water volume to reduce fluctuations in downstream reaches. These fluctuations can ''strand'' various life stages of fish and other aquatic species (Bauersfeld 1978;Fraley and Graham 1982;Hunter 1992;Hoffman et al 2000;Saltveit et al 2001). Stranding is defined here as the separation of fish from their primary water body (river or reservoir), leading to injury or mortality.…”

mentioning

confidence: 99%

Salmonid Fry Stranding Mortality Associated with Daily Water Level Fluctuations in Trail Bridge Reservoir, Oregon

Bell¹,

Kramer²,

Zajanc³

et al. 2008

N American J Fish Manag

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Abstract.-Little information exists on how reservoir fluctuations affect stranding risk for early life stages of salmonids. This study focuses on the effects of hydroelectric-related water level fluctuations in Trail Bridge Reservoir, Oregon, where salmonids, including the bull trout Salvelinus confluentus and spring Chinook salmon Oncorhynchus tshawytscha, which are listed under the U.S. Endangered Species Act, commonly occur. A distance-from-line sampling design was employed using permanently established transects to estimate the magnitude of stranding of juvenile salmonids during 30 surveys over 3 months in spring 2006. All stranded fish observed during field surveys were mapped onto spatially rectified, low-elevation aerial photographs to assess the patterns in stranding. Most fish were stranded in habitats with a slope of less than 6%, typically in interstitial spaces among cobbles, and in ''potholes.'' Fish were stranded in similar numbers following small or large fluctuations, and no relationship was apparent between the range in fluctuation and the number of stranded fish or between the average rate of water surface decline and the number of stranded fish. Based on extrapolation, we estimated that 808 spring Chinook salmon fry and 444 brook trout S. fontinalis fry were stranded in Trail Bridge Reservoir during spring 2006. One dead bull trout was observed, but based on the abrasions, open wounds, and signs of infection that we observed, it died prior to the decline in reservoir elevation. Our findings suggest that stranding in this reservoir could be reduced (while retaining the hydroelectric function of the reservoir) by restricting fluctuations to specific elevations during vulnerable fish migration periods, increasing the slope of areas identified as having a high stranding risk, or both.

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The impact of Hungry Horse Dam on the fishery of the Flathead River : final report

Cited by 14 publications

References 10 publications

Effects of stream and lake regulation on reproductive success of kokanee in the flathead river system, Montana, U.S.A

Effects of stream and lake regulation on reproductive success of kokanee in the flathead river system, Montana, U.S.A

Mitigating the impacts of stream and lake regulation in the flathead river catchment, Montana, USA: An ecosystem perspective

Salmonid Fry Stranding Mortality Associated with Daily Water Level Fluctuations in Trail Bridge Reservoir, Oregon

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