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Out-Migration Survival of Wild Chinook Salmon (Oncorhynchus tshawytscha) Smolts from Mill Creek through the Sacramento River during Drought Conditions.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Out-Migration Survival of Wild Chinook Salmon (Oncorhynchus tshawytscha) Smolts from Mill Creek through the Sacramento River during Drought Conditions./
Author:	Notch, Jeremy.
Description:	1 online resource (87 pages)
Notes:	Source: Masters Abstracts International, Volume: 56-06.
Subject:	Biological oceanography. -
Online resource:	click for full text (PQDT)
ISBN:	9780355131680

Out-Migration Survival of Wild Chinook Salmon (Oncorhynchus tshawytscha) Smolts from Mill Creek through the Sacramento River during Drought Conditions.
Notch, Jeremy.

Out-Migration Survival of Wild Chinook Salmon (Oncorhynchus tshawytscha) Smolts from Mill Creek through the Sacramento River during Drought Conditions. - 1 online resource (87 pages)

Source: Masters Abstracts International, Volume: 56-06.

Thesis (M.S.)--University of California, Santa Cruz, 2017.

Includes bibliographical references

Once emerged from the gravel after being spawned in natal streams, Chinook salmon spend many months rearing and growing in freshwater before undergoing smoltification and out-migrating to the ocean. This relatively short period of time is considered to be the most vulnerable and dangerous phase in the life cycle of a Pacific salmon. It is during this phase when smolts navigate around many anthropogenic structures and experience environmental stressors while making their way to the ocean. In California's Central Valley, the few remaining wild populations of Chinook salmon (Oncorhynchus tshawytscha) out-migrate through a highly modified riverine and estuary landscape characterized by leveed banks, altered flow and temperature regimes, transformed food webs, and limited floodplain and rearing habitat. Juvenile salmon smolts migrate through these landscapes within a relatively short period of time, requiring them to quickly adapt to changing water conditions and habitat types. Understanding the survival rates of wild smolts from source tributaries to the Pacific Ocean is essential in protecting and restoring these populations from the low abundances currently observed. When faced with drought conditions out-migrating smolts experience low flows, elevated water temperatures and high densities of predators while out-migrating to sea. In order to assess smolt survival during drought conditions in late spring (April-May), 304 wild smolts were acoustically tagged and tracked from Mill Creek (Tehama County) to the Pacific Ocean between 2013 and 2016. Total outmigration survival to the ocean was 0.3% during these years, with only one fish making it to the Golden Gate and the Pacific Ocean. These survival estimates are some of the lowest ever recorded for salmon out-migrating to the Pacific Ocean, with much of the mortality occurring within Mill Creek and the Sacramento River. Cumulative survival through Mill Creek (rkm 452--441) was 68% (+/-12 S.E.), and cumulative survival through the Sacramento River (rkm 441--203) was 7.6% (+/- 16 S.E.) These low survival rates are likely attributed to low flows in Mill Creek and the Sacramento River resulting from critically dry winters between 2013 and 2015, which were reduced even further by water diversions for agriculture in both Mill Creek and the Sacramento River. During periods of higher flow in 2016 survival rates dramatically increased, suggesting that more water in Mill Creek and the Sacramento River is necessary to improve in-river smolt migration survival during the late spring.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9780355131680Subjects--Topical Terms:

1178855
Biological oceanography.
Index Terms--Genre/Form:

554714
Electronic books.

Out-Migration Survival of Wild Chinook Salmon (Oncorhynchus tshawytscha) Smolts from Mill Creek through the Sacramento River during Drought Conditions.
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245 1 0 $a Out-Migration Survival of Wild Chinook Salmon (Oncorhynchus tshawytscha) Smolts from Mill Creek through the Sacramento River during Drought Conditions.
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500 $a Source: Masters Abstracts International, Volume: 56-06.
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504 $a Includes bibliographical references
520 $a Once emerged from the gravel after being spawned in natal streams, Chinook salmon spend many months rearing and growing in freshwater before undergoing smoltification and out-migrating to the ocean. This relatively short period of time is considered to be the most vulnerable and dangerous phase in the life cycle of a Pacific salmon. It is during this phase when smolts navigate around many anthropogenic structures and experience environmental stressors while making their way to the ocean. In California's Central Valley, the few remaining wild populations of Chinook salmon (Oncorhynchus tshawytscha) out-migrate through a highly modified riverine and estuary landscape characterized by leveed banks, altered flow and temperature regimes, transformed food webs, and limited floodplain and rearing habitat. Juvenile salmon smolts migrate through these landscapes within a relatively short period of time, requiring them to quickly adapt to changing water conditions and habitat types. Understanding the survival rates of wild smolts from source tributaries to the Pacific Ocean is essential in protecting and restoring these populations from the low abundances currently observed. When faced with drought conditions out-migrating smolts experience low flows, elevated water temperatures and high densities of predators while out-migrating to sea. In order to assess smolt survival during drought conditions in late spring (April-May), 304 wild smolts were acoustically tagged and tracked from Mill Creek (Tehama County) to the Pacific Ocean between 2013 and 2016. Total outmigration survival to the ocean was 0.3% during these years, with only one fish making it to the Golden Gate and the Pacific Ocean. These survival estimates are some of the lowest ever recorded for salmon out-migrating to the Pacific Ocean, with much of the mortality occurring within Mill Creek and the Sacramento River. Cumulative survival through Mill Creek (rkm 452--441) was 68% (+/-12 S.E.), and cumulative survival through the Sacramento River (rkm 441--203) was 7.6% (+/- 16 S.E.) These low survival rates are likely attributed to low flows in Mill Creek and the Sacramento River resulting from critically dry winters between 2013 and 2015, which were reduced even further by water diversions for agriculture in both Mill Creek and the Sacramento River. During periods of higher flow in 2016 survival rates dramatically increased, suggesting that more water in Mill Creek and the Sacramento River is necessary to improve in-river smolt migration survival during the late spring.
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538 $a Mode of access: World Wide Web
650 4 $a Biological oceanography. $3 1178855
650 4 $a Limnology. $3 907182
650 4 $a Ecology. $3 575279
650 4 $a Aquatic sciences. $3 1178821
655 7 $a Electronic books. $2 local $3 554714
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710 2 $a University of California, Santa Cruz. $b Ocean Sciences. $3 1186054
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