Experimental measurement of hydrosystem-induced delayed mortality in juvenile Snake River spring Chinook salmon (Oncorhynchus tshawytscha) using a large-scale acoustic array

2009 ◽  
Vol 66 (7) ◽  
pp. 1019-1024 ◽  
Author(s):  
Erin L. Rechisky ◽  
David W. Welch ◽  
Aswea D. Porter ◽  
Melinda C. Jacobs ◽  
Adrian Ladouceur
Keyword(s):  
Pacific Ocean ◽  
Chinook Salmon ◽  
Large Scale ◽  
Oncorhynchus Tshawytscha ◽  
Fork Length ◽  
Snake River ◽  
Return Rates ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Delayed Mortality

Out-migrating Snake River salmon smolts must pass eight major hydro dams before reaching the Pacific Ocean. Direct mortality at the dams is generally low; however, the cumulative stress caused by dam passage is hypothesized to result in delayed mortality, which occurs beyond the impounded section of the river. We tested the delayed mortality hypothesis by comparing in-river and early ocean survival of hatchery-origin spring Chinook salmon ( Oncorhynchus tshawytscha ) from the Snake River to a mid-Columbia River population that passes through only four dams and has higher smolt to adult return rates. Smolts >140 mm fork length were implanted with acoustic transmitters and tracked with the Pacific Ocean Shelf Tracking (POST) array to as far as Alaska. There was no detectable difference in survivorship to the first ocean detection line, 274 km beyond the final dam (SSnake = 29% ± 4%, SYakima = 28% ± 5%), indicating that the survival disparity observed in adult return rates may develop later in the marine life history phase. Our study is the first to estimate survival in the coastal ocean and demonstrates the utility of a large-scale array in testing previously intractable hypotheses.

CALCULATION OF THE MAGNETIZATION OF UPLIFTS FROM COMBINING TOPOGRAPHIC AND MAGNETIC SURVEYS

Geophysics ◽  
1967 ◽  
Vol 32 (4) ◽  
pp. 678-707 ◽  
Author(s):  
M. L. Richards ◽  
V. Vacquier ◽  
G. D. Van Voorhis
Keyword(s):  
Pacific Ocean ◽  
Horizontal Plane ◽  
Large Scale ◽  
Geomagnetic Latitude ◽  
Pole Position ◽  
Present Position ◽  
Paleomagnetic Pole ◽  
The Pacific ◽  
Geomagnetic Pole ◽  
The Pacific Ocean

The direction and magnitude of the magnetization of a uniformly magnetized structure can be computed by combining topographic and magnetic surveys. The previously reported method has been extended to include more than one structure, each possessing its particular magnetization. Also, the bottom of the structure need not be a horizontal plane but can be an arbitrary surface. The method was applied to 21 seamounts, one laccolith and two Aleutian volcanoes. Four of the seamounts were found to be reversely magnetized. The virtual paleomagnetic pole positions for 16 Pacific Ocean seamounts, representing three widely separated locations, are significantly different from the present geomagnetic pole position but near Mesozoic virtual pole positions from Australia. For two locations, radiometric age determinations give an average date for their formation in the Cretaceous. The apparent 30 degree shift in geomagnetic latitude of the seamounts is interpreted as the result of large scale movements of the Pacific Ocean floor or, alternatively, as the result of the paleomagnetic equator being north of its present position in the Pacific during the growth of the seamounts.

scholarly journals Can seafloor voltage cables be used to study large-scale circulation? An investigation in the Pacific Ocean

Ocean Science ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. 383-392
Author(s):  
Jakub Velímský ◽  
Neesha R. Schnepf ◽  
Manoj C. Nair ◽  
Natalie P. Thomas
Keyword(s):  
Pacific Ocean ◽  
Flow Velocity ◽  
Ocean Circulation ◽  
Large Scale ◽  
Eastern Pacific ◽  
Low Flow ◽  
Large Scale Circulation ◽  
Numerical Predictions ◽  
The Pacific ◽  
The Pacific Ocean

Abstract. Marine electromagnetic (EM) signals largely depend on three factors: flow velocity, Earth's main magnetic field, and seawater's electrical conductivity (which depends on the local temperature and salinity). Because of this, there has been recent interest in using marine EM signals to monitor and study ocean circulation. Our study utilizes voltage data from retired seafloor telecommunication cables in the Pacific Ocean to examine whether such cables could be used to monitor circulation velocity or transport on large oceanic scales. We process the cable data to isolate the seasonal and monthly variations and then evaluate the correlation between the processed data and numerical predictions of the electric field induced by an estimate of ocean circulation. We find that the correlation between cable voltage data and numerical predictions strongly depends on both the strength and coherence of the model velocities flowing across the cable, the local EM environment, as well as the length of the cable. The cable within the Kuroshio Current had good correlation between data and predictions, whereas two of the cables in the Eastern Pacific Gyre – a region with both low flow speeds and interfering velocity directions across the cable – did not have any clear correlation between data and predictions. Meanwhile, a third cable also located in the Eastern Pacific Gyre showed good correlation between data and predictions – although the cable is very long and the speeds were low, it was located in a region of coherent flow velocity across the cable. While much improvement is needed before utilizing seafloor voltage cables to study and monitor oceanic circulation across wide regions, we believe that with additional work, the answer to the question of whether or not seafloor voltage cables can be used to study large-scale circulation may eventually be yes.

scholarly journals Two-year optical site characterization for the Pacific Ocean Neutrino Experiment (P-ONE) in the Cascadia Basin

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
Nicolai Bailly ◽  
Jeannette Bedard ◽  
Michael Böhmer ◽  
Jeff Bosma ◽  
Dirk Brussow ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Large Scale ◽  
Neutrino Experiment ◽  
Attenuation Length ◽  
Mooring Lines ◽  
Absorption Length ◽  
Neutrino Telescopes ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean

AbstractThe STRings for Absorption length in Water (STRAW) are the first in a series of pathfinders for the Pacific Ocean Neutrino Experiment (P-ONE), a future large-scale neutrino telescope in the north-eastern Pacific Ocean. STRAW consists of two $$150\,\mathrm {m}$$ 150 m long mooring lines instrumented with optical emitters and detectors. The pathfinder is designed to measure the attenuation length of the water and perform a long-term assessment of the optical background at the future P-ONE site. After 2 years of continuous operation, measurements from STRAW show an optical attenuation length of about 28 m at $$450\,\mathrm {nm}$$ 450 nm . Additionally, the data allow a study of the ambient undersea background. The overall optical environment reported here is comparable to other deep-water neutrino telescopes and qualifies the site for the deployment of P-ONE.

Can seafloor voltage cables be used to study large scale transport? An investigation in the Pacific Ocean.

2020 ◽  
Author(s):  
Neesha Schnepf ◽  
Manoj Nair ◽  
Jakub Velimsky ◽  
Natalie Thomas
Keyword(s):  
Pacific Ocean ◽  
Ocean Circulation ◽  
Large Scale ◽  
Eastern Pacific ◽  
Clear Correlation ◽  
Numerical Predictions ◽  
Main Challenge ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Oceanic Transport

<p>Marine electromagnetic (EM) signals largely depend on three factors: oceanic transport (i.e., depth-integrated flow), the local main magnetic field, and the local seawater conductivity (which depends on the local temperature and salinity). Thus, there is interest in using seafloor telecommunication cables to isolate marine EM signals and study ocean processes because these cables measure voltage differences between their two ends. Data from such cables can provide information on the depth-integrated transport occurring in the water column above the cable. However, these time-varying data are a superposition of all EM fields present at the observatory, no matter what source or process created the field. The main challenge in using such submarine voltage cables to study ocean circulation is properly isolating its signal.</p><p> </p><p>Our study utilizes voltage data from retired seaoor telecommunication cables in the Pacific Ocean to examine whether such cables could be used to monitor transport on large-oceanic scales. We process the cable data to isolate the seasonal and monthly variations, and evaluate the correlation between the processed data and numerical predictions of the electric field induced by ocean circulation. We find that the correlation between cable voltage data and numerical predictions strongly depends on both the strength and coherence of the transport owing across the cable. The cable within the Kuroshio Current had the highest correlation between data and predictions, whereas two of the cables in the Eastern Pacific gyre (a region with both low transport values and interfering transport signals across the cable) did not have any clear correlation between data and predictions. Meanwhile, a third cable also located in the Eastern Pacific gyre did have correlation between data and predictions, because although the transport values were low, it was located in a region of coherent transport flow across the cable. While much improvement is needed before utilizing seafloor voltage cables to study and monitor oceanic transport across wide oceanic areas, we believe that the answer to our title's questions is yes: seafloor voltage cables can eventually be used to study large-scale transport.</p>

Zooplankton communities in the Strait of Georgia, British Columbia, track large-scale climate forcing over the Pacific Ocean

2013 ◽  
Vol 115 ◽  
pp. 90-102 ◽  
Author(s):  
Lingbo Li ◽  
Dave Mackas ◽  
Brian Hunt ◽  
Jake Schweigert ◽  
Evgeny Pakhomov ◽  
...  
Keyword(s):  
British Columbia ◽  
Pacific Ocean ◽  
Large Scale ◽  
Climate Forcing ◽  
Strait Of Georgia ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Zooplankton Communities

Evaluating river management during seaward migration to recover Columbia River stream-type Chinook salmon considering the variation in marine conditions

2014 ◽  
Vol 71 (2) ◽  
pp. 259-271 ◽  
Author(s):  
Howard A. Schaller ◽  
Charles E. Petrosky ◽  
Eric S. Tinus
Keyword(s):  
Marine Environment ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Columbia River ◽  
Temporal Analysis ◽  
Adult Survival ◽  
Snake River ◽  
Data Sets ◽  
Delayed Mortality ◽  
Stream Type

Evidence suggests Snake River stream-type Chinook salmon (Oncorhynchus tshawytscha) experience substantial delayed mortality in the marine environment as a result of their outmigration experience through the Federal Columbia River Power System (FCRPS). We analyzed mortality patterns using methods that incorporated downriver reference populations passing fewer dams, and temporal approaches that were independent of reference populations. Our results from the alternative spatial and temporal methods consistently corroborated with spawner–recruit residuals and smolt-to-adult survival rate data sets, indicating that Snake River salmon survived about one quarter as well as the reference populations. Temporal analysis indicated that a high percentage (76%) of Snake River juvenile salmon that survived the FCRPS subsequently died in the marine environment as a result of their outmigration experience. Through this and previous studies, it is evident that delayed hydrosystem mortality increases with the number of powerhouse passages and decreases with the speed of outmigration. Therefore, a promising conservation approach would be to explore management experiments that evaluate these relationships by increasing managed spill levels at the dams during the spring migration period.

Going Big in the Pacific

2020 ◽  
Vol 5 (1) ◽  
pp. 186-204 ◽  
Author(s):  
Quentin Hanich ◽  
Clive Schofield ◽  
Chris Smyth
Keyword(s):  
Pacific Ocean ◽  
Protected Areas ◽  
Marine Protected Areas ◽  
Large Scale ◽  
Marine Conservation ◽  
Global Ocean ◽  
Conservation Targets ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Definition Of

The definition of large-scale marine protected areas in the Pacific Ocean is fundamental to the achievement of global marine conservation targets. The threatened nature of the global ocean is emphasised, the evolution of global spatial targets for marine conservation outlined and the implementation of large-scale marine protected areas in Australia and the Pacific Ocean more broadly is reviewed. The article concludes with some reflections on the efficacy of such mechanisms in the Pacific.

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