Low frequency acoustic imaging of Pacific salmon on the high seas

1996 ◽  
Vol 53 (11) ◽  
pp. 2513-2523 ◽  
Author(s):  
R W Nero ◽  
M E Huster
Keyword(s):  
Pacific Salmon ◽  
Low Frequency ◽  
Acoustic Imaging ◽  
High Seas

Delineating a cased borehole in unconsolidated formations using dipole acoustic data from a nearby well

Geophysics ◽  
2021 ◽  
pp. 1-39
Author(s):  
Gu Xihao ◽  
Xiao-Ming Tang ◽  
Yuan-Da Su
Keyword(s):  
Shear Waves ◽  
Low Frequency ◽  
Well Being ◽  
Compressional Wave ◽  
Acoustic Imaging ◽  
Wave Radiation ◽  
Dipole Source ◽  
Compressional Waves ◽  
Single Well ◽  
Cased Borehole

A potential application for single-well acoustic imaging is the detection of an existing cased borehole in the vicinity of the well being drilled, which is important for drilling toward (when drilling a relief well), or away from (collision prevention), the existing borehole. To fulfill this application in the unconsolidated formation of shallow sediments, we propose a detection method using the low-frequency compressional waves from dipole acoustic logging. For this application, we perform theoretical analyses on elastic wave scattering from the cased borehole and derive the analytical expressions for the scattered wavefield for the incidence of compressional and shear waves from a borehole dipole source. The analytical solution, in conjunction with the elastic reciprocity theorem, provides a fast algorithm for modeling the whole process of wave radiation, scattering, and reception for the borehole acoustic detection problem. The analytical results agree well with those from 3D finite-difference simulations. The results show that compressional waves, instead of shear waves as commonly used for dipole acoustic imaging, are particularly advantageous for the borehole detection in the unconsolidated formation. Field data examples are used to demonstrate the application in a shallow marine environment, where dipole-compressional wave data in the measurement well successfully delineate a nearby cased borehole, validating our analysis results and application.

On the Statistical Distribution of Salmon in the Sea: Application of the Negative Binomial Distribution, and the Influence of Sampling Effort

1993 ◽  
Vol 50 (5) ◽  
pp. 1029-1038 ◽  
Author(s):  
David W. Welch ◽  
Yukimasa Ishida
Keyword(s):  
Negative Binomial Distribution ◽  
Binomial Distribution ◽  
Degrees Of Freedom ◽  
Negative Binomial ◽  
Pacific Salmon ◽  
Sampling Effort ◽  
Gill Net ◽  
Catch Statistics ◽  
Sampling Statistics ◽  
High Seas

We examined the sampling statistics of Pacific salmon (Oncorhynchus spp.) caught in a series of experimental gillnet sets on the high seas and demonstrate how the reliability of the catch statistics varies with the amount of sampling effort. Our analysis indicates that the replicate catches, which were made under essentially identical conditions, are adequately described by the negative binomial distribution. We also extend the utility of this distribution for describing catch statistics by showing that (1) the shape parameter of the distribution can be directly interpreted as the number of degrees of freedom (df) associated with each observation of catch and (2) the df are related to the amount of sampling effort used and the size of the biological aggregation being encountered by the gear. For salmon caught on the high seas, approximately 1 df is obtained per 15 m of gill net used. Identification of the statistical model describing the uncertainty in high-seas gillnet catches should help in the design of better high seas surveys and in the analysis of historical data bases. As an example, we show how the statistical certainty associated with estimates of salmon density changes with the amount of sampling effort applied.

Pacific Salmon (Oncorhynchus) Migrations: Orientation versus Random Movement

1984 ◽  
Vol 41 (9) ◽  
pp. 1319-1324 ◽  
Author(s):  
Thomas P. Quinn ◽  
Cornelis Groot
Keyword(s):  
Computer Simulation ◽  
Swimming Speed ◽  
Pacific Salmon ◽  
Current Knowledge ◽  
Open Ocean ◽  
Important Paper ◽  
Random Movement ◽  
Strong Orientation ◽  
High Seas

A computer simulation by Saila and Shappy (1963. J. Cons. Int. Explor. Mer 28: 153–166) indicated that the migrations of Pacific salmon (Oncorhynchus) from high seas feeding areas to the coastal vicinity of their natal stream may be accomplished with only slight homeward orientation. Five assumptions in this important paper are here reexamined to determine the validity of the original conclusion in light of current knowledge of Pacific salmon biology. It appears that assumptions concerning swimming speed, duration of migration, and return success were incorrect. These errors resulted in substantially underestimating the extent of salmon homeward orientation. Thus, contrary to the original conclusion, any hypothesis concerning the high seas migrations of salmon must explain the strong orientation of these fishes in the open ocean.

scholarly journals Robust Acoustic Imaging Based on Bregman Iteration and Fast Iterative Shrinkage-Thresholding Algorithm

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7298
Author(s):  
Linsen Huang ◽  
Shaoyu Song ◽  
Zhongming Xu ◽  
Zhifei Zhang ◽  
Yansong He
Keyword(s):  
Large Scale ◽  
Near Field ◽  
Low Frequency ◽  
Acoustic Imaging ◽  
Far Field ◽  
Frequency Range ◽  
Bregman Iteration ◽  
Iterative Shrinkage ◽  
Thresholding Algorithm ◽  
Iterative Shrinkage Thresholding

The acoustic imaging (AI) technique could map the position and the strength of the sound source via the signal processing of the microphone array. Conventional methods, including far-field beamforming (BF) and near-field acoustic holography (NAH), are limited to the frequency range of measured objects. A method called Bregman iteration based acoustic imaging (BI-AI) is proposed to enhance the performance of the two-dimensional acoustic imaging in the far-field and near-field measurements. For the large-scale ℓ1 norm problem, Bregman iteration (BI) acquires the sparse solution; the fast iterative shrinkage-thresholding algorithm (FISTA) solves each sub-problem. The interpolating wavelet method extracts the information about sources and refines the computational grid to underpin BI-AI in the low-frequency range. The capabilities of the proposed method were validated by the comparison between some tried-and-tested methods processing simulated and experimental data. The results showed that BI-AI separates the coherent sources well in the low-frequency range compared with wideband acoustical holography (WBH); BI-AI estimates better strength and reduces the width of main lobe compared with ℓ1 generalized inverse beamforming (ℓ1-GIB).

Potential climate change impacts on thermal habitats of Pacific salmon (Oncorhynchus spp.) in the North Pacific Ocean and adjacent seas

2011 ◽  
Vol 68 (9) ◽  
pp. 1660-1680 ◽  
Author(s):  
Omar I. Abdul-Aziz ◽  
Nathan J. Mantua ◽  
Katherine W. Myers
Keyword(s):  
Climate Change ◽  
North Pacific ◽  
Pacific Salmon ◽  
North Pacific Ocean ◽  
Global Climate Model ◽  
Gulf Of Alaska ◽  
Oncorhynchus Keta ◽  
Climate Change Scenarios ◽  
Entire Study ◽  
High Seas

We developed spatially explicit representations for seasonal high-seas (open ocean) thermal habitats for six species of Pacific salmon ( Oncorhynchus  spp.) and evaluated the effects of natural climate variability and projected changes under three Intergovernmental Panel on Climate Change scenarios of future greenhouse gas emissions. Changes in high-seas habitat due to natural climatic variation in 20th century were small relative to that under anthropogenic climate change scenarios for the middle to late 21st century. Under a multimodel ensemble average of global climate model outputs using A1B (medium) emissions scenario for the entire study area (North Pacific and part of Arctic Ocean), projected winter habitats of sockeye ( Oncorhynchus nerka ) decreased by 38%, and summer habitat decreased by 86% for Chinook ( Oncorhynchus tshawytscha ), 45% for sockeye, 36% for steelhead ( Oncorhynchus mykiss ), 30% for coho ( Oncorhynchus kisutch ), 30% for pink ( Oncorhynchus gorbuscha ), and 29% for chum ( Oncorhynchus keta ) salmon by 2100. Reductions were 25% lower for B1 (lower) emissions and 7% higher for A2 (higher) emissions scenarios. Projected habitat losses were largest in the Gulf of Alaska and western and central subarctic North Pacific. Nearly complete losses of Gulf of Alaska habitat for sockeye in both seasons and Chinook in summer raise important policy issues for North American fishery managers and governments.

Contemporary Practice of the United States Relating to International Law

1992 ◽  
Vol 86 (4) ◽  
pp. 792-810
Author(s):  
Marian Nash
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
Marine Mammals ◽  
Pacific Salmon ◽  
North Pacific Ocean ◽  
The United States ◽  
Anadromous Fish ◽  
The North ◽  
The North Pacific ◽  
High Seas

On May 19, 1992, President George Bush transmitted to the Senate for advice and consent to ratification the Convention for the Conservation of Anadromous Stocks in the North Pacific Ocean, with Annex, signed at Moscow on February 11, 1992. An accompanying report by Secretary of State James A. Baker III, dated May 14, 1992, stated, in major part: The Convention has as its centerpiece a prohibition on high seas fishing for Pacific salmon, which will protect valuable migrating U.S.-origin salmonids. It also establishes a new international organization to promote the conservation of anadromous stocks (primarily Pacific salmon) throughout their migratory range in the high seas area of the North Pacific Ocean and its adjacent seas, as well as ecologically related species that interact with these resources, including various marine mammals, seabirds, and non-anadromous fish species. The new organization, which is to be known as the North Pacific Anadromous Fish Commission, will also serve as a needed venue for consultation and coordination of high seas fishery enforcement activities by the contracting parties.

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