A consistent approach to definitions and symbols in fisheries acoustics
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In this paper, the volume, area, and line coefficients relevant to multiple, distributed targets are defined, leading to practical formulas for the important application of remote biomass estimation from echo-integration.Abstract:
Long-standing problems with acoustical terminology in fisheries applications such as echo-integration indicate the need for a more consistent approach. Based where possible on existing terms, a scheme of explicitly named quantities is proposed, backed by clearly stated definitions and preferred symbols. The emphasis is on scattering phenomena because the terminology in this area presents the main source of difficulty. Starting with the scattering equations for a small target, the volume, area, and line coefficients relevant to multiple, distributed targets are defined, leading to practical formulas for the important application of remote biomass estimation from echo-integration. The aim is to incorporate, as far as possible, common practice in fisheries-acoustics terminology and related fields. The developed scheme has been commended by the ICES Fisheries Acoustics Science and Technology Working Group as a constructive approach to better communication standards in fisheries-acoustics publications.read more
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Climate impacts on eastern Bering Sea foodwebs: a synthesis of new data and an assessment of the Oscillating Control Hypothesis
George L. Hunt,Kenneth O. Coyle,Lisa B. Eisner,Edward V. Farley,Ron A. Heintz,Franz J. Mueter,Jeffrey M. Napp,James E. Overland,Patrick H. Ressler,Sigrid Salo,Phyllis J. Stabeno +10 more
TL;DR: Hunt et al. as discussed by the authors presented a synthesis of new data and an assessment of the Oscillating Control Hypothesis, which indicated bottom-up constraints on pollock recruitment in very warm periods.
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From small‐scale habitat loopholes to decadal cycles: a habitat‐based hypothesis explaining fluctuation in pelagic fish populations off Peru
TL;DR: In this paper, an integrated approach evaluated how fish responded to habitat variation, and determined the consequences in terms of fish-population variability, concluding that during El Nino 1997-98, anchovy was able to exploit a small-scale temporal and spatial "loophole" inside the general unfavourable conditions.
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A post-processing technique to estimate the signal-to-noise ratio and remove echosounder background noise
TL;DR: A simple and effective post-processing technique to estimate echosounder background-noise levels and signal-to-noISE ratios (SNRs) during active pinging is developed, which provides repeated noise estimates over short intervals of time without user intervention, beneficial in cases where background noise changes over time.
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Critical Population Density Triggers Rapid Formation of Vast Oceanic Fish Shoals
Nicholas C. Makris,Purnima Ratilal,Srinivasan Jagannathan,Zheng Gong,Mark Andrews,Ioannis Bertsatos,Olav Rune Godø,Redwood W. Nero,J. Michael Jech +8 more
TL;DR: By quantifying the formation processes of vast oceanic fish shoals during spawning, it is shown that a rapid transition from disordered to highly synchronized behavior occurs as population density reaches a critical value and general theoretical predictions believed to apply in nature irrespective of animal species are confirmed.
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Mesoscale eddies are oases for higher trophic marine life.
Olav Rune Godø,Annette Samuelsen,Gavin J. Macaulay,Ruben Patel,Solfrid Sætre Hjøllo,John K. Horne,Stein Kaartvedt,Stein Kaartvedt,Johnny A. Johannessen +8 more
TL;DR: This work shows that anticyclonic eddies shape distribution and density of marine life from the surface to bathyal depths and demonstrates that they provide rich feeding habitat for higher trophic marine life.
References
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TL;DR: The fundamental principles of underwater sound propagation are described in this paper, which is an authoritative reference for specialists in acoustics, oceanography, marine biology, and related fields, and also encourages a new generation of scientists, engineers and entrepreneurs to apply the modern methods of acoustical physics to probe the unknown sea.
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Physical measurement with modern echo integrators
TL;DR: In this article, the authors define the area backscattering coefficient, which is a most convenient and simple quantity, and describe the essence of absolute calibration by means of a standard target, which follows an established, routine procedure.