Target strength
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From siphonophores to deep scattering layers: uncertainty ranges for the estimation of global mesopelagic fish biomass Open
The mesopelagic community is important for downward oceanic carbon transportation and is a potential food source for humans. Estimates of global mesopelagic fish biomass vary substantially (between 1 and 20 Gt). Here, we develop a global m…
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Deep-scattering layer, gas-bladder density, and size estimates using a two-frequency acoustic and optical probe Open
Estimating the biomass of gas-bladdered organisms in the mesopelagic ocean is a simple first step to understanding ecosystem structure. An existing two-frequency (38 and 120 kHz) acoustic and optical probe was lowered to 950 m to estimate …
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Broadband echosounder measurements of the frequency response of fishes and euphausiids in the Gulf of Alaska Open
Broadband acoustic scattering techniques are not widely used in fisheries acoustics, but this may change due to the recent commercial availability of a broadband echosounder system operating at frequencies commonly used in fisheries survey…
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Fish hydroacoustic survey standardization: A step forward based on comparisons of methods and systems from vertical surveys of a large deep lake Open
Hydroacoustic methods are routinely used for fish population assessment and monitoring in lakes and reservoirs around the world and are particularly embedded in European and North American lake management. However, the comparability of hyd…
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Exploring the promise of broadband fisheries echosounders for species discrimination with quantitative assessment of data processing effects Open
It remains an open question how well the increased bandwidth afforded by broadband echosounders can improve species discrimination in fisheries acoustics. Here, an objective statistical approach was used to determine if there is informatio…
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A model based on data from echosounder buoys to estimate biomass of fish species associated with fish aggregating devices Open
Most of the drifting fish aggregating devices (DFADs) used in industrial tropical tuna purse seine fisheries are equipped with satellite linked echosounder buoys, which provide fishing crews with remote, accurate geolocation information an…
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Classification of Southern Ocean krill and icefish echoes using random forests Open
Target identification remains a challenge for acoustic surveys of marine fauna. Antarctic krill, Euphausia superba, are typically identified through a combination of expert scrutiny of echograms and analysis of differences in mean volume b…
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Investigation and Numerical Simulation of the Acoustic Target Strength of the Underwater Submarine Vehicle Open
Modern weapon systems’ survival hinges on their detection capabilities more than anything else. In the active sonar equation, the acoustic target strength is crucial. Under the assumption of plane wave propagation, the standard target stre…
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Effects of variable mean target strength on estimates of abundance: the case of Atlantic mackerel (Scomber scombrus) Open
Atlantic mackerel Scomber scombrus is a small pelagic, migratory fish which supports commercial fisheries. These fish school and are detectable using echosounders, yet fishery-independent estimates of their abundance in the North East Atla…
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Determination of Optimal Acoustic Passive Reflectors to Reduce Bycatch of Odontocetes in Gillnets Open
The need to minimize bycatch of toothed whales (odontocetes) in gillnets has long been recognized, because they are often top predators and thus essential to ecosystem resilience. It is likely that a key to achieving this goal is the impro…
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Target strength of skipjack tuna (Katsuwanus pelamis) associated with fish aggregating devices (FADs) Open
This paper presents measures of target strength (TS; dB re 1 m2) and models of TS vs. fork length (L; cm), i.e. TS=20logL+b20, for skipjack tuna associated with fish aggregating devices (FADs) in the Central Pacific Ocean. Measurements wer…
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Observations of in situ Atlantic bluefin tuna (Thunnus thynnus) with 500-kHz multibeam sonar Open
Field studies to investigate the survey capability of a 500-kHz multibeam sonar to monitor and quantify Atlantic bluefin tuna were undertaken at several fishing locations (commercial and recreational) off Prince Edward Island and at a grow…
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Measurement of Seafloor Acoustic Backscatter Angular Dependence at 150 kHz Using a Multibeam Echosounder Open
Acoustic seafloor measurements with multibeam echosounders (MBESs) are currently often used for submarine habitat mapping, but the MBESs are usually not acoustically calibrated for backscattering strength (BBS) and cannot be used to infer …
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Frequency- and depth-dependent target strength measurements of individual mesopelagic scatterers Open
Recent estimates based on shipboard echosounders suggest that 50% or more of global fish biomass may reside in the mesopelagic zone (depths of ∼200–1000 m). Nonetheless, little is known about the acoustic target strengths (TS) of mesopelag…
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Estimating target strength and physical characteristics of gas-bearing mesopelagic fish from wideband <i>in situ</i> echoes using a viscous-elastic scattering model Open
Wideband (38 and 50–260 kHz) target strength of organisms were measured in situ using a towed platform in mesopelagic (200–1000 m depth) layers. Organisms with a gas-inclusion are strong scatterers of sound and acoustically distinct from o…
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Acoustic Target Strength Measurements for Biomass Estimation of Aquaculture Fish, Redlip Mullet (Chelon haematocheilus) Open
Redlip mullet (Chelon haematocheilus) is distributed in coastal waters of the North-Western Pacific Ocean and is a cultured fish in Korea. A hydroacoustic technique constitutes a useful method to assess the biomass and spatial distribution…
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Remote sizing of fish-like targets using broadband acoustics Open
Broadband echosounder systems provide very high range resolution that could resolve different parts of fish and hence provide estimates of fish size. The potential for, and accuracy of, direct acoustic sizing of fish was tested on fish-lik…
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Acoustic target strength (TS) of argentine anchovy (Engraulis anchoita): the nighttime scattering layer Open
Engraulis anchoita is a physostomous fish with a dual chambered swimbladder (sb). In situ target strength (TS) measurements on this species are only possible at night, when anchovies disperse forming a scattering layer near the sea surface…
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Submarine Acoustic Target Strength Modeling at High-Frequency Asymptotic Scattering Open
The ability to identify asymptotic scattering is critical for the continuous operation of modern combat systems. In the active sonar equation, acoustic target strength is crucial. The plane-wave propagation target strength equation predict…
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Classification of Sonar Targets in Air: A Neural Network Approach Open
Ultrasonic sonar sensors are commonly used for contactless distance measurements in application areas such as automotive and mobile robotics. They can also be exploited to identify and classify sound-reflecting objects (targets), which may…
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Quantitative processing of broadband data as implemented in a scientific split‐beam echosounder Open
The use of quantitative broadband echosounders for biological studies and surveys can offer considerable advantages over narrowband echosounders. These include improved spectral‐based target identification and significantly increased abili…
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Acoustic systems (split beam echo sounder ) to determine abundance of fish in marine fisheries Open
Acoustic waves are transmitted into the subsurface ocean will experience scattering (scattering) caused by marine organisms, material distributed in the ocean, the structure is not homogeneous in seawater, as well as reflections from the s…
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An Efficient Method for Detection and Quantitation of Underwater Gas Leakage Based on a 300-kHz Multibeam Sonar Open
In recent years, multibeam sonar has become the most effective and sensitive tool for the detection and quantitation of underwater gas leakage and its rise through the water column. Motivated by recent research, this paper presents an effi…
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Improving the Accuracy of Krill Target Strength Using a Shape Catalog Open
Antarctic krill are subject to precautionary catch limits, based on biomass estimates, to ensure human activities do not adversely impact their important ecological role. Accurate target strength models of individual krill underpin biomass…
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Passive and active, predator and prey: using acoustics to study interactions between cetaceans and forage fish Open
Fisheries acoustics surveys provide platforms for deploying passive acoustic equipment to detect cetacean vocalizations. Passive acoustic methods are developing as viable alternatives to visual surveys, particularly for small, inconspicuou…
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A new in-situ method to estimate fish target strength reveals high variability in broadband measurements Open
Acknowledgements The authors thank the Greenland Institute of Natural Resources (GINR), the University of Aberdeen, and Marine Alliance for Science and Technology for Scotland (MASTS) for funding this study. MASTS is funded by the Scottish…
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Accounting for seasonal and composition‐related variability in acoustic material properties in estimating copepod and krill target strength Open
Estimation of abundance or biomass, using acoustic techniques requires knowledge of the frequency dependent acoustic backscatter characteristics, or target strength, of organisms. Target strength of zooplankton is typically estimated from …
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Comparisons of day-time and night-time hydroacoustic surveys in temperate lakes Open
In recent years, due to an increased need for non-intrusive sampling techniques, hydroacoustics has attracted attention in fishery science and management. Efforts to promote standardisation are increasing the accuracy, efficiency, and comp…
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Impacts of Morphological Characteristics on Target Strength of Chub Mackerel (Scomber japonicus) in the Northwest Pacific Ocean Open
Chub mackerel ( Scomber japonicus ) is an important commercial fish in the Northwest Pacific Ocean. Accurate target strength ( TS ) underpins acoustic stock assessment but the TS of S. japonicus is still poorly understood. In this study, t…
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The enhanced effect of collapse strength of a dual-frequency driven bubble in 2-dimensional space Open
The bubble-collapse strength is closely related to the ultrasonic cavitation effect. The enhanced effect of collapse strength of a dual-frequency driven bubble is one of the mechanisms underlying the synergistic effect of dual-frequency ex…