Acoustic models of fish: The Atlantic cod (Gadus morhua)
01 Sep 1994-Journal of the Acoustical Society of America (Acoustical Society of America)-Vol. 96, Iss: 3, pp 1661-1668
TL;DR: In this paper, anesthetized live Atlantic cod ranging from 156 to 380 mm (SL) x-rayed to image inflated swimbladders and skeletal elements were used to model the acoustic scattering function of teleost fish.
Abstract: Acoustic fish models should represent the fish body form. The Atlantic cod were used to model the acoustic scattering function of teleost fish. The model provides a basis for choices of sonar carrier frequencies. Anesthetized live Atlantic cod ranging from 156 to 380 mm (SL) were ‘‘soft’’ x‐rayed to image inflated swimbladders and skeletal elements. Maximum body heights and widths were 0.18 and 0.13 of fish lengths. Lengths and diameters of swimbladder were approximately 0.25 and 0.05 of the fish lengths. A series of short‐length fluid‐filled cylinders were used to represent body flesh. For carrier frequencies above the breathing mode resonance, swimbladders were modeled as a series of short gas‐filled volume elements of cylinders. A Kirchhoff‐ray approximation was used to compute the high‐frequency acoustic scattering. A low mode solution for a gas‐filled cylinder was used to compute the low‐frequency ‘‘breathing mode resonance.’’ All contributions were added coherently. The scattering lengths L, or target strength=20 log‖L/L0‖ (where L0 is reference length) were sensitive to fish orientation relative to the sonar beam. Theoretical target strengths were compared to the 38‐kHz cod data. Agreement was good.
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TL;DR: Exclusive use of acoustics to identify aquatic organisms reliably will require a set of statistical metrics that discriminate among a wide range of similar body types at any packing density, and incorporation of these algorithms in routine data processing.
Abstract: Noninvasive species identification remains a longterm goal of fishers, researchers, and resource managers who use sound to locate, map, and count aquatic organisms. Since the first biological applications of underwater acoustics, four approaches have been used singly or in combination to survey marine and freshwater environments: passive sonar; prior knowledge and direct sampling; echo statistics from high-frequency measures; and matching models to low-frequency measures. Echo amplitudes or targets measured using any sonar equipment are variable signals. Variability in reflected sound is influenced by physical factors associated with the transmission of sound through a compressible fluid, and by biological factors associated with the location, reflective properties, and behaviour of a target. The current trend in acoustic target identification is to increase the amount of information collected through increases in frequency bandwidth or in the number of acoustic beams. Exclusive use of acoustics to identify aquatic organisms reliably will require a set of statistical metrics that discriminate among a wide range of similar body types at any packing density, and incorporation of these algorithms in routine data processing.
238 citations
Cites background or methods from "Acoustic models of fish: The Atlant..."
...Medial axes of swimbladders typically deviate 5±10° from ®sh body sagittal axes (see ®g. 2 in Clay and Horne, 1994)....
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...…in backscatter amplitudes among ®sh, mean reduced scattering lengths were estimated for nine 200 mm Atlantic cod using Kirchhoff-ray mode backscatter models (Clay and Horne, 1994) and plotted as a function of organism length L, acoustic wavelength k, and ®sh aspect angle h (lower surface; Fig....
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TL;DR: Fish-eating "resident"-type killer whales (Orcinus orca) that frequent the coastal waters off northeastern Vancouver Island, Canada have a strong preference for chinook salmon, and echo levels from the echolocation signals are estimated for different horizontal ranges between a whale and a salmon.
Abstract: Fish-eating “resident”-type killer whales (Orcinus orca) that frequent the coastal waters off northeastern Vancouver Island, Canada have a strong preference for chinook salmon (Oncorhynchus tshawytscha). The whales in this region often forage along steep cliffs that extend into the water, echolocating their prey. Echolocation signals of resident killer whales were measured with a four-hydrophone symmetrical star array and the signals were simultaneously digitized at a sample rate of 500 kHz using a lunch-box PC. A portable VCR recorded the images from an underwater camera located adjacent to the array center. Only signals emanating from close to the beam axis (1185 total) were chosen for a detailed analysis. Killer whales project very broadband echolocation signals (Q equal 0.9 to 1.4) that tend to have bimodal frequency structure. Ninety-seven percent of the signals had center frequencies between 45 and 80 kHz with bandwidths between 35 and 50 kHz. The peak-to-peak source level of the echolocation signal...
127 citations
TL;DR: This study presents a new probabilistic procedure that allows for real-time analysis of the response of the immune system to infectious diseases such as diarrhoea and septicaemia in Response to infectious disease.
Abstract: © 2010 The Authors. This article is distributed under the terms of the Creative Commons Attribution-Noncommercial License. The definitive version was published in ICES Journal of Marine Science: Journal du Conseil 67 (2010): 365-378, doi:10.1093/icesjms/fsp262.
119 citations
Cites methods from "Acoustic models of fish: The Atlant..."
...higher frequencies, a model is used to describe geometrical (nonresonant) scattering effects by the swimbladder, such as those associated with orientation (Clay, 1991, 1992; Clay and Horne, 1994; Chu et al., 2006)....
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...…ic.oup.com /icesjm s/article-abstract/67/2/365/696001 by guest on 03 April 2019 higher frequencies, a model is used to describe geometrical (nonresonant) scattering effects by the swimbladder, such as those associated with orientation (Clay, 1991, 1992; Clay and Horne, 1994; Chu et al., 2006)....
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TL;DR: T thorough validation, or "ground-truthing", of the species composition, depth structure, population size distribution, capture efficiency of the sampling device, and acoustic properties of the fish present is critical for credible acoustic estimates of mesopelagic fish biomass.
Abstract: Acoustic survey methods are useful to estimate the distribution, abundance, and biomass of mesopelagic fish, a key component of open ocean ecosystems. However, mesopelagic fish pose several challenges for acoustic biomass estimation based on their small size, wide depth range, mixed aggregations, and length-dependent acoustic reflectance, which differentiate them from the larger epipelagic and neritic fish for which these methods were developed. Foremost, there is a strong effect of depth on swimbladder resonance, so acoustic surveys of mesopelagic fish must incorporate depth-stratification. Additionally, the 1-3 cm juveniles of many species are not only more abundant, but can also be stronger acoustic backscatterers than the larger adults that comprise most of the biomass. The dominant species in terms of biomass may thus be weak acoustic backscatters. Failure to properly incorporate depth, the full size distribution, and certain less-abundant species into mesopelagic acoustic analyses could lead to errors in estimated biomass of up to three orders of magnitude. Thus, thorough validation, or "ground-truthing ", of the species composition, depth structure, population size distribution, capture efficiency of the sampling device, and acoustic properties of the fish present is critical for credible acoustic estimates of mesopelagic fish biomass. This is not insurmountable, but requires more ancillary data than is usually collected.
104 citations
Cites background from "Acoustic models of fish: The Atlant..."
...076 g ml(21), a typical value for an epipelagic fish (Saenger, 1989; Clay and Horne, 1994; Davison, 2011a)....
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...For purposes of buoyancy calculation and acoustic modelling, fish are commonly assumed to have a body density of 1.076 g ml21, a typical value for an epipelagic fish (Saenger, 1989; Clay and Horne, 1994; Davison, 2011a)....
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TL;DR: This work edited and updated earlier summary regressions relating fish size, acoustic frequency and acoustic cross-section and found significant species and live vs. dead (or stunned) fish effects on the target strength to length relationship.
Abstract: There are many measurements of dorsal aspect target strength of fish, but relatively few studies compare estimation methods or attempt to combine data from different studies into general relations between fish size, acoustic frequency and target strength (or acoustic cross-section). We edited and updated earlier summary regressions relating fish size, acoustic frequency and acoustic cross-section. Experimental measurements on marine fish were separated into swimbladder and non-swimbladder species, model results compared with experimental data, target strengths of marine, and freshwater fish were contrasted, and previous and new target strengths of commercial New Zealand fish species were placed in the context of the new regressions. Analysis of variance was used to show significant effects of species, freshwater vs. marine, swimbladder vs. non-swimbladder fish, model vs. experimental, and dead vs. alive fish on the relationship between maximum dorsal aspect target strength and fish length. For experimental results on gadoids we found significant species and live vs. dead (or stunned) fish effects on the target strength to length relationship. The quadratic dependence of target strength on fish length was also tested and found to be the exception rather than the rule. Existing pitch tilt angle data was compiled and a normal distribution with standard deviation of at least 15° was required to describe most distributions.
87 citations
Cites background or methods from "Acoustic models of fish: The Atlant..."
..., 1996), and a modification of the Kirchhoff method (Clay and Horne, 1994) fall within the trend line for the experimental data (Fig....
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...Many more recent data sets were added (Foote, 1979, using data of Nakken and Olsen, 1977, edited by Foote and Nakken, 1978; Mukai et al., 1993; Clay and Horne, 1994) (Table 1), but some data were not included, e....
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...For model estimates, the type of model is given: 1=mapping method; 2=Do and Surti (1990); 3=Clay and Horne (1994); 4=Stanton (1989)....
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..., 1993) 12 2 24 21 "3 Mummichog Fundulus heteroclitus y M 0 (Love, 1971) 3 8 24 22 "2 Striped killifish Fundulus majalis y M 0 (Love, 1971) 5 8 40 33 "7 Atlantic cod Gadus morhua y M 3 (Clay and Horne, 1994) 4 2 8 8 0 Atlantic cod Gadus morhua 0 (Cushing et al....
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