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Article ; Online: Body size- and season-dependent diel vertical migration of mesozooplankton resolved acoustically in the San Diego Trough

Gastauer, Sven / Nickels, Catherine F. / Ohman, Mark D.

2022

Abstract: Diel vertical migration (DVM) is a common behavior among marine organisms to balance the trade-off between surface feeding opportunities and predation-related mortality risk. Body size is a master trait that impacts predation risk to both visual and ... ...

Abstract	Diel vertical migration (DVM) is a common behavior among marine organisms to balance the trade-off between surface feeding opportunities and predation-related mortality risk. Body size is a master trait that impacts predation risk to both visual and nonvisual predators. Acoustic measurements from the autonomous Zooglider revealed size-dependent DVM behaviors in the San Diego Trough. Dual frequency (200 and 1000 kHz) backscatter, in conjunction with physical properties of the ambient water and optical imaging of zooplankton, were recorded during 12 Zooglider missions over 2 yr. Acoustic size-categories were identified based on the theoretical scattering properties of dominant taxonomic groups identified optically by the Zoocam. Acoustic modeling suggests that the measured acoustic backscatter in this region is largely dominated by copepods, with appreciable contributions from other taxa. We found that larger organisms migrated deeper (245–227 m) and faster (> 20 m h−1) compared to smaller organisms (156 m, > 15 m h−1). Larger organisms entered the upper layer of the water column later in the evening (0.2–1.5 h later) and descended into deeper water earlier in the morning (0.4–3.7 h earlier) than smaller-bodied organisms, consistent with body size-dependent visual predation risk. The variability in daytime depths occupied by small, intermediate, and large-bodied backscatterers was related to the depth of the euphotic zone, again consistent with light-dependent risk of predation.
Keywords	Text ; ddc:570
Subject code	551
Language	English
Publishing country	de
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Discrimination between schools and submerged trees in reservoirs: a preliminary approach using narrowband and broadband acoustics

Blanluet, Arthur / Gastauer, Sven / Cattanéo, Franck / Goulon, Chloé / Grimardias, David / Guillard, Jean

Canadian journal of fisheries and aquatic sciences. 2022, v. 79, no. 5

2022

Abstract: With a growing demand for hydroelectric energy, the number of reservoirs is dramatically increasing worldwide. These new water bodies also present an opportunity for the development of fishing activities. However, these reservoirs are commonly impounded ... ...

Abstract	With a growing demand for hydroelectric energy, the number of reservoirs is dramatically increasing worldwide. These new water bodies also present an opportunity for the development of fishing activities. However, these reservoirs are commonly impounded on uncut forests, resulting in many immersed trees. These trees hinder fish assessments by disrupting both gill-netting and acoustic sampling. Immersed trees can easily be confused with fish schools on echograms. To overcome this issue, we developed a method to discriminate fish schools from immersed trees. A random forest algorithm was used to classify echo-traces at 120 and 200 kHz, recorded by an EK80 (SIMRAD) in narrowband (continuous wave) and in broadband mode (frequency modulated). We obtained a good discrimination rate between trees and schools, especially in broadband (90% ratio of good classification). We demonstrate that it is possible to discriminate fish schools from immersed trees and thus facilitate the use of fisheries acoustics in reservoirs.
Keywords	acoustics ; algorithms ; fish ; hydroelectric power
Language	English
Size	p. 738-748.
Publishing place	Canadian Science Publishing
Document type	Article
ZDB-ID	1473089-3
ISSN	1205-7533 ; 0706-652X
ISSN (online)	1205-7533
ISSN	0706-652X
DOI	10.1139/cjfas-2021-0087
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: ZooScatR-An r package for modelling the scattering properties of weak scattering targets using the distorted wave Born approximation.

Gastauer, Sven / Chu, Dezhang / Cox, Martin J

The Journal of the Acoustical Society of America

2019 Volume 145, Issue 1, Page(s) EL102

Abstract: A thorough understanding of the scattering characteristics of marine organisms is a prerequisite for robust quantitative fisheries acoustic data processing or interpretation. Target strength models, such as the distorted wave Born approximation (DWBA) ... ...

Abstract	A thorough understanding of the scattering characteristics of marine organisms is a prerequisite for robust quantitative fisheries acoustic data processing or interpretation. Target strength models, such as the distorted wave Born approximation (DWBA) can be used to improve the understanding of field recordings of weakly scattering targets. With acoustic methods now being used by a wide audience, allowing access to such models becomes a necessity. To ease access to the DWBA model, an r package (zooscatr) which includes a web application and the ability to parameterise the model either through the web application, text files, or pure scripting has been developed and is now freely available on Github.
Language	English
Publishing date	2019-01-30
Publishing country	United States
Document type	Journal Article
ZDB-ID	219231-7
ISSN	1520-8524 ; 0001-4966
ISSN (online)	1520-8524
ISSN	0001-4966
DOI	10.1121/1.5085655
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Article ; Online: Erratum: ZooScatR-An R package for modelling the scattering properties of weak scattering targets using the distorted wave Born approximation [J. Acoust. Soc. Am. 145, EL102-EL108 (2019)].

Gastauer, Sven / Chu, Dezhang / Cox, Martin J

The Journal of the Acoustical Society of America

2019 Volume 145, Issue 3, Page(s) 1426

Language	English
Publishing date	2019-05-15
Publishing country	United States
Document type	Journal Article ; Published Erratum
ZDB-ID	219231-7
ISSN	1520-8524 ; 0001-4966
ISSN (online)	1520-8524
ISSN	0001-4966
DOI	10.1121/1.5094779
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Article ; Online: Extensive oceanic mesopelagic habitat use of a migratory continental shark species.

Schaber, Matthias / Gastauer, Sven / Cisewski, Boris / Hielscher, Nicole / Janke, Michael / Peña, Marian / Sakinan, Serdar / Thorburn, James

Scientific reports

2022 Volume 12, Issue 1, Page(s) 2047

Abstract: The identification of movement and behaviour patterns, as well as inter- and intra-population connectivity is crucial in order to implement effective and functional management and conservation measures for threatened migratory species such as tope ( ... ...

Abstract	The identification of movement and behaviour patterns, as well as inter- and intra-population connectivity is crucial in order to implement effective and functional management and conservation measures for threatened migratory species such as tope (Galeorhinus galeus). Yet, previous studies struggled to elucidate clear and consistent movement and depth usage patterns of adult tope in the Northeast Atlantic, suggesting a high plasticity in the migration and behaviour. We deployed pop-up satellite archival tags on adult tope during their seasonal summer aggregations in the inner German Bight of the south-eastern North Sea and near a presumed mating site in southwest Scotland. Depth distribution and migration pathways were derived from time series data with location processing. Four individuals followed migration trajectories leaving coastal areas and crossed the European shelf slope into oceanic areas of the Northeast Atlantic, remaining fully pelagic for the rest of the deployment duration. These sharks showed far-ranging migration trajectories and undertook regular and frequent diel vertical migrations, reaching daytime depths of over 700 m. Vertical migration patterns closely overlapped with biological mesopelagic habitat structures and closely tracked the diel migration of organisms from deep scattering layers derived from hydroacoustic recordings. It is hypothesized that adult tope regularly utilize oceanic habitats, foraging on mesopelagic layers in an environment generally considered of low prey density.
MeSH term(s)	Animal Migration ; Animals ; Atlantic Ocean ; Behavior, Animal ; Conservation of Natural Resources ; Ecosystem ; Endangered Species ; North Sea ; Oceans and Seas ; Predatory Behavior ; Scotland ; Seasons ; Sharks/physiology
Language	English
Publishing date	2022-02-07
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-022-05989-z
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Article ; Online: Discrimination between schools and submerged trees in reservoirs

Blanluet, Arthur / Gastauer, Sven / Cattanéo, Franck / Goulon, Chloé / Grimardias, David / Guillard, Jean

a preliminary approach using narrowband and broadband acoustics

2022

Abstract	With a growing demand for hydroelectric energy, the number of reservoirs is dramatically increasing worldwide. These new water bodies also present an opportunity for the development of fishing activities. However, these reservoirs are commonly impounded on uncut forests, resulting in many immersed trees. These trees hinder fish assessments by disrupting both gill-netting and acoustic sampling. Immersed trees can easily be confused with fish schools on echograms. To overcome this issue, we developed a method to discriminate fish schools from immersed trees. A random forest algorithm was used to classify echo-traces at 120 and 200 kHz, recorded by an EK80 (SIMRAD) in narrowband (continuous wave) and in broadband mode (frequency modulated). We obtained a good discrimination rate between trees and schools, especially in broadband (90% ratio of good classification). We demonstrate that it is possible to discriminate fish schools from immersed trees and thus facilitate the use of fisheries acoustics in reservoirs. Étant donné la demande croissante d’hydroélectricité, le nombre de réservoirs connaît une augmentation considérable partout sur terre. Ces nouveaux plans d’eau offrent la possibilité de développer de nouvelles activités de pêche. Cependant, ces réservoirs sont souvent aménagés dans des forêts non coupées, entraînant l’immersion de nombreux arbres. Ces arbres entravent les évaluations des stocks de poissons en compliquant l’échantillonnage acoustique et au filet maillant. Les arbres submergés peuvent facilement passer pour des bancs des poissons sur les échogrammes. Pour surmonter cette difficulté, nous avons mis au point une méthode permettant de distinguer les bancs de poissons des arbres submergés. Un algorithme de forêt aléatoire a été utilisé pour classer les écho-traces sur les échogrammes à 120 kHz et 200 kHz, enregistrées par un sondeur EK80 (SIMRAD) en modes à bande étroite (onde continue) et à large bande (modulé par la fréquence). Nous avons obtenu un bon taux de discrimination des arbres et des ...
Keywords	Text ; ddc:600 ; ddc:570
Language	English
Publishing country	de
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Estimates of variability of goldband snapper target strength and biomass in three fishing regions within the Northern Demersal Scalefish Fishery (Western Australia)

Gastauer, Sven / Ben Scoulding / Miles Parsons

Fisheries research. 2017 Sept., v. 193

2017

Abstract: Goldband snapper (Pristipomoides multidens) is an ecologically and economically important species in the Northern Demersal Scalefish Fishery (NDSF). The Carolina M, a trap fishing vessel operating in the NDSF, was equipped with Simrad ES70 echosounders, ... ...

Abstract	Goldband snapper (Pristipomoides multidens) is an ecologically and economically important species in the Northern Demersal Scalefish Fishery (NDSF). The Carolina M, a trap fishing vessel operating in the NDSF, was equipped with Simrad ES70 echosounders, operated at 38 and 120kHz. In 2014 acoustic data, in combination with optical recordings of the catch, were opportunistically collected during routine fishing operations. In December 2014 pure, low density goldband snapper schools were observed on the echograms. In situ target strength (TS) estimates were derived and linked to length distributions of catch information with the curve fitting method. Estimated TS-Length (L) at 38kHz was 20.1 log10(L)-70.5 and 16.4 log10(L)-77 at 120kHz. Three fishing grounds, where near simultaneously recorded acoustic and optical information was available were selected. Fish school densities observed within the 38kHz acoustic data were disaggregated according to catch proportions using kriging. Goldband snapper density estimates ranged between 9518 individuals per nmi2 in the high-density fishing region and 2512 and 945 individuals per nmi2 in the two low density fishing regions. Sampling variance was estimated using geostatistics (coefficient of variance, CV=10–20.9%). Other errors considered were signal-to-noise ratio (CV<1%), variation in the acoustic signal due to fluctuations in temperature and salinity (CV=0.5–1.15%), effects of diurnal vertical migration and variability of catch information (CV=1.2–2%). A total CV of 28.2–50.6% was estimated for all considered sources, for the three fishing regions.
Keywords	acoustics ; biomass ; fisheries ; fishery resources ; fishing boats ; geostatistics ; kriging ; migratory behavior ; Pristipomoides ; salinity ; schools of fish ; snapper ; temperature ; variance ; Western Australia
Language	English
Dates of publication	2017-09
Size	p. 250-262.
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	406532-3
ISSN	0165-7836
ISSN	0165-7836
DOI	10.1016/j.fishres.2017.05.001
Database	NAL-Catalogue (AGRICOLA)

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Article: Towards acoustic monitoring of a mixed demersal fishery based on commercial data: The case of the Northern Demersal Scalefish Fishery (Western Australia)

Gastauer, Sven / Ben Scoulding / Miles Parsons

Fisheries research. 2017 Nov., v. 195

2017

Abstract: Ongoing monitoring of complex, mixed species environments is a challenging task. In this study, the potential of acoustic and catch data collected aboard a commercial fishing vessel, in combination with geostatistical variance estimates, are explored as ... ...

Abstract	Ongoing monitoring of complex, mixed species environments is a challenging task. In this study, the potential of acoustic and catch data collected aboard a commercial fishing vessel, in combination with geostatistical variance estimates, are explored as a means to derive information on the distribution and abundance of key species groups within selected fishing regions. The FV Carolina M, a trap fishing vessel which operates in waters off Broome, Western Australia, in the Northern Demersal Scalefish Fishery, was equipped with Simrad ES70 echosounders, operated at 38 and 120kHz. Optical recordings of catch were also obtained, in addition to the acoustic data, during routine fishing operations in 2014. Three regions, where both optical and acoustic datasets were available, were selected for analysis. Geostatistical conditional simulations were used to combine acoustic density information with species composition proportions and length distributions within the catch. For each of the input datasets 250 simulations were conducted, from which individual and combined sampling CVs were derived. Conversion of acoustic densities into abundance estimates was achieved through application of target strength to length relationships (TS-L). Where TS-L was unavailable in the literature for a particular species it was estimated through a Kirchhoff-ray mode model. TS-L equations were estimated for rankin cod (Epinephelus multinotatus)(TSRC=20 log10(L)−79.6), triggerfish (Balistidae) (TSTF=20 log10(L)−77.7) and spangled emperor (Lethrinus nebulosus) (TSSE=20 log10(L)−70.8) at 38kHz. Sampling error was found to be generally low for catch proportions (<12%) and acoustic densities (<10%). Total sampling error CV for species group abundances within each of the three regions was 9%–38%, which is similar to typical estimates reported for acoustic surveys.
Keywords	acoustics ; Balistidae ; data collection ; Epinephelus ; equations ; fisheries ; fishing boats ; geostatistics ; Lethrinus nebulosus ; models ; monitoring ; species diversity ; surveys ; variance ; Western Australia
Language	English
Dates of publication	2017-11
Size	p. 91-104.
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	406532-3
ISSN	0165-7836
ISSN	0165-7836
DOI	10.1016/j.fishres.2017.07.008
Database	NAL-Catalogue (AGRICOLA)

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Article: In situ target strength measurement of the black triggerfish Melichthys niger and the ocean triggerfish Canthidermis sufflamen

Salvetat, Julie / Lebourges-Dhaussy, Anne / Travassos, Paulo / Gastauer, Sven / Roudaut, Gildas / Vargas, Gary / Bertrand, Arnaud

Marine & freshwater research. 2020, v. 71, no. 9

2020

Abstract: Triggerfish are widely distributed in tropical waters where they play an important ecological role. The black triggerfish Melichthys niger may be the dominant species around oceanic tropical islands, whereas pelagic triggerfish, such as the ocean ... ...

Abstract	Triggerfish are widely distributed in tropical waters where they play an important ecological role. The black triggerfish Melichthys niger may be the dominant species around oceanic tropical islands, whereas pelagic triggerfish, such as the ocean triggerfish Canthidermis sufflamen, can assemble around fish aggregating devices (FADs) where they are a common bycatch of tuna fisheries. In this study we combined acoustic and optical recordings to provide the first in situ target strength (TS) measurement of black and ocean triggerfish. Data were collected in the Archipelago of Fernando de Noronha off north-east Brazil. The mean TS of a 27.8-cm-long black triggerfish at 70 and 200kHz was –39.3dB re 1m2 (CV=14.0%) and –38.9dB re 1m2 (CV=14.4%) respectively. The mean TS values of ocean triggerfish (with a size range of 39–44cm) at 70 and 200kHz were –36.0dB re 1m2 (CV=15.7%) and –33.3dB re 1m2 (CV=14.0%) respectively. This work opens up the field for acoustic biomass estimates. In addition, we have shown that TS values for ocean triggerfish are within the same range as those of small tunas. Therefore, acoustic data transmitted from FADs equipped with echosounders can introduce a bias in tuna acoustic biomass estimation and lead to increased rates of bycatch.
Keywords	Canthidermis ; Melichthys niger ; Sufflamen ; acoustics ; aggregation behavior ; biomass ; bycatch ; dominant species ; islands ; tuna ; Brazil ; Fernando de Noronha
Language	English
Size	p. 1118-1127.
Publishing place	CSIRO Publishing
Document type	Article
ZDB-ID	1283028-8
ISSN	1323-1650
ISSN	1323-1650
DOI	10.1071/MF19153
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Krill biomass estimation

Bairstow, Fiona / Gastauer, Sven / Wotherspoon, Simon / Brown, C. Tom A. / Kawaguchi, So / Edwards, Tom / Cox, Martin J.

Sampling and measurement variability

2022

Abstract: Krill are the subject of growing commercial fisheries and therefore fisheries management is necessary to ensure long-term sustainability. Krill catch limits, set by Commission for the Conservation of Antarctic Marine Living Resources, are based on ... ...

Abstract	Krill are the subject of growing commercial fisheries and therefore fisheries management is necessary to ensure long-term sustainability. Krill catch limits, set by Commission for the Conservation of Antarctic Marine Living Resources, are based on absolute krill biomass, estimated from acoustic-trawl surveys. In this work, we develop a method for determining an error budget for acoustic-trawl surveys of krill which includes sampling and measurement variability. We use our error budget method to examine the sensitivity of biomass estimates to parameters in acoustic target strength (TS) models, length frequency distribution and length to wetmass relationships derived from net data. We determined that the average coefficient of variation (CV) of estimated biomass was 17.7% and the average CV due from scaling acoustic observations to biomass density was 5.3%. We found that a large proportion of the variability of biomass estimates is due to the krill orientation distribution, a parameter in the TS model. Orientation distributions with narrow standard deviations were found to emphasise the results of nulls in the TS to length relationship, which has to potential to lead to biologically implausible results.
Keywords	Text ; ddc:590 ; ddc:570 ; ddc:310 ; Antarctic krill -- biomass -- fisheries acoustics -- geostatistics -- target strength -- wetmass
Subject code	333
Language	English
Publishing country	de
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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