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| Doray, Mathieu; Berger, Laurent; Le Bouffant, Naig; Coail, Jean-yves; Vacherot, Jean-philippe; De La Bernardie, Xavier; Moriniere, Pierre; Lys, Elisabeth; Schwab, Romain; Petitgas, Pierre. |
| Measuring fish target strength (TS) in the wild is challenging because: (i) TS varies versus physical (orientation relative to the incident sound wave, size, and depth) and physiological fish attributes (maturity and condition), (ii) the target species and its aforementioned attributes are difficult to assess in near real time, and (iii) in the case of packed fish schools, accepted echoes may originate from multiple unresolved targets. We propose a method for controlled TS measurements of densely packed small pelagic fish during daytime, based on the joint use of a Remotely Operated Towed Vehicle, “EROC”, with a pelagic trawl fitted with a codend opening system, “ENROL”. EROC, equipped with a 70-kHz split-beam echosounder (Simrad EK60) and a low-light... |
| Tipo: Text |
Palavras-chave: Acoustics; Deformed cylinder model; Engraulis encrasicolus; Remotely operated vehicle; Target strength; Video. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00346/45693/45623.pdf |
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| Demer, Da; Berger, Laurent; Bernasconi, M; Bethke, E; Boswell, K; Chu, D; Domokos, R; Dunford, A; Fassler, S; Gauthier, S; Hufnagle, Lt; Jech, Jm; Le Bouffant, Naig; Lebourges-dhaussy, Anne; Lurton, Xavier; Macaulay, Gj; Perrot, Yannick; Ryan, T; Parker-stetter, S; Stienessen, S; Weber, T; Williamson, N. |
| Acoustic instrument calibration is fundamental to the quantitative use of its data for estimating aquatic resource abundance. Regular calibrations also allow instrument performance to be monitored to detect changes due to the environment or component dynamics, degradation, or failure. This is the second ICES Cooperative Research Report (CRR) focussed on calibrations of acoustic instruments. The first, CRR No. 144 (Foote et al., 1987), was published during the era of analogue electronics more than a quarter of a century ago. Since then, not only has the acoustic equipment improved vastly with digital electronics and signal processing, but the techniques for applying them to studies of marine organisms have both advanced and diversified. Motivating,... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00586/69821/67711.pdf |
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| Bajjouk, Touria; Cordier, Celine; Auby, Isabelle; Liabot, Pierre-olivier; Kerninon, Fanny; Le Bouffant, Naig; Trut, Gilles; Oger-jeanneret, Helene. |
| Les phanérogames marines sont devenues ces dernières années des "espèces phares". Habitat à forte valeur écologique et patrimoniale, les herbiers bénéficient de mesures de gestion et de protection à différentes échelles : locale, nationale et internationale. Il y a donc un contexte favorable pour que les connaissances sur les herbiers progressent et que leur dynamique spatio-temporelle soit surveillée à une échelle globale. Depuis quelques années, et en lien avec les exigences des directives européennes, les phanérogames marines ont servi de support pour le développement et la valorisation des outils et techniques de télédétection pour la planification d'une gestion et d’une stratégie de surveillance efficace. En France, les méthodes pour évaluer les... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00514/62528/66891.pdf |
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| Blanluet, Arthur; Doray, Mathieu; Berger, Laurent; Romagnan, Jean-baptiste; Le Bouffant, Naig; Lehuta, Sigrid; Petitgas, Pierre. |
| Sound scattering layers (SSLs) are observed over a broad range of spatio-temporal scales and geographical areas. SSLs represent a large biomass, likely involved in the biological carbon pump and the structure of marine trophic webs. Yet, the taxonomic composition remains largely unknown for many SSLs. To investigate the challenges of SSL sampling, we performed a survey in a small study area in the Northern Bay of Biscay (France) by combining broadband and narrowband acoustics, net sampling, imagery and video recordings. In order to identify organisms contributing to the observed SSLs, we compared measured frequency spectra to forward predicted spectra derived from biological data. Furthermore, to assess the confidence in SSL characterization, we evaluated... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00588/70035/67955.pdf |
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| Doray, Mathieu; Coulon, Noémie; Huret, Martin; Le Bouffant, Naig; Berger, Laurent. |
| This study aims at estimating the anchovy biomass that was missed in the echosounder surface blind zone during the PELGAS survey, in an attempt to explain the relative difference between acoustic and DEPM biomass estimates in springtime 2019 in the Bay of Biscay. Acoustic data collected by a side-looking echosounder are analysed in order to estimate the negative bias introduced in acoustic biomass estimates by the acoustic blind zone. Corrected anchovy acoustic biomass estimates and maps are compared to DEPM ones, in an attempt to reconcile egg and acoustic estimates. Remaining discrepancies are discussed in the light of acoustic and egg biomass estimation assumptions. We showed that surface school biomass can be calculated while applying standard acoustic... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00662/77412/79072.pdf |
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| Dupre, Stephanie; Berger, Laurent; Le Bouffant, Naig; Scalabrin, Carla; Bourillet, Jean-francois. |
| Fishery acoustic surveys conducted in the Bay of Biscay and dedicated to monitoring and predicting pelagic ecosystem evolution reveal numerous active seeps on the Aquitaine Shelf, east of the shelf break, at water depths ranging from 140 to 185 m. Some acoustic anomalies recorded in the water column with hull-mounted single and multibeam echosounders are clearly caused by fluid escape at the seabed, most likely gases. These fluid emissions are associated at the seafloor with high backscatter subcircular small-scale mounds, on average less than 2 m high and a few metres in diameter. Based on near-bottom video and acoustic surveys, these mounds are interpreted to be by-products of gas seepage, possibly methane-derived authigenic carbonates. The spatial... |
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Palavras-chave: Bay of Biscay; Aquitaine Shelf; Parentis Basin; Fluid; Seepage; Acoustics. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00201/31192/29888.pdf |
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| Doray, Mathieu; Le Bouffant, Naig; Verin, Yves. |
| The Simrad ME70 multibeam echosounder has been operated in the Eastern Channel during the IBTS2010 sea survey (14-26/01/10). The objectives were: i) to observe dense night-time herring aggregations ii) to record ME70 data in fisheries research mode during demersal trawling to further test the interest of ME70-derived bathymetric indicators for demersal habitats characterisation iii) to acquire night-time acoustic data of sound scattering layers and compare them with synoptic mesopelagic trawls results i) to test the integration of a sidewards looking echosounder (Simrad ER60 120kHz, 2.5x10°) in the R/V acoustic data recording system. |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00068/17890/15420.pdf |
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| Le Bouffant, Naig; Berger, Laurent; Lurton, Xavier. |
| Bathymetric multibeam echosounders (MBES) classically improve their bottom detection resolution by increasing the number of beams with narrower beamwidths. Many independent detections are thus obtained when extracting one sounding in each beam. However when the pulse footprint on the bottom gets narrower than the beamwidth, which often happens at high incidence angles, it is possible to extract several independent bottom detections within the same beam. These high-density soundings extraction methods present a still higher interest for MBES designed with rather “wide” beams (say 3° or more), so as to offer other benefits, such as compacity, low-cost, or low sidelobe levels as for fishery applications. This paper presents a simple way to derive multiple... |
| Tipo: Text |
Palavras-chave: Multibeam; Bathymetry; Interferometry; Beamwidth. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00146/25719/23801.pdf |
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