Image_1_Determination of Optimal Acoustic Passive Reflectors to Reduce Bycatch of Odontocetes in Gillnets.PDF
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 improvement of gillnet acoustic visibility, because these species...
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ftfrontimediafig:oai:figshare.com:article/12609746 2023-05-15T18:33:32+02:00 Image_1_Determination of Optimal Acoustic Passive Reflectors to Reduce Bycatch of Odontocetes in Gillnets.PDF Isabella M. F. Kratzer Ingo Schäfer Arne Stoltenberg Jérôme C. Chladek Lotte Kindt-Larsen Finn Larsen Daniel Stepputtis 2020-07-03T20:53:59Z https://doi.org/10.3389/fmars.2020.00539.s003 https://figshare.com/articles/figure/Image_1_Determination_of_Optimal_Acoustic_Passive_Reflectors_to_Reduce_Bycatch_of_Odontocetes_in_Gillnets_PDF/12609746 unknown doi:10.3389/fmars.2020.00539.s003 https://figshare.com/articles/figure/Image_1_Determination_of_Optimal_Acoustic_Passive_Reflectors_to_Reduce_Bycatch_of_Odontocetes_in_Gillnets_PDF/12609746 CC BY 4.0 CC-BY Oceanography Marine Biology Marine Geoscience Biological Oceanography Chemical Oceanography Physical Oceanography Marine Engineering bycatch odontocetes resonance target strength acrylic glass gillnet Image Figure 2020 ftfrontimediafig https://doi.org/10.3389/fmars.2020.00539.s003 2020-07-08T22:55:09Z 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 improvement of gillnet acoustic visibility, because these species use underwater sonar for orientation. Previous work on increasing gillnet detectability for echolocating animals by making the nets more recognizable has been based on trial and error, without understanding the fundamental acoustic properties of the tested modifications. Consequently, these studies have produced mixed and sometimes contradictory results. We systematically identified small, passive reflective objects that can improve the visibility of gillnets at a broad range of frequencies, i.e., for many odontocetes. We simulated the acoustic reflectivity of a wide range of materials in different shapes, sizes, and environmental conditions, with a focus on polymer materials. We verified the simulation results experimentally and calculated detection distances of the selected modifications. For example, if 8 mm acrylic glass spheres are attached to the net at intervals smaller than 0.5 m, the spheres have the same target strength (TS) at 130 kHz as the most recognizable part of a gillnet, the floatline. Modifications of the netting material itself, e.g., using barium sulfate additives, do not substantially increase the acoustic reflectivity of the net. Still Image toothed whales Frontiers: Figshare |
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Frontiers: Figshare |
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ftfrontimediafig |
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unknown |
topic |
Oceanography Marine Biology Marine Geoscience Biological Oceanography Chemical Oceanography Physical Oceanography Marine Engineering bycatch odontocetes resonance target strength acrylic glass gillnet |
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Oceanography Marine Biology Marine Geoscience Biological Oceanography Chemical Oceanography Physical Oceanography Marine Engineering bycatch odontocetes resonance target strength acrylic glass gillnet Isabella M. F. Kratzer Ingo Schäfer Arne Stoltenberg Jérôme C. Chladek Lotte Kindt-Larsen Finn Larsen Daniel Stepputtis Image_1_Determination of Optimal Acoustic Passive Reflectors to Reduce Bycatch of Odontocetes in Gillnets.PDF |
topic_facet |
Oceanography Marine Biology Marine Geoscience Biological Oceanography Chemical Oceanography Physical Oceanography Marine Engineering bycatch odontocetes resonance target strength acrylic glass gillnet |
description |
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 improvement of gillnet acoustic visibility, because these species use underwater sonar for orientation. Previous work on increasing gillnet detectability for echolocating animals by making the nets more recognizable has been based on trial and error, without understanding the fundamental acoustic properties of the tested modifications. Consequently, these studies have produced mixed and sometimes contradictory results. We systematically identified small, passive reflective objects that can improve the visibility of gillnets at a broad range of frequencies, i.e., for many odontocetes. We simulated the acoustic reflectivity of a wide range of materials in different shapes, sizes, and environmental conditions, with a focus on polymer materials. We verified the simulation results experimentally and calculated detection distances of the selected modifications. For example, if 8 mm acrylic glass spheres are attached to the net at intervals smaller than 0.5 m, the spheres have the same target strength (TS) at 130 kHz as the most recognizable part of a gillnet, the floatline. Modifications of the netting material itself, e.g., using barium sulfate additives, do not substantially increase the acoustic reflectivity of the net. |
format |
Still Image |
author |
Isabella M. F. Kratzer Ingo Schäfer Arne Stoltenberg Jérôme C. Chladek Lotte Kindt-Larsen Finn Larsen Daniel Stepputtis |
author_facet |
Isabella M. F. Kratzer Ingo Schäfer Arne Stoltenberg Jérôme C. Chladek Lotte Kindt-Larsen Finn Larsen Daniel Stepputtis |
author_sort |
Isabella M. F. Kratzer |
title |
Image_1_Determination of Optimal Acoustic Passive Reflectors to Reduce Bycatch of Odontocetes in Gillnets.PDF |
title_short |
Image_1_Determination of Optimal Acoustic Passive Reflectors to Reduce Bycatch of Odontocetes in Gillnets.PDF |
title_full |
Image_1_Determination of Optimal Acoustic Passive Reflectors to Reduce Bycatch of Odontocetes in Gillnets.PDF |
title_fullStr |
Image_1_Determination of Optimal Acoustic Passive Reflectors to Reduce Bycatch of Odontocetes in Gillnets.PDF |
title_full_unstemmed |
Image_1_Determination of Optimal Acoustic Passive Reflectors to Reduce Bycatch of Odontocetes in Gillnets.PDF |
title_sort |
image_1_determination of optimal acoustic passive reflectors to reduce bycatch of odontocetes in gillnets.pdf |
publishDate |
2020 |
url |
https://doi.org/10.3389/fmars.2020.00539.s003 https://figshare.com/articles/figure/Image_1_Determination_of_Optimal_Acoustic_Passive_Reflectors_to_Reduce_Bycatch_of_Odontocetes_in_Gillnets_PDF/12609746 |
genre |
toothed whales |
genre_facet |
toothed whales |
op_relation |
doi:10.3389/fmars.2020.00539.s003 https://figshare.com/articles/figure/Image_1_Determination_of_Optimal_Acoustic_Passive_Reflectors_to_Reduce_Bycatch_of_Odontocetes_in_Gillnets_PDF/12609746 |
op_rights |
CC BY 4.0 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.3389/fmars.2020.00539.s003 |
_version_ |
1766218158157332480 |