Potential of electric fields to reduce bycatch of highly threatened sawfishes
Sawfishes are among the most threatened families of marine fishes and are susceptible to incidental capture in net fisheries. Since bycatch reduction devices currently used in trawl fisheries are not effective at reducing sawfish catches, new methods to minimise sawfish bycatch are needed. Ideally,...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Inter-Research
2021-10-01
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| Series: | Endangered Species Research |
| Online Access: | https://www.int-res.com/abstracts/esr/v46/p121-135/ |
| _version_ | 1818954524076802048 |
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| author | K Abrantes A Barnett M Soetaert PM Kyne A Laird L Squire J Seymour BE Wueringer J Sleeman C Huveneers |
| author_facet | K Abrantes A Barnett M Soetaert PM Kyne A Laird L Squire J Seymour BE Wueringer J Sleeman C Huveneers |
| author_sort | K Abrantes |
| collection | DOAJ |
| description | Sawfishes are among the most threatened families of marine fishes and are susceptible to incidental capture in net fisheries. Since bycatch reduction devices currently used in trawl fisheries are not effective at reducing sawfish catches, new methods to minimise sawfish bycatch are needed. Ideally, these should affect sawfish behaviour and prevent contact with the fishing gear. We tested the effects of electric fields on sawfish behaviour to assess the potential of electric pulses in mitigating sawfish bycatch. Experiments were conducted in a tank where 2 electrodes were suspended in the water column, connected to a pulse generator, and placed across the swimming path of sawfish. Two largetooth sawfish Pristis pristis were tested in control conditions, in the presence of a baseline pulse, and of 5 variations of that pulse where 1 parameter (polarity, voltage, frequency, pulse shape, pulse duration) was altered at a time. Conditional inference trees were used to identify the effects of various parameters (e.g. treatment, individual) on reaction type, reaction distance, twitching presence and duration, and inter-approach times. Sawfish reacted to electric fields, but reaction distances were small (typically <1.2 m), and no field tested consistently led to reactions conducive to escaping from moving nets. The following parameters induced the most response in both individuals: bipolar current, rectangular shaped, 5-10 Hz, ~1500 µs duration, and 100 V. We recommend further research focussing on moving nets, testing a V-shaped electric array preceding the net mouth by at least 5 m, and testing a setup similar to electrotrawling. |
| first_indexed | 2024-12-20T10:23:32Z |
| format | Article |
| id | doaj.art-89cd669998b54860a09010c64616b1a8 |
| institution | Directory Open Access Journal |
| issn | 1863-5407 1613-4796 |
| language | English |
| last_indexed | 2024-12-20T10:23:32Z |
| publishDate | 2021-10-01 |
| publisher | Inter-Research |
| record_format | Article |
| series | Endangered Species Research |
| spelling | doaj.art-89cd669998b54860a09010c64616b1a82022-12-21T19:43:52ZengInter-ResearchEndangered Species Research1863-54071613-47962021-10-014612113510.3354/esr01146Potential of electric fields to reduce bycatch of highly threatened sawfishesK Abrantes0A Barnett1M Soetaert2PM Kyne3A Laird4L Squire5J Seymour6BE Wueringer7J Sleeman8C Huveneers9College of Science and Engineering, James Cook University, Townsville, Qld 4811, AustraliaCollege of Science and Engineering, James Cook University, Townsville, Qld 4811, AustraliaInstitute for Agricultural and Fisheries Research, Animal Sciences - Fisheries, Ankerstraat 1, 8400 Oostende, BelgiumResearch Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0815, AustraliaNorthern Prawn Fishery Industry Pty Ltd, Caloundra, Qld 4551, AustraliaCairns Marine, Cairns, Qld 4870, AustraliaAustralian Institute of Tropical Health and Medicine, James Cook University, Cairns, Qld 4870, AustraliaSharks and Rays Australia, PO Box 575, Bungalow, Cairns, Qld 4870, AustraliaAustralian Institute of Tropical Health and Medicine, James Cook University, Cairns, Qld 4870, AustraliaCollege of Science and Engineering, Flinders University, Bedford Park, Adelaide, SA 5042, AustraliaSawfishes are among the most threatened families of marine fishes and are susceptible to incidental capture in net fisheries. Since bycatch reduction devices currently used in trawl fisheries are not effective at reducing sawfish catches, new methods to minimise sawfish bycatch are needed. Ideally, these should affect sawfish behaviour and prevent contact with the fishing gear. We tested the effects of electric fields on sawfish behaviour to assess the potential of electric pulses in mitigating sawfish bycatch. Experiments were conducted in a tank where 2 electrodes were suspended in the water column, connected to a pulse generator, and placed across the swimming path of sawfish. Two largetooth sawfish Pristis pristis were tested in control conditions, in the presence of a baseline pulse, and of 5 variations of that pulse where 1 parameter (polarity, voltage, frequency, pulse shape, pulse duration) was altered at a time. Conditional inference trees were used to identify the effects of various parameters (e.g. treatment, individual) on reaction type, reaction distance, twitching presence and duration, and inter-approach times. Sawfish reacted to electric fields, but reaction distances were small (typically <1.2 m), and no field tested consistently led to reactions conducive to escaping from moving nets. The following parameters induced the most response in both individuals: bipolar current, rectangular shaped, 5-10 Hz, ~1500 µs duration, and 100 V. We recommend further research focussing on moving nets, testing a V-shaped electric array preceding the net mouth by at least 5 m, and testing a setup similar to electrotrawling.https://www.int-res.com/abstracts/esr/v46/p121-135/ |
| spellingShingle | K Abrantes A Barnett M Soetaert PM Kyne A Laird L Squire J Seymour BE Wueringer J Sleeman C Huveneers Potential of electric fields to reduce bycatch of highly threatened sawfishes Endangered Species Research |
| title | Potential of electric fields to reduce bycatch of highly threatened sawfishes |
| title_full | Potential of electric fields to reduce bycatch of highly threatened sawfishes |
| title_fullStr | Potential of electric fields to reduce bycatch of highly threatened sawfishes |
| title_full_unstemmed | Potential of electric fields to reduce bycatch of highly threatened sawfishes |
| title_short | Potential of electric fields to reduce bycatch of highly threatened sawfishes |
| title_sort | potential of electric fields to reduce bycatch of highly threatened sawfishes |
| url | https://www.int-res.com/abstracts/esr/v46/p121-135/ |
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