Relative benthic disturbances of conventional and novel otter boards

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dc.contributor.author McHugh, MJ en
dc.contributor.author Broadhurst, MK en
dc.contributor.author Sterling, DJ en
dc.contributor.author Millar, Russell en
dc.contributor.author Skilleter, G en
dc.contributor.author Kennelly, SJ en
dc.date.accessioned 2016-01-15T01:13:50Z en
dc.date.issued 2015-10 en
dc.identifier.citation ICES Journal of Marine Science: journal du conseil, 2015, 72 (8), pp. 2450 - 2456 en
dc.identifier.issn 1054-3139 en
dc.identifier.uri http://hdl.handle.net/2292/28001 en
dc.description.abstract Reducing otter-board angle of attack (AOA) has been proposed as a way to limit the habitat impacts of demersal trawls, but there are few quantitative assessments. This study tested the hypothesis that a novel otter-board design, termed the “batwing” (comprising a 0.1-m wide sled with an offset sail at 20° AOA) would have relatively fewer bottom impacts than a conventional flat-rectangular otter board (35° AOA, with a similar hydrodynamic spreading force). Pairs of each otter board were suspended beneath a purpose-built rig comprising a beam and posterior semi-pelagic collection net and repeatedly deployed across established trawl grounds in an Australian estuary. Compared with the conventional otter boards, the batwings displaced significantly fewer empty shells (Anadara trapezia and Spisula trigonella) by 89% and school prawns (Metapenaeus macleayi) by up to 78%. These rates were similar to the difference in base-plate bottom contact (87%). Further, the batwing damaged proportionally fewer damaged shells, attributed to their displacement away from the board's surface area. Other debris (lighter pieces of wood) and benthic fish (bridled gobies, Arenigobius bifrenatus) were not as greatly mobilised (i.e. reduced by 50 and 25%, respectively); possibly due to their position on or slightly off the bottom, and a similar influence of hydrodynamic displacement by the hydro-vane surface areas. Although the consequences of reducing otter-board bottom contact largely remain unknown, low AOA designs like the batwing may represent a practical option for fisheries where trawling is perceived to be hazardous to sensitive habitats. en
dc.description.uri http://icesjms.oxfordjournals.org/content/72/8/2450 en
dc.publisher Oxford University Press en
dc.relation.ispartofseries ICES Journal of Marine Science: journal du conseil en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.title Relative benthic disturbances of conventional and novel otter boards en
dc.type Journal Article en
dc.identifier.doi 10.1093/icesjms/fsv100 en
pubs.issue 8 en
pubs.begin-page 2450 en
pubs.volume 72 en
dc.rights.holder Copyright: Oxford University Press en
pubs.author-url http://icesjms.oxfordjournals.org/content/72/8/2450.full.pdf+html en
pubs.end-page 2456 en
dc.rights.accessrights http://purl.org/eprint/accessRights/RestrictedAccess en
pubs.subtype Article en
pubs.elements-id 515507 en
pubs.org-id Science en
pubs.org-id Statistics en
dc.identifier.eissn 1095-9289 en
pubs.record-created-at-source-date 2016-01-15 en


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