Relative benthic disturbances of conventional and novel otter boards

McHugh, Matthew J., Broadhurst, Matthew, Sterling, David, J., Millar, Russel, B., Skilleter, Greg and Kennelly, Steven, J. (2015) Relative benthic disturbances of conventional and novel otter boards. ICES Journal of Marine Science, 72 8: 2450-2456. doi:10.1093/icesjms/fsv100

Author McHugh, Matthew J.
Broadhurst, Matthew
Sterling, David, J.
Millar, Russel, B.
Skilleter, Greg
Kennelly, Steven, J.
Title Relative benthic disturbances of conventional and novel otter boards
Journal name ICES Journal of Marine Science   Check publisher's open access policy
ISSN 1095-9289
Publication date 2015-06-01
Year available 2015
Sub-type Article (original research)
DOI 10.1093/icesjms/fsv100
Open Access Status Not Open Access
Volume 72
Issue 8
Start page 2450
End page 2456
Total pages 7
Place of publication Oxford, United Kingdom
Publisher Oxford University Press
Collection year 2016
Language eng
Formatted 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.
Keyword Batwing
Hydrodynamic drag
Otter boards
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2016 Collection
School of Biological Sciences Publications
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Created: Fri, 04 Dec 2015, 18:40:51 EST by Gail Walter on behalf of School of Biological Sciences