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Assessing the importance of net colour as a seabird bycatch mitigation measure in gillnet fishing

Citation

Hanamseth, R and Baker, GB and Sherwin, S and Hindell, MA and Lea, MA, Assessing the importance of net colour as a seabird bycatch mitigation measure in gillnet fishing, Aquatic Conservation: Marine and Freshwater Ecosystems pp. 1-7. ISSN 1052-7613 (2017) [Refereed Article]

Copyright Statement

Copyright 2017 John Wiley & Sons, Ltd.

DOI: doi:10.1002/aqc.2805

Abstract

  • Gillnets are used widely in fisheries throughout the world and known to cause the death of thousands of seabirds each year. Currently few practical or technical options are available to fishers for preventing seabird mortalities.
  • The ability of little penguins (Eudyptula minor) to differentiate between different coloured netting materials was tested under controlled conditions to ascertain if changes in gillnet colour could facilitate a potential mitigation measure by improving visibility of nets.
  • The study involved a repeated-measures design with penguins exposed to variously coloured mono-filament threads creating a gillnet mimic. The gillnet mimic was made up of gillnet material configured as a series of vertical lines 25ámm apart stretched tightly across a stainless steel frame that measured 1160ámmáÎá1540ámm and divided into two equal panel areas. The panels were placed in a large tank within an enclosure that housed 25 penguins. Penguins were able to readily access the tank and swim freely. The frame was always introduced into the tank with one panel containing a gillnet mimic, and the other panel left empty as a control.
  • Gillnet filament colours tested were clear, green and orange. Orange coloured monofilament lines resulted in lower collision rates (5.5%), while clear and green monofilament lines resulted in higher rates of collision (35.9% and 30.8%, respectively).
  • These results suggest that orange-coloured lines were more apparent to the birds. Constructing nets of orange-coloured material may be effective in reducing bycatch in gillnets set in shallow waters and high light levels where seabirds are able to identify fine colour differences.
  • Further testing under experimental conditions, accompanied with at-sea trials to verify effectiveness in varied light conditions is warranted, together with an assessment of the effect of gillnet colour on catch efficiency of target species.
  • Item Details

    Item Type:Refereed Article
    Keywords:bird, incidental mortality, new techniques, ocean, penguin, seabird, sensory perception
    Research Division:Environmental Sciences
    Research Group:Environmental Science and Management
    Research Field:Wildlife and Habitat Management
    Objective Division:Environment
    Objective Group:Ecosystem Assessment and Management
    Objective Field:Ecosystem Assessment and Management of Marine Environments
    Author:Hanamseth, R (Mr Roshan Hanamseth)
    Author:Baker, GB (Dr Barry Baker)
    Author:Hindell, MA (Professor Mark Hindell)
    Author:Lea, MA (Associate Professor Mary-Anne Lea)
    ID Code:121852
    Year Published:2017
    Web of Science® Times Cited:2
    Deposited By:Centre for Ecology and Biodiversity
    Deposited On:2017-10-17
    Last Modified:2017-11-13
    Downloads:0

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