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

journal contribution
posted on 2023-05-19, 12:46 authored by Hanamseth, R, Geoffrey BakerGeoffrey Baker, Sherwen, S, Mark HindellMark Hindell, Mary-Anne LeaMary-Anne Lea
  • 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 25 mm apart stretched tightly across a stainless steel frame that measured 1160 mm × 1540 mm 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.

    • History

    Publication title

    Aquatic Conservation

    Volume

    28

    Pagination

    175-181

    ISSN

    1052-7613

    Department/School

    Institute for Marine and Antarctic Studies

    Publisher

    John Wiley & Sons Ltd

    Place of publication

    The Atrium, Southern Gate, Chichester, England, W Sussex, Po19 8Sq

    Rights statement

    Copyright 2017 John Wiley & Sons, Ltd.

    Repository Status

    • Restricted

    Socio-economic Objectives

    Assessment and management of terrestrial ecosystems

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      University Of Tasmania

      Categories

      Keywords

      birdincidental mortalitynew techniquesoceanpenguinseabirdsensory perception

      Licence

      In Copyright

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