Relative efficiencies and durabilities of recreational hoop- and lift-nets targeting two Australian portunids

摘要

The temporal efficiencies and durabilities of established and alternative recreational portunid crab (Scylla serrata and Portunus pelagicus) baited nets were assessed during two experiments (simulating conventional and 'ghost' fishing) with the objective of minimising environmental impacts. The established gear ('hoop nets') comprised a circular panel of large, thin-twined mesh designed to entangle portunids while approaching a centrally located bait. The alternative gear ('lift net') had an identical diameter and central bait, but instead of entangling catches, comprised thicker, smaller meshes that were raised in a barrier during retrieval to prevent egress. Both gears similarly caught more portunids during nocturnal than diurnal deployments. When actively fished (i.e. retrieved every 30 min), lift nets were equally effective as hoop nets for catching S. serrata (and caused less exoskeleton damage mostly limb loss) and more than twice as effective for P. pelagicus (attributed in part to broader size selection). Lift nets were minimally damaged, but irrespective of the deployment duration, all hoop nets had broken/missing meshes (lost as marine debris), and those left for up to 12 days quickly became non-functional. The results illustrate the utility of simply substituting problematic gears instead of attempting their modification with those that are inherently more benign to reduce environmental impacts. Crown Copyright (C) 2016 Published by Elsevier B.V. All rights reserved.