Comparing three conventional penaeid-trawl otter boards and the new batwing design

  • Published source details McHugh M.J., Broadhurst M.K., Sterling D.J. & Millar R.B. (2015) Comparing three conventional penaeid-trawl otter boards and the new batwing design. Fisheries Research, 167, 180-189.


This study is summarised as evidence for the following.

Action Category

Modify the design or configuration of trawl doors

Action Link
Marine Fish Conservation
  1. Modify the design or configuration of trawl doors

    A replicated, paired, controlled study in 2013 in an area of seabed in the Clarence Estuary, New South Wales, Australia (McHugh et al. 2015) found that using a novel “batwing” design of otter boards on a shrimp trawl did not reduce the unwanted catch of four of four fish species or the overall discarded catch (fish and invertebrates), compared to three different conventional otter board designs. Average catch number of four of four unwanted fish species was similar between the batwing design and the three other conventional designs: forktail catfish Neoarius graeffei (batwing: 6.4, flat-rectangular: 7.7, kilofoil: 6.7, cambered: 5.6 fish), southern herring Herklotsichthys castelnaui (batwing: 2.7, flat-rectangular: 1.6, kilofoil: 1.1, cambered: 1.9 fish) mulloway Argyrosomus japonicas (batwing: 1.9, flat-rectangular: 1.8, kilofoil: 2.1, cambered: 1.7 fish) and yellowfin bream Acanthopagrus australis (date reported as model results). Average catch weight of all unwanted catch (fish and invertebrates combined) was similar with the batwing design (0.5 kg) compared to the flat-rectangular (0.4 kg), kilofoil (0.3 kg) and cambered board designs (0.4 kg). The batwing design comprised a sled and sail on a steel boom and mast (61 kg, 1.1 × 1.2 m) set to remain at a constant angle of 20° from the towing direction. The conventional designs were standard flat-rectangular boards (52 kg, 1.4 × 0.6 m), steel kilofoil boards with three vertical foils in a rectangular frame (63 kg, 1.3 × 0.6 m) and cambered boards with a single cambered foil over the boards length (53 kg, 1.1 × 0.7 m). Twenty-four 30-min paired trawl deployments (blocks of two door types towed from each side of the vessel) were performed with each board design on a 10 m trawler in depths of 4–18 m during May 2013 using a 41 mm mesh.

    (Summarised by: Leo Clarke)

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