Broadhurst et al,: Use and success of square-mesh codends in reducing bycatch and improving size-selectivity of prawns 



437 



120 T 



81 N 



100 T 



100 T 



24 strand, 

 45 mm mesh 



55 B 



ION 



61 B 



ION 



B 



120 T 



62 B 



^#— 



62 8 



100 T 



62 B 



6B~ 



13B 



62 B 



100 T 



48 ply, 45 mm 

 mesh 



-1 



36 ply, 52 mm 

 mesh on the bar 



-"^fe^ 



48 ply, 45 mm 

 mesh 



36 ply, 52 mm 

 mesh on the bar 



3 mm braided, 



85 mm mesh 



on the bar 



T 



23 B 



i 



37 B 



.48 ply, 45 mm_ 

 mesh 



-g 



120 T 



120 T 



70 B 



62 B 



.^ 62 B 



68 



138 



588 



58T 



79 8 



T 

 5N 



61 B 



W-^ 



2N 



1 



Lastridge ropes 

 (PE0 12 mm 



Figure 3 



Diagrammatic representation of lAi the control codend. (B) coniposite-square-2 codend, and 

 (C) composite-square-3 codend. T = transversals; N = normals; and B = bars. 



rior diamond-mesh section was used to attach the 

 codend lifting rope (termed "lazy-Hne"), whereas the 

 posterior diamond-mesh section was used to attach 

 the draw-string of the codend. 



The composite-square-3 codend comprised an an- 

 terior square-mesh section 79 bars in length attached 

 to a posterior square-mesh section 61 bars in length 

 (Fig. 3Cl. The circumference of this codend tapered 

 from 70 bars at the start of the anterior section to 58 

 bars at the end of posterior section. Two diamond-mesh 

 sections (400/48 ply mesh size, UV-stabilized, high-den- 

 sity polyethylene twine), 2 meshes in length were at- 

 tached immediately anterior and posterior (hanging 

 ratio of 0.57) to the two square-mesh sections ( Fig. 3C). 

 The anterior diamond-mesh section measured 120 

 meshes in circumference, whereas the posterior dia- 

 mond-mesh section measured 58 meshes in circumfer- 



ence and had the codend draw-string attached. Two 

 4.5-m lengths of 12-mm diameter, 3-strand polyethyl- 

 ene rope (termed "lastridge ropes") were firmly laced 

 at a hanging ratio of approx. 0.9 to each of the two seams 

 of the composite-square-3 codend to provide additional 

 lengthwise strength to the entire codend. The poste- 

 rior ends of the lastridge ropes extended past the codend 

 and were secured together during each tow. 



Sampling protocol and data collected 



The two composite square-mesh codends were sepa- 

 rately compared against the control codend. In each 

 paired comparison, the control and composite square- 

 mesh codend being tested were zipped to each out- 

 side trawl of the triple-rigged gear and towed simul- 

 taneously. The codends were used in normal com- 



