T45 side panels improve penaeid-trawl selection

The utility of fitting panels of mesh turned 45° ('T45' or 'square-shaped' mesh) in a generic penaeid trawl body was investigated for improving selectivity. Compared to a conventional trawl comprising 43-mm diamond-shaped mesh throughout the body and a codend made from 27-mm T45 mesh, replacing just the side panels (18% of the total trawl area) with those made from 32- and 35-mm T45 mesh generally improved size-selection for school prawns, Metapenaeus macleayi-which was the dominant species-and especially in the trawl with 35-mm T45 mesh. This trawl also had a trend of improved size selection for the much less abundant eastern king prawns, Penaeus plebejus. Commercial catches of both penaeids were not negatively affected by the modifications. No teleosts were significantly affected by T45 side panels-although the predicted mean numbers of species with individuals smaller than the 32- and 35-mm T45 meshes were slightly lower. We conclude that retroactively inserting T45 side panels with an appropriate mesh size into penaeid-trawl bodies could be a simple and effective strategy for improving size selection; either as an adjunct to T45 codends, or as an alternative modification.