Size selectivity of square and diamond mesh trawl codend for fish with different body shapes

摘要

Size selectivity of 40 mm square mesh 50 mm diamond mesh and 44 mm nominal diamond mesh codends were determined in terms of commercial situations in the east Mediterranean bottom trawl fishery to assess the size selectivity for red mullet (Mullus barbatus), goldband goatfish (Upeneus moluccensis), brushtooth lizardfish (Saurida undosquamis), common pandora (Pagellus e;ythrinus) and spotted flounder (Citharus linguatula). Data was achieved by the covered codend model and was analyzed with logistic equation by the maximum likelihood method. L-50 values for 44 mm diamond and 40 mm square mesh codends were 13.19 and 14.14 for M barbatus, respectively. 44 mm diamond codend appeared to have rather high L50 rate for U. moluccensis. A fairly high catch length was obtained with diamond mesh for P. erythrinus on account of its body shape. Square mesh codends were suitable for P. etythrinus. High escape rates and L-50 values were attained with all the three codends for S. undosquamis, which has the highest economic capacity in deep trawl fishing in the region. As to 50 mm diamond mesh codends, these seemed rather too wide meshes for these species.