Selectivity of sorting grid with horizontal bar for hake (Merluccius merluccius), red mullet (Mullus barbatus) and annular sea bream (Diplodus annularis)
Articles > Article · 2007
Authors: Celalettin Aydin, Adnan Tokac, Zafer TOSUNOĞLU
SU URUNLERI DERGISI, Journal Indexed in SCI Expanded, International, WoS, 2007, vol 24, pp 39-43
Summary
In this study, selectivity of sorting grid which has 35 mm horizontal bar spacing was investigated for hake (M. merluccius L., 1758), red mullet (M. barbatus L., 1758) and annular sea bream (D. annularis L., 1758). Experiments were carried out in the Izmir Bay, Aegean Sea in April 2003 with a traditional bottom trawl net (600 mesh around the mouth). Sorting grid was attached aft belly of the net. The fish totally retained in front of the grid and collected upper part, and escaped from the grid were used to estimate the selectivity. Selectivity data analyzed as covered cod end method by means of a logit function of Maximum Likelihood Method. The mean selectivity curves were estimated from the individual hauls which were fitted taking into account the between haul variation. The percentages of the total catch in terms of weight were 56 % retained and 44 % escaped. Mean L-50 value of hake, red mullet and annular sea bream were found as 24.7 cm +/- 1.7, 11.7 cm +/- 0.1 and 15.4 cm +/- 0.1, respectively. 35 mm horizontal bar spacing showed substantially higherL(50) value for hake regarding MLS compared to the mesh size and shape, and other vertical grid designs. However, this design shows over selectivity for annular sea bream and lower selectivity for red mullet.