Efficiency of shrimp trawl nets polyamide and polyethylene with standard mesh in the coastal waters of Bushehr Province

This study was carried out in August – september 2009 in Bushehr province waters. Two different shrimp bottom trawls were used in which were woven by Poly Amid and Poly Ethylene with mesh sizes (stretched) of 50 mm and sack with 35 mm. Also 2 different vessels of two dhows and one steel ship each with 26 and 30 hauls were used and taken in to comparison from point of obtained results. Total catch of PA and PE trawels were 4592 and 5535 kg of which the ratio of shrimp catch and by catch for PA trawl was 32.4 and 67.6 % respectively; and for PE trawl was 34.2 and 65.8%. Total catch of PA and PE trawls of steel trawler ( ship ) were estimated 3158.0 and 4784.7 kg, respectively, of which the shrimp/ bycatch ratio was 6.6 : 93.4%. There was a higher amount of bycatch for PE comparing to PA trawl (p<0.05). on the other hand the decrease of shrimp and bycatch for PA comparing to PE dhow trawlers were 21.3 and 15.0% and for ship were 34.6 and 34.0% respectively. The weight ratio is 1:15 i.e . in PE ship trawl, in proportion to on kg shrimp, 15 kg bycatch was harvested. it is proposed to standardize the mesh size and also to do obligtory the instal of squared mesh size panel