Search

This study was conducted to record best towing duration for bottom trawl surveys to stock assessment in the Persian Gulf. Shannon-Wiener, Margalef and evennes index were calculated for four towing duration (60, 90, 120 and 150minutes) in fishing grounds of Persian Gulf. A stratified random procedure was used for the survey sampling. The mean CPUA differed significantly with towing duration (P< 0.05) for the T. lepturus. The mean Shannon-Weiner diversity index differed significantly between four towing duration with higher Shannon- Weiner diversity index for 120minutes (2.81±0.44) (F=5.38; P=0.03. The mean CPUA differed significantly between towing durations with lowest CPUA at 150 minutes (P<0/05). Results showed that 120minutes towing duration was the best for scientific surveys. 150 minutes towing duration was not suitable for scientific surveys in the Persian Gulf. The present research provided the first comprehensive study on the effect of trawl duration on diversity index and CPUA in Persian Gulf. [ABSTRACT FROM AUTHOR]

The spatial and temporal variations of finfish bycatch assemblages cutlassfish trawl were compered in two fishing area (Hormozgan and Bushehr waters). Data were collected on board of commercial vessels in the fishing grounds of Trichiurus lepturus since May 1st 2009 to November 2010. There was a significant difference in the bycatch assemblages between Bushehr and Hormozgan fishing grounds. SIMPER showed that six species contributed 65% of the biomass of the bycatch assemblages between two fishing areas: Nemipterus japonicus (30.5%), Ilisha melastoma (12.5%), Saurida tumbil (8.5%), Argyrops spinifer (6%), Dasyatis bennetti (4.5%) and Netoma thalassinus (4%). Differences appeared for the temporal structures of bycatch assemblages in fishing grounds of Bushehr. SIMPER showed that eight species contributed 69.3% to the dissimilarity of the biomass of the bycatch assemblages between fishing seasons. These species were S. tumbil (17.3%), I. melastoma (16.3%), N. japonicus (13.3%), Carangoides malabaricus (17.2%), Rachycentron canadun (6.3%), Upeneus sundaicus (3.5%) D. bennetti (3.5%) and Epinephelus coioides (3.2%). [ABSTRACT FROM AUTHOR]