Journal of the Persian Gulf (Marine Science)
Volume:3 Issue: 9, (Fall 2012

The spatial and temporal variations of finfish bycatch assemblage cutlassfish trawl were compared in two fishing areas (Hormozgan and Bushehr). Data were collected on board of commercial vessels in the fishing grounds of Trichiurus lepturus in Bushehr and Hormozgan marine waters between early May 2010 to late November, 2010. There was a significant difference in the bycatch assemblages between Bushehr and Hormozgan fishing grounds. SIMPER showed that six species contributed as much as 65% of the biomass of the bycatch assemblages between two fishing areas as follows: Nemipterus japonicus (30.5%), Ilisha melastoma (12.5%), Saurida tumbil (8.5%), Argyrops spinifer (6%), Dasyatis bennetti (4.5%) and Arius thalassinus (4%). Differences appeared for the temporal structures of bycatch assemblage in fishing grounds of Bushehr. SIMPER also showed eight species contributed to as much as 69.3% of 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%).

Copper (Cu) and mercury (Hg) enter aquatic ecosystems from different sources threatening health of aquatic organisms such as fish. As such, in this investigation, determinaing, Cu and Hg toxic concentration in Caspian roach (Rutilus rutilus caspicus), was undertaken. Acute toxicity of Cu and Hg were determined in fish specimen under semi-static condition. Caspian roach fry (~ 1 g) were exposed to Cu or Hg at 6 concentrations (0.2, 0.27, 0.39, 0.47, 0.59 and 0.66 mg L-1 total Cu and 0.22, 0.26, 0.3, 0.37, 0.44 and 0.52 mg L-1 Hg). Control fish were exposed to water with no Cu or Hg. Mortality was recorded at 24-h-intervals for 96 h. Total Cu-LC50 values found to be 0.43 mg L-1 for 24 and 48 h and 0.42 mg L-1 for 72 and 96 h. The lowest observed effect concentration (LOEC) values for total Cu were 0.39 mg L-1 for 24 and 48 h, and 0.20 mg L-1 for 72 and 96 h. On the other hand, free-Cu-LC50 values found to be 0.22 mg L-1 for 24 and 48 h and 0.21 mg L-1 for 72 and 96 h. LOEC values for free Cu were 0.20 mg L-1 for 24 and 48 h, and 0.10 mg L-1 for 72 and 96 h. 24-72 h LC50 values for Hg were 0.37 mg L-1, while 96 h LC50 found to be 0.33 mg L-1. Likewise, LOEC values for Hg were 0.26 mg L-1 for 24- 72 h, and 0.22 mg L-1 for 96 h. The results showed LOEC values for Cu and Hg in Caspian roach were lower than these metal concentrations in Caspian Sea water, suggesting little risk of acute toxicity in the sea. Chronic toxicity test is suggested to illustrate the effect of current levels of contamination in Caspian roach.

This study was conducted to evaluate the effect of different levels of dietary supplementation of Saccharomyces cerevisiae on growth performance, feed utilization and body biochemical composition of Oreochromis niloticus fingerlings. Four diets containing supplementation at levels of 0, 0.5, 1 and 2 g kg−1 were fed to fingerlings of Nile tilapia (5.01±0.21 g) in four replicate tanks twice daily to apparent satiation for 56 days. Growth performance increased significantly (P<0.05) with the increase in dietary yeast levels. The highest growth was obtained at 1.0–2.0 g yeast kg−1 diet. The lowest feed conversion ratio was obtained at 2.0 g yeast kg−1 diet. Linear relationship was found between dietary supplementation levels and protein efficiency ratio. Hepatosomatic index did not display any significant difference among the treatments. Whereas, Viscerosomatic index of O. niloticus fingerlings was significantly (P<0.05) affected by various supplementation levels. S. cerevisiae quantity significantly (P<0.05) affected whole fish body composition except for moisture and ash, which did not differ. The results of the present study indicated clearly that the supplementation of S. cerevisiae (1.0 g yeast kg−1 diet) enhanced the growth performance and feed utilization of O. niloticus fingerlings.

The present study was conducted to investigate the effects of cyclone Gonu on species diversity and abundance of gastropods in the Qeshm Island, northern Persian Gulf, on the occasion of the occurrence of super cyclonic and strongest reported storm- Gonu- during 1-4, June 2007 in the eastern Arabian Sea. Samples were collected before the Gonu storm (late May and early June 2007) and twice after the storm (July and August 2007 and March and April 2008). Average number of gastropod individuals per square meter was 7.85±1.42, 4.52±0.63, and 2.53±0.59 for rocky shores and 1±0.56, 0.11±0.06 and 4.26±3.96 for sandy shores, respectively. Both Shannon index and Buzas and Gibson''s evenness measure increased after the storm suggesting that Gonu affected diversity of gastropods of intertidal zone. Unlike result of cluster analysis that depicted two distinctive groups of assemblages over the sampling periods before and after the storm in rocky shore, the result of Kruskal-Wallis test yielded no significant difference (P>0.05) in gastropod abundance among sampling periods in two locations. Results of the present study suggested that gastropods abundance was not significantly (P>0.05) affected by cyclone Gonu while the species diversity was influenced.

The gastropod fauna of Bushehr Province intertidal zone at the Persian Gulf were identified following an investigation starting spring 2009 until winter 2011. Bushehr coastline is a 673.62 km stretch along the northern and northeastern coast of the Persian Gulf. Sampling took place from Deylam at Bushehr-Khuzestan borderlines, extending southeastward through Genaveh, Bushehr, Bolkheyr, Kabgan, Dayer and Nayband at Bushehr-Hormozgan provincial borderlines. A total of 87 gastropod species from 54 families were identified. The most frequent family with 7 spp. was Trochidae, followed by Strombidae (4 spp.), Pyramidellidae, Potamididae, Olividae and Epitoniidae (3 spp. each).The most frequent species was Planaxis sulcatus observed in all 7 stations, followed by Turitella fultoni, Thais mutabilis and Thais savignyi occurring in 6 stations. The Jaccard Similarity measure showed the highest similarity for Genaveh and Bushehr (0.818) and the lowest similarity for Genaveh and Deylam (0.152).This study provided the first comprehensive list of Gastropoda species occurring in Bushehr Province intertidal zones yet.

Multi-path interference due to boundary reflection in shallow water acoustic communication poses a major obstacle to reliable and high-speed underwater communication system. In this study, initially 3D variations of field data such as sound speed, temperature and salinity in horizontal transects of the Strait of Hormuz were analyzed using the ROPME data. Later, data on typical sound speed profiles of winter and summer of 1992 for the Strait of Hormuz was analyzed using ArcGIS software environment. Authors adopted a fast-field program to simulate the delay time and amplitude fluctuation of multipaths under different hydrographic conditions. Simulation results revealed the relationships between delay time and amplitude, and typical hydrographic parameters, such as sound speed gradient, travel distance and channel depth, which provided a valuable guide for the practical designing of shallowwater wireless acoustic communication system.

The Otolithes ruber is considered a valuable fish in the Indo-West Pacific. Estimates of the Q/B ratio and parameters of equations to ‘predict’ Q/B values for O. ruber in northwestern part of the Persian Gulf and the effects of different age-groups (age 1 to 6 year) on prey are presented. The age and food item of O. ruber were recorded on data collected from monthly samplings by bottom trawl during Oct 2007 to Sep 2008 and size frequency data were collected from commercial catches between Apr 2002 to Mar 2012. Food composition was analyzed by quantitative method. The effects of different age-groups on prey were calculated by biomass of the predator and the consumption rate of different age-groups. Six age group were identified. The biomass of stock was dominated by age-group 2 (3069 tons). Stomach contents of O. ruber included mostly shrimps and fish. Daily consumption of shrimp and all food items were 54 and 100 tons respectively. The highest and the lowest consumption rate and ratio of consumption to the stocked biomass were in age-groups 1 and 6, respectively. The Q/B ratios for shrimp and all food items were 3 and 5.57, respectively. Age-groups 2 and 3 had the most and age-group 6 the least effect on prey community. Shrimp consumption was greater during 2008-2009 than the minimum recorded in 2002-2003. Despite increasing biomass of O. ruber and increasing the consumption of shrimp, the shrimp catch was not much affected.