The purpose of this study was to investigate the effect of voltage, salinity and temperature on the performance of electric fishing. To do so, 850 pcs Gambosia holbrooki from Golestan dam were hunted and transported to the laboratory. Distance from the anode, cathode and anode distance during testing were 10cm and 120cm, respectively. Experimental fish length and weight range for this species were calculated 3.818 ± 0.20 cm and 0.804 ± 0.135 gr , respectively. Electric shocks were applied to individual fish in three voltages of 15, 45 and 135 volts and 3 °c, 10 °c, 20 °c and 30 °c, and 3 salinity of 0.5, 2 and 4 g/l. Time to pass out and return to the initial state for individual fish were recorded. Statistical analysis of ANOVA, Duncan and LSD showed that the average duration of voltages and temperatures and salinities of anesthesia obtained are significantly different. The maximum and minimum anesthesia time were calculated for the Gambosia holbrooki from the salinity of 0.5, 10° c, Voltage 15, with a mean of 8.71 ± 0.74s and from the salinity of 4, 30° c, Voltage 135, with a mean of 1.44 ± 0.32s, respectively. The maximum and minimum reset time for Gambvzya were resulted from the salinity 0.5, 10° c, Voltage 135, with a mean of 94.84 ± 3.1s and the salinity of 0.5, 30° c, Voltage 15, with a mean of 20.01 ± 2.72 s, respectively.

In this study 865 specimen of L. aurata was collected from different stations of south western coasts of the Caspian Sea (Guilan) including Anzali, Astara and Roudsar July 2014 to September 2015. Sampling of the Fishes were by beach seine of various mesh size (33, 20, 30mm). Difference in length and weight among locations were investigated. The average weight, fork length and age of the specimens were 33.33±6.89, 453.47±346/88 and 6.7±2.3633. The length¬ weight relationship for this population was calculated as W= 0.0292×FL^2.716. Growth parameters were estimated as were estimated L∞=54.33 cm, K =0 .13 yr^-1, and t0=-1.51.  Population growth pattern was negativeive allometric (b=2.71) The natural and fishing mortality were 0.56 ,.182and 0.37year-1respectively  and exploitation ratio was 0.67 yr^-1.