Standardization of mesh size in codend of the Miankaleh Beach Seine

Beach seine is fishing gears that occupy all depths of water from surface to bed by non-gillnet net. Increasing non-standard catches caused this survive was done to standardization of the beach seine mesh size. The research was started from winter of 2017 to spring of 2017, performing 73 hauling with four mesh sizes of 26, 28, 30 and 33 mm (knot to knot) in the bag area of ​​the beach seine in Miankaleh region of Golestan Province. According to the mesh size used in the bag section, the results showed that the highest amount of catches from different mesh size was done in size of 26 mm. Also, the maximum lengths were found for Liza aurata, Risso, 1810 in different mesh size in the 30-35 cm class length and for Alosa caspia, Linck, 1790 for 35-40 cm and for Rutilus kutum, Kamensky, 1901 at 30 to 35 cm. Also, in the mesh size of 26 mm, 50 percent of Lisa fish was caught at the length of 24.87 centimeters, in mesh size of 30 mm, 25.66 centimeters and mesh size of 32 mm, 26.65 centimeters. Also, the length of 50% of the permitted catch was obtained 25.5 centimeters by using 30 mm mesh size. According to the results, it was found that the Beach seines in the region did not caught selective and did catch much fish below the standard length.