Growth study of Giant cuttlefish (Sepia ‎pharaonis) during spawning period in the ‎northern Persian Gulf

Growth parameters of cuttlefish (Sepia pharaonis) was estimated from northern Persian Gulf, (27˚ 50´ 06˝ and 30˚ 06´ 07˝N to 52˚ 02´ 56˝and 50˚ 05´ 14˝E) from October 2017 to May 2018. 100 to 150 specimens were randomly separated each time from total catch and mantel length and body weight were measured by sexes. Based on the Von-Bertalanffy growth formula in males, growth parameters were estimated with K=0.3 year-1 and L∞=37 cm. In females, growth coefficient, K and asymptotic length, L∞ were estimated 0.5 year−1 and 30 cm respectively. Maximum of fishing effort was observed in November 1.08±0.71 kg per trap and minimum was 0.06±0.02 kg per trap in May. Maximum catch per trap was 0.65±0.56 kg in 21-30 m depths and minimum was 0.10±0.05 kg in 41-50 m depths. Low growth coefficients in males and females show that this species reached to maximum growth during presence in the study area. Also, its aggregation in the depths of 30-21 m indicates the accumulation of mature spawning specimens in the area, which needs serious protection.