Biological aspects of Sepia pharaonis in the Bahrekan waters (NW Persian Gulf)

The biological aspects of Sepia pharaonis was studied during years 2006-07. The studied area restricted to the Bahrekan in khouzestan province covering the depths of 2 up to 25m. The sampling methods were gillnet and bottom trawl. A total of 310 specimens collected, of which there wasn t found any cuttlefish in the study area from July to October (5 months). The collected samples were transferred to the labortatory ashore for further biological measurements consist of: Mantle length, Body weight, sex determination. Gonado-Somatic Index, and determination of Spermatophoric Index, Spawning season, Food preference, Maturity stages and chemical analysis for food value determination. The results showed that the overall sex ratio is about M:F= 2:1 with percentage of 67.41% for males and 32.50% for females. Males are significantly bigger than females with average mantle length (ML) of 233.3 and 269.3 mm for female and male, respectively; with body weight of 1102.3 and 1450.6 g. The mantle length body weight relationship was found W=0.001 ML 2.540 (R2= 0.92) Female as: W= 0.0015 ML 4797 (R2= 0.93) male From point of feeding, the food preferences results indicated that fish is considered as main food, crabs as minor food and other marine organisms such as bivalvia and gastropods as random food. The highest vacuity Index (CV) and empty stomachs was determined for March-April and the lowest value was is December. Also, the maximum GSI was estimated for March-April months in which showing coherrances with the lowest food preference. The maximum spermatophoricfilaments were 856 and 45 for male pharaoh cuttlefish with mantle length of 300 and 185 mm, and on the other hand this values for fecundity were estimated 1589 and 53 for female specimens with 254 and 198 mm mantle length. The spawning season occurs in April- March in which accompany with migration of pharaoh cuttlefish towards shallow waters. The fishing season would be in this period in which needs management approaches.