Introduction: The Pharaoh Cuttlefish (A. pharaonis), due to its high commercial and export value, is harvested in the Persian Gulf and the Oman Sea using various fishing gears, including trawl nets, traps (Gargoor), and gillnets. Although comprehensive stock assessments are lacking, available evidence suggests that this species is under increasing fishing pressure in the region. This study aimed to investigate the growth and mortality parameters of A. pharaonis based on age-based models in the waters of Hormozgan Province. The findings can inform fisheries managers in developing effective conservation and exploitation strategies for this valuable stock.
Materials and Methods: A total of 109 specimens (76 males and 33 females) were collected from Bandar Lengeh, Qeshm, and Bandar Abbas between October 2023 and March 2024 using trap and small-scale trawl fishing methods. In the laboratory, the morphometric features of the specimens were measured. The specimens were dissected to extract cuttlebones and prepared for age reading. Age was determined through a standardized three-step reading process under a dissecting microscope. Growth parameters (L∞ and k) were estimated for both sexes using the Gulland and Holt method. Total mortality (Z) and natural mortality (M) were calculated using a catch curve and the Chen and Watanabe age-based mortality model, respectively.
Results: Mantle length ranged from 62 to 330 mm in males (mean ± SD: 135.4 ± 67.1 mm) and from 57 to 300 mm in females (mean ± SD: 104.4 ± 54.2 mm). The von Bertalanffy growth models for mantle length-at-age Lt(mm) = 342[1 – exp (-0.27(t - 0.00))] for Males and Lt(mm) = 316[1 – exp (-0.30(t - 0.00))] for Females. The difference in growth models between sexes was statistically significant (Likelihood Ratio Test, p < 0.05). Estimated mortality rates for males were Z=3.14 yea r-¹, M = 1.73 year-¹, F= 2.73 year-¹, and for females Z= 4.46 year-¹, M= 1.79 year-1, and F= 2.35 year-¹. The exploitation rates (E) were also estimated at 0.61 for males and 0.43 for females.
Discussion: The findings indicate a rising trend in fishing mortality for A. pharaonis in the Persian Gulf compared to earlier studies. Given the overlap between the species' spawning season and peak fishing activity, continued high exploitation may pose a serious risk to stock sustainability. Therefore, it is recommended that fishing efforts and gear types targeting this species be regularly monitored. Establishing a robust database could support stock modeling and provide forecasts to guide adaptive fisheries management.
Discussion: The findings indicate a rising trend in fishing mortality for A. pharaonis in the Persian Gulf compared to earlier studies. Given the overlap between the species' spawning season and peak fishing activity, continued high exploitation may pose a serious risk to stock sustainability. Therefore, it is recommended that fishing efforts and gear types targeting this species be regularly monitored. Establishing a robust database could support stock modeling and provide forecasts to guide adaptive fisheries management.arlier studies. Given the overlap between the species' spawning season and peak fishing activity, continued high exploitation may pose a serious risk to stock sustainability. Therefore, it is recommended that fishing efforts and gear types targeting this species be regularly monitored. Establishing a robust database could support stock modeling and provide forecasts to guide adaptive fisheries management.