Population structure of two Octopus species, Amphioctopus aegina and A. membranaceus in the Gulf of Suez, Egypt.

Ahmed Et Al., Ayman S.

doi:10.21608/ejabf.2023.330203

Population structure of two Octopus species, Amphioctopus aegina and A. membranaceus in the Gulf of Suez, Egypt.

Document Type : Original Article

Author

Ayman S. Ahmed et al.

10.21608/ejabf.2023.330203

Abstract

Ageing of Amphioctopus. aegina and A. membranaceus revealed three different age groups, and the main bulk of the catch was represented in the second age group for the two species. Von Bertalanffy growth constants were determined as; L_∞= 11.76 cm DML, K= 0.39 year^-1, t₀= 0.11 year^-1 and Ø= 1.73 for A. aegina, and L_∞= 11.47 cm DML, K= 0.45 year^-1, t₀= 0.33 year^-1 and Ø= 1.77 for A. membranaceus. The total mortality (Z), natural mortality (M), fishing mortality (F) and exploitation rate (E) were calculated as 2.87, 1.17, 1.70 and 0.59 year^-1, respectively for A. aegina, and 2.70, 1.29, 1.41 and 0.52 year^-1, respectively for A. membranaceus. The length at recruitment (L_r) of A. aegina and A. membranaceus was 1.9 and 2.4 cm DML, that corresponding to age (t_r) of 0.56 and 0.85 year, respectively. Length at first capture (L_c) was 6.28 and 4.05 cm DML for A. aegina and A. membranaceus, respectively, and the age at the first capture (t_c) was 2.07 and 1.46 years, respectively. This study is very important for fisheries management in the Gulf of Suez, where, some recommendations to reduce the exploitation rates for the two Octopus species in the Gulf were proposed.

Keywords