Feeding biology and biochemical composition of the lessepsian migrant Octopus aegina (Cephalopoda: Octopodidae)

The natural feeding of 609 Octopus aegina was studied in relation to the environmental seasonal variations in three populations in the Suez Canal, the Gulf of Suez and the Mediterranean Sea. Samples were collected seasonally from March 2009 till May 2010. Analysis of the stomach contents revealed that O. aegina attained the highest percentages of empty stomachs during spring for the three populations. The (1/2) full stomachs was dominant in the collected samples (32.97 %). The study revealed that 34.43 %, 32.83 % and 32.10 % of the examined stomachs were empty in the samples of Suez Canal, Gulf of Suez and Mediterranean, respectively. There was no definite seasonal food preference, and crustaceans were the most preferable food item followed by fishes. The biochemical composition of O. aegina revealed that females are higher than males in total protein content (72.41 % and 69.29 % for immature and mature females respectively) and total lipid content (38.4 g/100 g dry weight and 33.2 g/100 g dry weight for immature and mature females respectively). Amino acid analysis showed that O. aegina contains higher percentage of non essential amino acids (NEAA) than essential amino acids (EAA). Leucine, Lysine and Arginine had the highest percentage of EEA, while Asparagine, Glutamate and Glycine had the highest percentage of NEAA. EAA in males increased from 36.64% to 37.93 % in immature and mature respectively, while in females it increased from 36.93 % to 41.5 % in immature and mature respectively. Fatty acid analysis showed that males O. aegina contain higher percentage content of fatty acid components (SFA and UFA) than females. The results also revealed that SFA tended to decrease by maturation in males and females. Palmitic (16:0) and Stearic (18:0) were the most abundant SFA. Mature males had the highest percentage content of PUFA.