Seasonal Variation in Highly Unsaturated Fatty Acid Composition of Muscle Tissue of Two Fishes Endemic to the Eastern Mediterranean

Abstract

Fatty acid content and profile in muscle tissue of two commercially important fishes from the Eastern Mediterranean were analyzed. One fish, Siganus rivulatus or rabbitfish, is an herbivore while the other fish, Diplodus sargus or white sea-bream, is a carnivore. Our aim was to evaluate changes in health benefits to consumers of said fishes among seasons and among species with different diets. Total fat content of the muscle in both fishes was low, being highest in August for the rabbitfish (3.31g per 100 g wet tissue) and in October for the white sea-bream (2.27 g per 100 g). Omega-3 and omega-6 highly unsaturated fatty acids (HUFA) as a proportion of total lipids also varied with season in both fishes. The total amount of lipid consumed per weight of tissue varied monthly among the species and one species is not necessarily better than another all year. However, on average, a person that consumes only rabbitfish throughout the year will eat more marine lipid than a consumer that eats only white sea-bream. Nonetheless, both species studied supply essential ω-3 and ω-6 HUFA. The ω-6:ω-3 ratio in fish in the present work was generally less than 2.0, but a diet that includes these fishes supplemented with some vegetable oil would raise the ratio to the recommended value of 4 to 6.

Keywords:

• rabbitfish
• white sea-bream
• omega-3 fatty acid
• HUFA
• seasonal variations

Acknowledgements

The authors would like to thank Dr. John Grover and Dr. Allen Davis for their help and advice in reviewing this article. We also thank the Lebanese National Council for scientific research and the American University of Beirut research board for their funding of the project.