Differences in lipid class and fatty acid composition between wild and cultured sea cucumbers, Apostichopus japonicus, explain modification and deposition of lipids

The Japanese sea cucumber Apostichopus japonicus, a commercial species highly valued for its medicinal and nutritious properties, is wild‐harvested cultured in the countries of the North Pacific region. To assess the modification and deposition of dietary lipids in tissues of A. japonicus, the compositions of lipid classes and fatty acids (FAs) in the body wall and alimentary canal were compared between wild and cultured specimens. The results show that dietary lipids are rich in iso/anteiso saturated FAs (SFAs), monounsaturated FAs (MUFAs; mainly, 18:1n‐9 and 18:1n‐7) and linoleic acid (18:2n‐6). A deficiency in dietary polyunsaturated FAs (PUFAs) considerably reduces the total and storage lipids in the alimentary canal, modifies the FA composition of both tissues, and increases the difference in the FA profile between the body wall and alimentary canal. Cultured specimens have trace amounts of 16:1n‐7, a considerably higher level of 20:4n‐6 and a lower level of 20:5n‐3 compared with those recorded from wild animals. A suggestion is made that dietary SFAs are not deposited, whereas dietary C16 PUFAs and 20:5n‐3 are accumulated. Dietary C16‐18 MUFAs are rapidly elongated into C22‐24 MUFAs, and dietary 18:2n‐6 is converted into 20:4n‐6. Knowledge of these patterns may facilitate a choice between available diets to optimize the lipid profile of cultured sea cucumbers.