FATTY ACID COMPOSITION OF SHARPHEAD DOGSHARK (SCOLIODON SORRAKOWAH)LIVER OIL DURING DEVELOPMENTAL STAGES

摘要

Fatty acid composition of the liver oil from different developmental stages of Sharphead dogshark( Scoliodon sorrakowah ) of the southern Fujian coastal waters, caught from May,1993 to April,1995,was determined with capillary gas chromatography. Saturated, monounsaturated and polyunsaturated fatty acids represented 15.3%～34.6% 13.8%～25.6% and 38.8%～68.1% of the total fatty acids in the liver oils of Sharphead dogshark, respectively. The major fatty acids in each sample were 16:0(79%～20.9%), 18:0(4.5%～12.1%),18:1ω9(6.1%～14.3%), 20:4ω6(2.8%～13.9%) and 22:6ω3(16.3%～56.2%). Characteristics of fatty acid composition of the liver oils in Sharphead dogshark was closely associated with the developmental stages of the animals examined. In male sharphead dogshark, 16:0(36.0%～39.8%), 16:1(17.1%～19.2%) and 18:1(ω9+ω7)(21.1%～23.1%) were the major constituents of fatty acids in the liver oils of embryos, the levels of 22:6ω3 (docosahexaenoic acids, DHA ) were very low (3.8±1.34, n =3). Concentrations of 22:6ω3 were much higher in the liver oils of immature males (27.1±2.47, n =3) than in that of embryos, and reached maximum values at prespawning stage (51.0±7.42, n =5) and then decreased significantly at regressed stage (34.4±2.40, n =3). Contents of 22:6ω3 in the liver oils in female increased during the development of the fish and reached maximun at the pre-gestation stage (49.7±4.04, n =5), which were significantly higher than that at the immature stage (25.7±0.64, n =3) and at ovary developing stage (33.3±3.46, n =4), respectively, and decreased remarkably at the end of gestation (25.6±8.08, n =3). It showed that DHA (22:6ω3) might play an important role in growth and development of Sharphead dogshark embryos.