CHANGES IN THE FATTY-ACID PROFILE OF THE AUSTRALIAN SHORTFIN EEL IN RELATION TO DEVELOPMENT

In glass eels (54 mm TL; 0.018 g) of the Australian shortfin eel Angui lla australis the fatty acid composition was typical of marine species , with a n-3 to n-6 ratio of 5.3, a low level of mono saturated fatty acids (monoenes) and a high level of polyunsaturated fatty acids (PUFA ). In elvers (pigmented: 56 mm TL; 0.028 g), the n-3 to n-6 ratio was 2.6. In elvers monoenes, as per cent of all identifiable fatty acids, increased to 30.9% from that of 19.8% in glass eels. The fatty acid co mposition of juvenile eels, reared from the original stock of glass ee ls and elvers, in outdoor, fertilized ponds, with (115 mm TL; 2.2 g) a nd without feeding(110 mm TL; 1.9 g), had a fatty acid composition typ ical of freshwater species, with a n-3 to n-6 ratio 1.9 and 1.3, and 3 7.7 and 46.5% of monoenes in unfed and fed groups respectively. A prin cipal component analysis summarized efficiently the progressive change s in fatty acid composition from the glass eel to juvenile eel stage. The observed changes in the fatty acid of the different developmental stages in Australian shortfin eel are discussed in relation to physiol ogical changes associated with the diadromous habit. (C) 1997 The Fish eries Society of the British Isles.