Variation in lipid composition of some deep-sea fish (Teleostei: Oreosomatidae and Trachichthyidae)

Abstract

The lipid, fatty acid and fatty alcohol compositions were determined for muscle samples from six species of deep-sea oreo collected from Australian waters; namely Neocyttus rhomboidalis, Neocyttus sp., Allocyttus verrucosus, Allocyttus niger, Pseudocyttus maculatus, and Oreosoma atlanticum. Neocyttus helgae, landed in North Atlantic waters, was also analysed. Similar analyses were also carried out on the muscle and swim bladder of the orange roughy Hoplostethus atlanticus from both Australian and North Atlantic waters. Orange roughy is currently a major commercial species in southern Australia and is a new-fishery in the North Atlantic; there are four species of oreo of increasing commercial significance in Australia due to orange roughy quota reductions. It is therefore necessary to determine if the oreo fishing industry is capable of supplementing the current orange roughy requirements with respect to muscle and oil demand. In the oreos, the mean lipid content ranged from 0.5 to 3% of wet weight, with a mixed lipid composition including wax ester, triacylglycerol, sterol and polar lipid. The ratio of the monounsaturated fatty alcohols 22:1 to 20:1 allowed samples from the two geographical regions to be distinguished. Total wax ester in muscle from North Atlantic male orange roughy was much higher than in Australian fish (27 vs. 8.5% wet weight, respectively); females from both locations contained similar amounts of wax ester (4.5 vs. 3.3%, respectively). Selected swim bladders from North Atlantic and Australian orange roughy show similar wax ester content (90 vs. 82%, respectively). The ratio of 22:1 to 20:1 fatty alcohols in orange roughy from the two regions was 0.5 (Australian) and 1.4 (North Atlantic). Indeed differences exist between oreos from the two locations, but not between orange roughy and this requires further investigation. With respect to the nutritional value, the oreos are more attractive than the orange roughy however lipid levels remain much lower compared with other popular species.