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The fatty acid profiles of neutral and polar lipids were analysed in tissues of muscle, liver and skull oil of the deep-sea redfish Sebastes mentella caught over the Reykjanes Ridge. The fatty acid compositions of both the neutral and the polar lipid fractions were tissue specific. The high amounts of the phytoplankton-derived fatty acids, 20:5n3 and 22:6n3, in the neutral fractions of the muscle tissues clearly distinguished the muscle lipids from liver lipids and skull oil. In the skull oil, the fatty acid profiles of the neutral lipids were characterized by extremely high amounts of the long-chained mono-unsaturated fatty acids, 22:1n1, 20:1n9 and 18:1n9, indicating selective enrichment of these fatty acids. Of the tissues studied here, the neutral fraction of the muscle best reflects diet, while the skull oil is believed to be unsuitable in trophic studies. Interestingly, in the muscle oil, there were high amounts of docosahexaenoic acid, 22:6n3 (23%). Docosahexaenoic acid is a unique fatty acid important in the cell membrane, and the levels found in S. mentella are similar to those found in other deep-living fish species.

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Pálsson, Ó. K., Gislason, A., Guðfinnsson,  H. G., Gunnarsson, B., Ólafsdóttir, S. R., Petursdottir, H., Sveinbjörnsson, S., Thorisson, K., and Valdimarsson, H. 2012. Ecosystem structure in the Iceland Sea and recent changes to the capelin (Mallotus villosus) population. – ICES Journal of Marine Science, 69: . The objective of the Iceland Sea Ecosystem Project was to analyse principal ecosystem patterns, including the life history of capelin. Ten surveys were conducted for this purpose between 2006 and 2008, and hydrographic data from 1970 to 2011 were analysed. Long-term temporal patterns indicate an increase in the temperature of surface and intermediate waters during recent years in the Iceland Sea. The phytoplankton consisted mainly of diatoms in spring, with flagellates and dinoflagellates appearing later in the year. Zooplankton and fish were dominated by a few species. In late summer, the pelagic foodweb ranged between trophic levels 2.4 and 3.6. Trends in nutrients and primary production showed a clear seasonal pattern with a spring bloom in late May, followed by a peak in secondary production in July/August. The spatial structure of the lower ecosystem levels in summer was stable across the 3 years, determined mainly by the structure of the water masses. The pelagic fish fauna consisted primarily of adult pelagic fish and transient numbers of larval species. The spatial pattern of capelin indicated northward displacement of 0-group capelin and westward displacement of older capelin in recent years. The annual biomass was estimated at 3.8 million tonnes of phytoplankton, ∼21 million tonnes of zooplankton, and 1.0 million tonnes of fish.