Lipid and fatty acid composition of pre- and post-spawning blacklip ( Haliotis rubra) and greenlip ( Haliotis laevigata) abalone conditioned at two temperatures on a formulated feed

Abstract

Wild-caught blacklip ( Haliotis rubra) and greenlip ( Haliotis laevigata) abalone fed a formulated feed were held from spent to gravid condition at 14 or 18 °C. Half the gravid animals were induced to spawn (using heated UV-irradiated seawater) and the remainder left untreated. All animals were then killed and samples of foot, digestive gland (DG) and gonad analyzed for lipid and fatty acid (FA) composition, as was the feed. The feed contained 5% lipid, of which the major FA were 18:2n−6 (27%), 18:1n−9 (20%) and 16:0 (16%). The lipid content of each tissue was similar for both species, ranging from 4–6%, 8–9%, 14–15%, and 30–32% in the foot, testis, DG and ovary, respectively. Each tissue had a different FA signature, with the foot, testis and ovary characterized by elevated levels of 20:4n−6 (arachidonic acid-ARA), 20:5n−3 (eicosapentaenoic acid-EPA) and 18:2n−6 (linoleic acid-LA), respectively. The proportions of LA and EPA in the DG were intermediate between those of the testis and ovary. There was no change in the lipid or fatty acid composition of blacklip or greenlip tissues in response to the two culture temperatures. Likewise, these compositions did not appear to differ between tissues from spent and gravid individuals. Tissue FA profiles from abalone fed a formulated feed are compared to those from macroalgal feeding trials to determine if the formulated feed can be further improved.