Dietary lipid enhancement of broodstock reproductive performance and egg and larval quality in Atlantic halibut (Hippoglossus hippoglossus)

Two series of experiments were conducted to assess whether the trash fish-based diet traditionally used by the industry for broodstock halibut could be replaced by a formulated pelleted feed and to investigate the effects of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (AA) on halibut fecundity, blastomere morphology and fertilisation and hatching rates. In the first experiment, two formulated broodstock feeds (one containing Krill meal and one supplemented With tuna orbital oil, which provided higher dietary levels of DHA and AA), gave similar performances (Relative fecundity 9557 +/- 3462 and 10,551 +/- 2166, fertilisation rate 40.0 +/- 6.4% and 40.0 +/- 9.1%, respectively) to that of a fish fed a trash fish-based diet (Relative fecundity 11,782 +/- 1873, fertilisation rate 41.0 +/- 4.0%). In a second experiment, the spawning performance and egg quality of two groups of broodstock maintained on two formulated diets, each containing different levels of AA (1.8% and 0.4%) was compared over two successive spawning seasons. The diet with the higher (1.8%) level of AA resulted in significantly higher (p<0.05) fertilisation rates (59.0 +/- 5.8%), blastomere morphology scores (14.2 +/- 0.4) and hatching rates (51.0 +/- 3.6%) compared to those on the 0.4% AA diet (31.0 +/- 4.9%, 12.5 +/- 0.3 and 28.0 +/- 5.7%, respectively). The eggs selectively accumulated DHA up to 30% of the total fatty acids. DHA/EPA and EPA/AA ratios of 2 and 4 in the eggs respectively were associated with improved egg and larval quality, similar to that achieved by fish maintained on the trash fish-based diets. (C) 2003 Elsevier B.V. All rights reserved.