Reproductive management of the mugilid Liza aurata and characterization of proximate and fatty acid composition of broodstock tissues and spawnings

Abstract

The golden grey mullet (Liza aurata) is a promising species for aquaculture's sustainable expansion. However, the lack of sustainable juvenile provision, mainly related to the lack of reproductive control, is one of the most significant bottlenecks for further expanding the culture of this species. In many cases, mullet broodstock management needs the application of hormone treatments to induce gonadal maturation or spawning. However, no works are directly related to the broodstock collection, acclimation, and reproductive management of Liza aurata. On the other hand, the knowledge of essential fatty acids (EFA) requirements and mobilization patterns by the broodstock is a first step to designing appropriate feeding protocols and formulas, which are crucial for the success of reproduction and larval development. For these reasons, this study aimed 1) to describe for the first time the reproductive management of Liza aurata broodstock under controlled conditions and 2) to offer a first approach to the reproductive lipid metabolism of the former species. A selection of 22 Liza aurata broodstock from wild origin was acclimated in open seawater conditions. Additionally, the proximate and fatty acid composition of body tissues (gonads, liver, and muscle) of the initial wild population were evaluated, to be later compared with the profile of the eggs obtained after one year from the selected broodstock, for the first time described under cultured conditions. The results highlighted the feasibility for the obtention of natural spawnings from broodstock with a mean weight of 787 g and 604 g (females and males, respectively), at a sex ratio of 2:1 (females/males), under natural photoperiod and marine water conditions with temperatures decreasing from 20.4 ± 0.3 °C to 18.8 ± 0.4 °C. On the other hand, it was evidenced the crucial role of HUFA (highly unsaturated fatty acids) precursors for the gonadal development of Liza aurata, primarily for females. Additionally, the wild males' gonads presented a remarkable high content of HUFA, predominantly DHA (docosahexaenoic acid) (34% of the total fatty acids). In the eggs, significant variations appeared under captivity conditions, with lower levels of ARA (arachidonic acid) and EPA (eicosapentaenoic acid) and higher EPA/ARA and DHA/ARA ratios than the wild female gonad. Additionally, it was evidenced the significant role of the liver as a physiological reservoir of HUFA, which seem to be mobilized to the gonad during the maturation process. Present results may help obtain a better insight to adjust broodstock management conditions and feeds, contributing to a more sustainable aquaculture growth.