Lipid and fatty acid composition of muscle, liver, ovary, and peritoneal fat in wild flathead grey mullet (Mugil cephalus) according to ovarian development

Abstract

Wild adult females of a low trophic omnivore teleost species, the flathead grey mullet (Mugil cephalus), caught in the western Mediterranean were sampled. The lipid and fatty acid composition of ovaries, liver, muscle, and peritoneal fat were analysed at previtellogenesis, early-vitellogenesis —first observed at mid-summer (early August)—, late-vitellogenesis, and the post-spawning period —from mid-September to mid-October—. During ovarian development, the lipid content of muscle was low and constant (3.85%–4.92%), indicating that the muscle was not used to store lipids for gonadal growth. Although constant, lipid content in the liver was higher (18.46%–22.62%) than in the muscle, and HSI% increased during gonad development, suggesting a dynamism in the mobilization of the hepatic lipids. Total lipids in the gonads significantly increased with maturation (from 4.90% to 34.59%) in parallel with the GSI (from 0.8% to 15.5%) to decrease after spawning. Peritoneal fat was probably transitional fat that could be rapidly metabolized or transferred to other tissues but no specific function could be assigned because its presence in previtellogenic and early-vitellogenic females varied greatly. One of the main sources of lipids accumulated in the ovary was most likely diet. The total percentage of ΣMUFA, mainly 17:1 —previously not identified in high quantities in teleost vitellogenic ovaries and likely of bacterial origin— and 16:1, strongly increased in the ovaries with maturation. The 16:1 might be an important source of lipids for embryo development. High percentages of DHA, EPA, and ARA were found in the ovary during previtellogenesis available to be used during gonadal maturation. Understanding lipid and fatty acid changes in broodstock tissues can increase our knowledge of the nutritional requirements of the fish used in aquaculture breeding programs.