Investigation on Early Development, the Feeding Ability and Larval Survival under Starvation in Common Meagre, Argyrosomus regius (Asso 1801)

Abstract

The development of Argyrosomus regius early development stages (embryonic, yolk sac and newly larval) was studied, with emphasis on yolk and lipid absorption. The effect of a progressively delayed initial feeding on the feeding ability and survival of this species was also examined. The number of days from hatching after which the feeding rate dropped to half the initial highest feeding rate or the point of no return (PNR) was determined. In May of 2010, the experimental eggs were obtained by natural spawning from captive broodstock (F1 generation cultured specimens). The embryo, yolk sac and larval stages of meagre were reared in laboratory conditions on temperature of 19°C and 35ppt salinity. Eggs present a diameter of 1.056±0.010mm, a volume of 0.616mm3 and a wet weight of 0.718±0.033mg, while they contain one lipid globule of 0.265±0.005mm diameter and 0.010mm3 volume. The total length of meagre larvae after hatching and at the onset of exogenous feeding was measured 2.621±0.037mm and 3.492±0.051mm, respectively. The yolk sac reserves were consumed 60h after hatching, while the reserves of oil globule exhausted 156h after hatching. The percentage of larvae with visible gut contents was maximal 108h after hatching and decreased to half (PNR) just 12h after this point or 120h after hatching. The findings indicate a high rate of food demand for this species.