Consumo de oxígeno, crecimiento y utilización del alimento durante el desarrollo larval del besugo Pagrus pagrus (Linné, 1758) (Pisces: Sparidae)

Abstract

Knowledge of the life history of fish larvae is of practical importance to understand variations in the survival rate not only for cultivated fish but also for fishery biology studies. With the aim of recognizing critical changes during the first days of life of red porgy larvae, the oxygen consumption, growth, and food utilization were studied. After hatching, the larvae were transferred to two 400 L fiberglass tanks with microalgae (Nannochloropsis oculata) and enriched rotifers (Brachionus plicatilis) as initial food. During the incubation and larval rearing, water temperature was kept at 18.0 ± 0.5°C and salinity ranged from 33.0 to 34.0 psu. Results indicate a decrease in larval growth between day 3 and 4 after hatching, when larvae opened their mouths, began exogenous feeding and have almost exhausted their yolk sac and oil globule. At the end of this period, variations in the carbon and nitrogen content were also detected. Oxygen consumption showed an isometric mass-specific change with an inflexion at day 6 after hatching, which was coincident with the inflation of the gas bladder and the development of gills. The nitrogen coefficient (NQ) revealed a sudden change in the utilization of amino acids and lipids from endogenous reserves between the embryo and the newly hatched larvae. Hatching and first feeding time are two critical changing moments for the larval survival of this species.