Food ingestion and assimilation by the southern brown shrimp Penaeus subtilis under semi-intensive culture in NE Brazil

In recent years in NE Brazil, attempts to increase productivity in extensive marine shrimp farms has focused attention on semi-intensive cultivation methods with native species. The present study was initiated to investigate the diet of Penaeus subtilis under semi-intensive conditions over a complete growth cycle. The experiment was conducted at a commercial shrimp farm on the NE Brazilian coast. The investigation focused on the analysis of stomach contents and stable carbon isotope ratios. Naturally occurring pond biota was the major food source for P. subtilis observed throughout the study. Formulated food constituted 15.61% of the stomach contents (5.99% of stomach volume), accounting for 24.91% of the carbon growth, with the remainder attributed to natural food (average 75.09%). Polychaetes were the most important food type, representing 80.83% of all prey ingested (32.55% of the total food consumed). In the initial growth stages, P. subtilis displayed pronounced detritivorous feeding behaviour. As the shrimp grew, prey organisms were consumed in greater amounts, revealing a more carnivorous habit. Overall, a benthic omnivorous opportunist feeding behaviour was observed.