Feeding activity patterns of the Southern brown shrimp Penaeus subtilis under semi-intensive culture in NE Brazil

This paper investigates the feeding rhythms of Penaeus subtilis under a semi-intensive culture system. The effects of diel variations in water quality and artificial food application on the food intake of the shrimp were also examined. Shrimp were sampled during 24 h periods at 10 day intervals, starting at Day 10 over a 60 day period of the growth cycle. After collection, shrimp had their anterior proventriculus dissected, removed and the contents analysed under a binocular microscope. Water quality was evaluated with an automatic water quality logger, set to automatically conduct 10 min interval readings of temperature, salinity, dissolved oxygen, pH, and ammonia for a continuous 24 h cycle. A total of 869 shrimp had their stomach contents analysed, 3369 individual measurements of water quality (including Secchi disk visibility and pond depth) were conducted. Artificial feeding promoted an enhanced consumption of natural food. Recurrent bouts of food intake occurred soon after the spread of pellets in the early morning and late afternoon. Observed shrimp feeding rhythms were irregular and occurred during both day and night. No significant differences were found between diurnal and nocturnal food consumption levels. Water quality (i.e. temperature, pH, salinity and dissolved oxygen) significantly affected food intake ( P < 0.05), although a low correlation ( R 2 = 0.267) was found. These findings indicate that further research is needed to examine the factors involved in penaeid shrimp feeding behaviour and feeding periodicity under semi-intensive pond systems in order to develop more efficient feed management practices.