Preferences and amount of food eaten by the prawn Penaeus esculentus over moult cycle

Abstract

Analysis of the natural diet of prawns over the moult cycle shows a preference for molluscan tissue at all stages, with an apparent greater preference in the stage immediately following the moult dropping in the intermoult stages and then increasing again before the next moult. A laboratory study was carried out to provide more information on feeding behaviour over the moult cycle. Adults of Penaeus esculentus (carapace length 25 to 30 mm, weight 15.5 to 25.2 g) held at 32 to 35 and 23 to 25°C did not feed on the night of ecdysis. On the following nights, feeding increased to peak at 2.7 g of penaeid tissue per day in moult Stage C. For the rest of the moult cycle, feeding was fairly steady at about 1.23 g of penaeid tissue per day but dropped sharply two nights before ecdysis. The prawns increased in weight by 0.7 to 6.1 g (mean 3.5 g) over a moult cycle. A stepwise linear-regression analysis showed that, within the range tested, the increase in weight was not a function of prawn weight, duration of moult cycle (range 14 to 34 days), or daily food consumption (0.95 to 2.33 g). They ate more crustacean tissue (Metapenaeus bennettae) than bivalve tissue (Perna canaliculatus) over the entire moult cycle, except for the night before and after ecdysis, when they ate bivalve tissue almost exclusively.