The effect of short-term feed-deprivation and moult status on feeding behaviour of the Pacific white shrimp (Litopenaeus vannamei)

There is increasing recognition of the need to understand behaviours of species important in aquaculture to facilitate their production, however to date there has been limited focus in this area. The Pacific white shrimp(Litopenaeus vannamei), for example, is the most cultivated species in crustacean aquaculture globally, yet there are few studies that have addressed its feeding behaviour in detail. The objective of the present study was to evaluate the feeding behaviour of L. vannamei in response to feed-deprivation and moult status. Twenty-four juvenile shrimp (10.51 ± 2.17g) were divided across three different feed-deprivation conditions (+0h (con-trol), +24h or +48h;n=8 per treatment). Shrimp in all treatment groups were provided with their last food intake at 19.00 and subsequently experienced 14h feed-deprivation. Those in the control group were recorded for behaviour at 09.00 the following day and were not feed-deprived for any additional time (+0h), whereas the other treatments were feed-deprived by one (+24h treatment) or two (+48h treatment) extra days. Moult status was constantly monitored as it changed in all shrimp throughout the course of the experiment. Shrimp,provided with food, were observed individually via video in test arenas for 20 min where behaviours (e.g.inactivity, detection, feeding, attraction-to-feed) were recorded. Each shrimp was observed five times across different days with three days between recordings to obtain information on within-individual in addition to between-individual variation. Shrimp feed-deprived for +24h and +48h showed significantly increased feeding activity compared to the control group, which spent more time inactive and performing detection behaviours. Shrimp deprived of food for +48h also had higher attraction-to-feed score, which were positively correlated with feeding activity. Shrimp in the inter-moult stage displayed increased feeding activity and a higher attraction-to-feed score. Longer periods of feed-deprivation reduced within- and between-individual variation across the majority of the behaviours measured. The results of this study highlight the relevance of feed-deprivation and moult status in nutritional trials and provide important baseline information for developing the use of behaviour to improve L.vannamei production.