Passive acoustics monitoring (PAM) can contribute to improve feed formulations by providing information on shrimp feeding behavior. The inclusion of attractants , especially those derived from marine animals, have been used to increase chemosensory characteristics and feed intake of soybean-based shrimp diets. However, the evaluation of their effect in shrimp feed intake and behavioral responses is challenging on multiple levels. Th is study used PAM to test the efficiency of attractants included in all-plant diets for Litopenaeus vannamei .
The feeding activity and food consumption (FC) of L. vannamei (7 g) were evaluated using all- plant diets supplemented with krill meal (2%), squid meal (2%) or fish hydrolysate (4% ), as well as a control diet without attractants and a fishmeal diet (12%). Two consecutive trials were performed using “naive” (without previous acclimation to the diets) and “non-naive” shrimp (four days of acclimation) in clear water recirculation system (50-L aquaria). The acoustic feeding activity was monitored by hydrophone s connected to a multitrack recorder (16 bit/192 kHz) , while FC (g) was measured as the amount of food eaten by the shrimp (n=10) in each aquarium over a 30 min period . The clicks produced by shrimp during feeding activity were automatically detect ed and quantified using specific acoustic targets. These data were also used to calculate the relationships between the number of clicks and FC.
An overall improvement was observed in acoustic feeding activity and FC for all-plant diets with attractants in comparison with the control diet, while t he all-plant diet with krill meal showed a significantly similar feeding activity as the fishmeal diet for non-naive shrimp (Figure 1). A strong positive correlation (~r=0.8) was found between FC and number of clicks during 15 and 30 min. The clicking activity analysis through PAM technolog y was proved a reliable tool to help us understand feeding behavior and preferences of shrimp in laboratory experiments.