Passive acoustics monitoring (PAM) can contribute to improve feed formulations by providing information on shrimp feeding behavior or it can be used as a tool to manage feed inputs. Under laboratory conditions, we have utilized PAM to identify
feed modifiers that act as chemoattractants, feeding incitants, and stimulants
in plant-based feed formulations . Bas ed on laboratory results we formulated an “all plant” basal diet (AP) and three AP diets supplemented with 2% krill meal (AP+KM), 2% squid meal (AP+Sq), or 4% fish hydrolysate (AP+FH). These diets were then tested in the laboratory to evaluate the response of the shrimp, in research ponds using automatic feeders equipped with acoustic feed management (AQ1) as well as outdoor tanks where feed inputs were controlled. In the laboratory, the acoustic feeding activity was monitored by hydrophones connected to a multitrack recorder (16 bit/192 kHz), while feed consumption (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 detected 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 basal diet, confirming an improvement in feeding response in the laboratory. To confirm the efficacy in the field, the same feeds were offered to shrimp (30 shrimp/m2) reared in 0.1 ha research ponds each equipped with AQ1 acoustic feeders
which allowed for demand-style feeding. The g rowth and general health of shrimp were monitored via weekly sampling and final production values were determined after fully harvesting each pond.
Harvest was delayed due to a hurricane, which in combination with multiple blue green algae blooms, led to
shrimp mortalities. As a result of low survival, some ponds were excluded from the final data set.
No statistically significant differences were found between the treatments for any major production parameter apart from feed input and feed cost (Table 1) . Significantly more of the AP+FH diet was offered to shrimp in the respective ponds than t hat of the basal diet, suggesting that
fish hydrolysate increases the intensity of the feed response in Pacific white shrimp in semi-intensive pond culture.