Fish Behavior Controlled Feed Delivery System Using Acoustic Techniques

Fish feed is one of the major costs in intensive aquaculture. Feed costs typically range from 30-60% of variable operating costs. Development of an efficient feeding system is needed to maximize growth rates of the fish while eliminating any overfeeding in doing so. Overfeeding has the double negative aspect of increased production costs and increasing the pollutant load from the system. Rapid advances in electronic control technology has led to the introduction of numerous types of automated systems for delivering feed to fish. Some of the recently developed systems rely on the usage of ultrasound, infrared, and visual feed detection that have shown positive results in commercial net pen applications. The proposed research is a focused effort to offer a robust passive acoustic system to monitor fish behavior at the initiation of a feeding event as the feedback mechanism to control feeding dosage. The advantage being immediate feedback to the feed control system so that the feed addition is immediately adjusted to suit the needs of the fish. Aggressive fish movement at the beginning of a feeding event results in air bubbles being produced that emit sounds. An automated hydrophone acoustic system can detect the radiated sound, thus providing a real-time instantaneous feedback monitoring of the fish's feeding behavior. Much as hand feeding relies on the human eye to gauge fish behavior and when to quit hand applying feed pellets to the pond/tank, the bubbles being generated by fish feeding behavior when the fish are aggressively feeding (the desired behavior) will also provide immediate feedback to an automated feed delivery mechanism. Field observations have confirmed the small variation needed to create aggressive feeding behavior and passive feeding behavior (assuming adequate water quality to promote feeding activity in the first place). In addition to the passive acoustic system, an active system that relies on the Doppler shift will be used to monitor the fish aggressive behavior when the sinking pellets are used in net pens.