In underwater passive acoustic studies, hydrophones are deployed in aquatic environment in order to collect information of the biotope from biotic and abiotic sounds. This methodology has the main advantage to be quite cheap in term of material and personnel. It allows also to gain data from environment that are not reachable for human beings and for long periods of time. Passive acoustic can be used to have different kinds of information such as the type of conveyed messages between organisms, the location of spawning site, the duration of spawning period, etc.
The hypothesis of this project is based on two direct observations.
1) Sounds from nocturnal fish species are more complex than in diurnal species.
2) Different meso- and bathypelagic species possess sound producing apparatus that are well developed.
According to these observation, acoustic communication has to be developed at high depth. This study wants to challenge the deployment of material allowing us the use of sounds and images to study, between 100 and 2500 meter depth, the biology of deep-sea organisms and to better understand the relationships existing at the level of this particular biotope.