Effect of environmental parameters on acoustic characterisation of pelagic biocenoses in ultra-shallow (5-30 m) coastal areas

The European Marine Strategy Framework Directive (MSFD) requires the achievement of good ecological status of the marine environment (Ministère de l’Écologie, du Développement durable et de l’Énergie, 2013) for all members of European Union. This directive concerns all the component of the marine environment, including fish. Up to now, fish are are monitored mainly in offshore waters through acoustic programs such as PELGAS in Bay of Biscay (Doray et al., 2018) or PELMED (Bourdeix, 2018) in the Mediterranean. However, shallow and ultra-shallow coastal waters (<30m) are not fully covered because large conventional research vessel size and acoustic frequencies (38 Hz) usually used are not suited to insonify these shallow areas. Therefore, there is a lack of information from shallow waters, which is not consistent with MFSD.