Review of technological advances for the study of fish behaviour in relation to demersal fishing trawls

In demersal trawling, there is a need to develop more species-selective trawls to minimize discarding in multispecies fisheries. This requires observational tools that can operate at depths and light levels encountered by the commercial fleets. There is a growing tendency towards more fishery-independent stock-assessment methods using survey trawls to provide population indices. This requires the ability to quantify the herding and capture efficiency by species and age groups of such gears. A range of optical and acoustic observation techniques has been developed over the past few decades to assist in these goals. In this paper we update the review of technologies presented at the ICES Symposium on Fish Behaviour in Relation to Fishing Operations held in 1992. Since then, considerable advances in optical, acoustic, and data-processing technology have been made.