Comparing electronic monitoring system with observer data for estimating non-target species and discards on French tropical tuna purse seine vessels - ICCAT presentation

Electronic monitoring system (EMS) was recently implemented on French tropical tuna purse seiners to complement observer program both in the Indian and Atlantic Oceans. The main objective was to test the efficiency and the potential of the EMS compared to regular observer programs. ‘Mixed’ trips involving both EMS and on-board observers were conducted on CFTO vessels over 2015-2016 and non-target species and discard data from both observations were compared using generalized linear models. Good matches between methods were obtained for tuna discards. However divergences were noted for non-target catch. For low commercial value species which are systematically discarded, EMS provided similar estimates as on-board observation. However, for sharks, billfishes or high commercial value species, EMS underestimated occurrence and volume compared to regular observers. These species can be handled at different places on board and EMS usually failed to document their retrieval due to camera distance or dead angles. We conclude that with some improvement on camera installation and crew collaboration, EMS can be a promising tool for monitoring discards and non-target catch at an acceptable species identification resolution.