Pilot study of an electronic monitoring system on a tropical tuna purse seine vessel in the Atlantic Ocean

The data collected by onboard observers during tropical tuna purse seine fishing operations are commonly used for management purposes. For some types of data, such as discards, observer programs can be the most reliable, and sometimes the only source of information available for management of the fishery. Electronic monitoring (EM) systems are being used in some fisheries as an alternative, or a complement to human observers. The overall objective of this study was to test the use of EM on a tropical tuna purse seiner in the Atlantic Ocean. This objective was split into two main goals: (1) make comparisons between data collected using EM and observers to determine if EM can reliably document fishing (effort, set-type, catch, and bycatch) on the tuna purse seine fishery, and (2) to evaluate the operational aspects of using EM to monitor the tuna purse seine fishery. To achieve these objectives, EM was deployed on the Playa de Bakio, based out of Abidjan, Ivory Coast for three commercial fishing trips between November 28, 2011 and March 27, 2012. During these three trips, 61 sets were monitored using EM systems and by observers. Set-type was correctly identified using EM for 60 of the 61 sets. Tuna catch per set was not significantly different between EM and observer data sets, however, for larger volume sets, EM underestimated tuna catch. Catch composition matched well between EM and observers. However, in sets that were mainly comprised of skipjack, yellowfin tuna were underestimated. Overall, by-catch species were underestimated by EM, but large bodied species such as billfishes were well documented. Based on this research, EM is a viable tool for monitoring effort, set-type, tuna catch, and some types of by-catch within the tropical tuna purse seine fishery. Operational aspects that need to be considered for an EM program to be implemented include defining monitoring objectives, standardising installation and onboard catch handling methodology, and developing data and field service provision frameworks to support the program.