Comparing and contrasting EM derived purse seine fishery data with human observer, onboard sampling and other data sources in support of Project 60

The use of electronic monitoring systems (EMS) is a rapidly expanding area of fisheries monitoring and compliance with the potential to gather unbiased catch and effort data along with information verifying non-target catch, discards and operational characteristics of fisheries. Longline fisheries are well suited to monitoring by EMS where each fishing event can be referenced to a sequentially set hook that is landed and processed in the same general area of the vessel. Monitoring of purse seine effort is more complex due to the larger size of vessels requiring several camera locations and angles to effectively monitor fishing operations and vessel activity. For the same reasons, monitoring the many aspects of a purse seine trip can be difficult to capture by a single human observer and incorporating EMS may significantly improve the overall monitoring coverage. However, before EM data can be considered for incorporation into existing data streams, the quality of EM derived data must be cross checked and verified to assure accurate and comparable information is supplied for science and management purposes. To explore the potential applications of EM onboard a purse seiner, an eight-camera video EMS was installed on a U.S. flagged tuna purse seine vessel conducting a standard commercial fishing trip in the Western Central Pacific Ocean (WCPO). Simultaneous independent data collection was gathered via multiple sources including: 1) by a certified Regional Observer Program (ROP) human observer (HO), 2) by two onboard fisheries biologists/samplers, 3) using the self-reported vessel logsheet data, and 4) utilizing port sampling and cannery unloading weights. Data examined included verification of school and set type, well loading destination and tonnage estimates, set and trip level catch estimates, species composition, length frequency data for the principal tuna species and observations of bycatch handling and disposition/fate.

Preliminary results highlight the information benefits that observers gain by being on the vessel and able to obtain information from many data sources, such as in the determination of set size and species composition. Conversely, EM video footage with precise time and position stamps bring recorded 24/7 has certain advantages over human interpretation. However, the EM analysts converting the video footage to actionable data would benefit from having more frequent and varied pre-trip length calibrations and greater familiarity of WCPO bycatch species. Findings from this study support previous investigations that EMS monitoring of purse seine effort should not be regarded as a replacement of human observers, but as a complimentary tool that can enhance HO programs potentially replacing repetitive tasks, allowing observers to concentrate on other priority duties. HO and EMS should be regarded as complimentary to each other, where their combined monitoring effort produces higher quality fishery data and monitoring information.