Measuring congruence between electronic monitoring and logbook data in Australian Commonwealth longline and gillnet fisheries
Presented also as IOTC-2018-WPDCS14-INF06 (file attached)
Electronic monitoring (EM) has the capacity to collect fisheries-dependent data to support fisheries management decision-making. Following successful pilot studies, EM was introduced into several Australian Commonwealth fisheries in 2015, including the Eastern Tuna and Billfish Fishery (ETBF) and the Gillnet, Hook and Trap (GHAT) sector of the Southern and Eastern Scalefish and Shark Fishery (SESSF). We compared two years of EM analyst and fisher-reported logbook data from the ETBF and GHAT sector to examine the level of congruence in reporting of both retained and discarded catch and protected species interactions. In general, congruence between EM analyst and fisher-reported logbook data in both the ETBF and GHAT sector was higher for retained than for discarded catch, and the ETBF had a higher level of data equivalency than the GHAT sector. Fishery-wide estimates of congruence, however, concealed a large amount of variation among individual and groups of species. EM analyst and fisher-reported logbook data were highly congruent for some species (e.g. tunas, swordfish and gummy shark), but for others there were clear taxonomic (e.g. escolar and rudderfish), identification (e.g. sharks, marlins) and reporting (e.g. draughtboard shark and elephantfish) issues, which reduced overall congruence. There was evidence of increased congruence through time, particularly for discarded bycatch species in the GHAT sector, due presumably to increased manager feedback and communication with fishers on their logbook reporting. While EM analyst and fisher-reported logbook interactions with protected species in the GHAT sector were equivalent, this was not the case for species other than seabirds in the ETBF. In the ETBF, a greater number of interactions were reported by fishers in their logbooks, suggesting a need to modify existing or install additional EM technology to improve on-board vision for the EM analyst. It is important to review the performance of any integrated EM system through time to ensure it is fulfilling the data requirements for the fishery and meeting the overall objectives of the program.